# Caesar cipher

Implement a Caesar cipher, both encoding and decoding.
The key is an integer from 1 to 25.

Caesar cipher
You are encouraged to solve this task according to the task description, using any language you may know.

This cipher rotates (either towards left or right) the letters of the alphabet (A to Z).

The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A).
So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC".

This simple "mono-alphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys.

Caesar cipher is identical to Vigenère cipher with a key of length 1.
Also, Rot-13 is identical to Caesar cipher with key 13.

## 8th

```\ Ensure the output char is in the correct range:
: modulate \ char base -- char
tuck n:- 26 n:+ 26 n:mod n:+ ;

\ Symmetric Caesar cipher.  Input is text and number of characters to advance
\ (or retreat, if negative).  That value should be in the range 1..26
: caesar \ intext key -- outext
>r
(
\ Ignore anything below '.' as punctuation:
dup '. n:> if
\ Do the conversion
dup r@ n:+ swap
\ Wrap appropriately
'A 'Z between if 'A else 'a then modulate
then
) s:map rdrop ;

"The five boxing wizards jump quickly!"
dup . cr
1  caesar dup . cr
-1 caesar . cr
bye
```
Output:
```The five boxing wizards jump quickly!
Uif gjwf cpyjoh xjabset kvnq rvjdlmz!
The five boxing wizards jump quickly!
```

## 11l

```F caesar(string, =key, decode = 0B)
I decode
key = 26 - key

V r = ‘ ’ * string.len
L(c) string
r[L.index] = S c
‘a’..‘z’
Char(code' (c.code - ‘a’.code + key) % 26 + ‘a’.code)
‘A’..‘Z’
Char(code' (c.code - ‘A’.code + key) % 26 + ‘A’.code)
E
c
R r

V msg = ‘The quick brown fox jumped over the lazy dogs’
print(msg)
V enc = caesar(msg, 11)
print(enc)
print(caesar(enc, 11, decode' 1B))```
Output:
```The quick brown fox jumped over the lazy dogs
Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozrd
The quick brown fox jumped over the lazy dogs
```

## 360 Assembly

A good example of the use of TR instruction to translate a character.

```*        Caesar cypher             04/01/2019
CAESARO  PROLOG
XPRNT  PHRASE,L'PHRASE    print phrase
LH     R3,OFFSET          offset
BAL    R14,CYPHER         call cypher
LNR    R3,R3              -offset
BAL    R14,CYPHER         call cypher
EPILOG
CYPHER   LA     R4,REF(R3)         @ref+offset
MVC    A,0(R4)            for A to I
MVC    J,9(R4)            for J to R
MVC    S,18(R4)           for S to Z
TR     PHRASE,TABLE       translate
XPRNT  PHRASE,L'PHRASE    print phrase
BR     R14                return
OFFSET   DC     H'22'              between -25 and +25
PHRASE   DC     CL37'THE FIVE BOXING WIZARDS JUMP QUICKLY'
DC     CL26'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
REF      DC     CL26'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
DC     CL26'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
TABLE    DC     CL256' '           translate table for TR
ORG    TABLE+C'A'
A        DS     CL9
ORG    TABLE+C'J'
J        DS     CL9
ORG    TABLE+C'S'
S        DS     CL8
ORG
YREGS
END    CAESARO```
Output:
```THE FIVE BOXING WIZARDS JUMP QUICKLY
PDA BERA XKTEJC SEVWNZO FQIL MQEYGHU
THE FIVE BOXING WIZARDS JUMP QUICKLY
```

## AArch64 Assembly

Works with: as version Raspberry Pi 3B version Buster 64 bits
or android 64 bits with application Termux
```/* ARM assembly AARCH64 Raspberry PI 3B */
/*  program caresarcode64.s   */
/************************************/
/* Constantes                       */
/************************************/
/* for this file see task include a file in language AArch64 assembly*/
.include "../includeConstantesARM64.inc"
.equ KEY,                 23
.equ STRINGSIZE,          500
/************************************/
/* Initialized data                 */
/************************************/
.data
szMessString:            .asciz "String :\n"
szMessEncrip:            .asciz "\nEncrypted :\n"
szMessDecrip:            .asciz "\nDecrypted :\n"
szString1:               .asciz "The quick brown fox jumps over the lazy dog."

szCarriageReturn:        .asciz "\n"
/************************************/
/* UnInitialized data               */
/************************************/
.bss
szString2:                .skip  STRINGSIZE
szString3:                .skip  STRINGSIZE
/************************************/
/*  code section                    */
/************************************/
.text
.global main
main:
bl affichageMess
bl affichageMess
mov x2,#KEY                                 // key
bl encrypt
bl affichageMess
bl affichageMess
mov x2,#KEY                                 // key
bl decrypt
bl affichageMess
bl affichageMess
bl affichageMess
100:                                            // standard end of the program
mov x0, #0                                  // return code
mov x8,EXIT
svc 0                                       // perform system call
/******************************************************************/
/*     encrypt strings                         */
/******************************************************************/
/* x0 contains the address of the string1 */
/* x1 contains the address of the encrypted string */
/* x2 contains the key (1-25)                     */
encrypt:
stp x3,lr,[sp,-16]!       // save  registers
stp x4,x5,[sp,-16]!       // save  registers
mov x3,#0                 // counter byte string 1
1:
ldrb w4,[x0,x3]           // load byte string 1
cmp w4,#0                 // zero final ?
bne 2f
strb w4,[x1,x3]
mov x0,x3
b 100f
2:
cmp w4,#65                // < A ?
bge 3f
strb w4,[x1,x3]
b 1b                      // and loop
3:
cmp x4,#90                // > Z
bgt 4f
cmp x4,#90                // > Z
sub x5,x4,26
csel x4,x5,x4,gt
//subgt x4,#26
strb w4,[x1,x3]
b 1b
4:
cmp x4,#97                // < a ?
bge 5f
strb w4,[x1,x3]
b 1b
5:
cmp x4,#122               //> z
ble 6f
strb w4,[x1,x3]
b 1b
6:
cmp x4,#122
sub x5,x4,26
csel x4,x5,x4,gt
//subgt x4,#26
strb w4,[x1,x3]
b 1b

100:
ldp x4,x5,[sp],16        // restaur  registers
ldp x3,lr,[sp],16            // restaur  registers
ret
/******************************************************************/
/*     decrypt strings                                           */
/******************************************************************/
/* x0 contains the address of the encrypted string1 */
/* x1 contains the address of the decrypted string */
/* x2 contains the key (1-25)                     */
decrypt:
stp x3,lr,[sp,-16]!      // save  registers
stp x4,x5,[sp,-16]!      // save  registers
mov x3,#0                // counter byte string 1
1:
ldrb w4,[x0,x3]          // load byte string 1
cmp x4,#0                // zero final ?
bne 2f
strb w4,[x1,x3]
mov x0,x3
b 100f
2:
cmp x4,#65               // < A ?
bge 3f
strb w4,[x1,x3]
b 1b                     // and loop
3:
cmp x4,#90               // > Z
bgt 4f
sub x4,x4,x2             // substract key
cmp x4,#65               // < A
csel x4,x5,x4,lt
strb w4,[x1,x3]
b 1b
4:
cmp x4,#97               // < a ?
bge 5f
strb w4,[x1,x3]
b 1b
5:
cmp x4,#122              // > z
ble 6f
strb w4,[x1,x3]
b 1b
6:
sub x4,x4,x2                // substract key
cmp x4,#97               // < a
csel x4,x5,x4,lt
strb w4,[x1,x3]
b 1b

100:
ldp x4,x5,[sp],16        // restaur  registers
ldp x3,lr,[sp],16        // restaur  registers
ret
/***************************************************/
/*      ROUTINES INCLUDE                           */
/***************************************************/
.include "../includeARM64.inc"```
Output:
```String :
The quick brown fox jumps over the lazy dog.
Encrypted :
Qeb nrfzh yoltk clu grjmp lsbo qeb ixwv ald.
Decrypted :
The quick brown fox jumps over the lazy dog.
```

## Action!

```CHAR FUNC Shift(CHAR c BYTE code)
CHAR base

IF c>='a AND c<='z THEN
base='a
ELSEIF c>='A AND c<='Z THEN
base='A
ELSE
RETURN (c)
FI
c==+code-base
c==MOD 26
RETURN (c+base)

PROC Encrypt(CHAR ARRAY in,out BYTE code)
INT i

out(0)=in(0)
FOR i=1 TO in(0)
DO
out(i)=Shift(in(i),code)
OD
RETURN

PROC Decrypt(CHAR ARRAY in,out BYTE code)
Encrypt(in,out,26-code)
RETURN

PROC Test(CHAR ARRAY in BYTE code)
CHAR ARRAY enc(256),dec(256)

PrintE("Original:") PrintE(in)
Encrypt(in,enc,code)
PrintF("Encrypted code=%B:%E",code) PrintE(enc)
Decrypt(enc,dec,code)
PrintF("Decrypted code=%B:%E",code) PrintE(dec)
PutE()
RETURN

PROC Main()
Test("The quick brown fox jumps over the lazy dog.",23)
Test("The quick brown fox jumps over the lazy dog.",5)
RETURN```
Output:
```Original:
The quick brown fox jumps over the lazy dog.
Encrypted code=23:
Qeb nrfzh yoltk clu grjmp lsbo qeb ixwv ald.
Decrypted code=23:
The quick brown fox jumps over the lazy dog.

Original:
The quick brown fox jumps over the lazy dog.
Encrypted code=5:
Ymj vznhp gwtbs ktc ozrux tajw ymj qfed itl.
Decrypted code=5:
The quick brown fox jumps over the lazy dog.
```

```-- Caesar Cipher Implementation in Ada

procedure Caesar is

-- Base function to encrypt a character
function Cipher(Char_To_Encrypt: Character; Shift: Integer; Base: Character) return Character is
Base_Pos : constant Natural := Character'Pos(Base);
begin
return Character'Val((Character'Pos(Char_To_Encrypt) + Shift - Base_Pos) mod 26 + Base_Pos);
end Cipher;

-- Function to encrypt a character
function Encrypt_Char(Char_To_Encrypt: Character; Shift: Integer) return Character is
begin
case Char_To_Encrypt is
when 'A'..'Z' =>
-- Encrypt uppercase letters
return Cipher (Char_To_Encrypt, Shift, 'A');
when 'a'..'z' =>
-- Encrypt lowercase letters
return Cipher (Char_To_Encrypt, Shift, 'a');
when others =>
-- Leave other characters unchanged
return Char_To_Encrypt;
end case;
end Encrypt_Char;

-- Function to decrypt a character
function Decrypt_Char(Char_To_Decrypt: Character; Shift: Integer) return Character is
begin
return Encrypt_Char(Char_To_Decrypt, -Shift);
end Decrypt_Char;

Shift: Positive := 3; -- Default key from "Commentarii de Bello Gallico" shift cipher
-- Shift value (can be any positive integer)

Encrypted_Message: String(Message'Range);
Decrypted_Message: String(Message'Range);
begin
-- Encrypt the message
for I in Message'Range loop
Encrypted_Message(I) := Encrypt_Char(Message(I), Shift);
end loop;

-- Decrypt the encrypted message
for I in Message'Range loop
Decrypted_Message(I) := Decrypt_Char(Encrypted_Message(I), Shift);
end loop;

-- Display results
Put_Line("Plaintext: " & Message);
Put_Line("Ciphertext: " & Encrypted_Message);
Put_Line("Decrypted Ciphertext: " & Decrypted_Message);

end Caesar;
```
Output:
```> ./caesar
The five boxing wizards jump quickly
Plaintext: The five boxing wizards jump quickly
Ciphertext: Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted Ciphertext: The five boxing wizards jump quickly
```

## ALGOL 68

Translation of: Ada – Note: This specimen retains the original Ada coding style.
Works with: ALGOL 68 version Revision 1 - no extensions to language used.
Works with: ALGOL 68G version Any - tested with release 1.18.0-9h.tiny.
```#!/usr/local/bin/a68g --script #

program caesar: BEGIN

MODE MODXXVI = SHORT SHORT INT; # MOD26 #

PROC to m26 = (CHAR c, offset)MODXXVI:
BEGIN
ABS c - ABS offset
END #to m26#;

PROC to char = (MODXXVI value, CHAR offset)CHAR:
BEGIN
REPR ( ABS offset + value MOD 26 )
END #to char#;

PROC encrypt = (STRING plain, MODXXVI key)STRING:
BEGIN
[UPB plain]CHAR ciph;
FOR i TO UPB plain DO
CHAR c = plain[i];
ciph[i]:=
IF "A" <= c AND c <= "Z" THEN
to char(to m26(c, "A")+key, "A")
ELIF "a" <= c AND c <= "z" THEN
to char(to m26(c, "a")+key, "a")
ELSE
c
FI
OD;
ciph
END #encrypt#;

# caesar main program #
STRING text := "The five boxing wizards jump quickly" # OR read string #;
MODXXVI key := 3; # Default key from "Bello Gallico" #

printf((\$gl\$, "Plaintext ------------>" + text));
text := encrypt(text, key);
printf((\$gl\$, "Ciphertext ----------->" + text));
printf((\$gl\$, "Decrypted Ciphertext ->" + encrypt(text, -key)))

END #caesar#```
Output:
```Plaintext ------------>The five boxing wizards jump quickly
Ciphertext ----------->Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted Ciphertext ->The five boxing wizards jump quickly
```

## APL

```      ∇CAESAR[⎕]∇
∇
[0]   A←K CAESAR V
[2]   ((,V∊A)/,V)←A[⎕IO+52|(2×K)+((A⍳,V)-⎕IO)~52]
[3]   A←V
∇
```
Output:
```      6 CAESAR ⎕←TEXT_MATRIX
This method uses selective specification
(similar to pattern matching in Haskell)
to modify only alphabetic characters.

Znoy skznuj ayky ykrkizobk yvkioloigzout
(yosorgx zu vgzzkxt sgzinotm ot Ngyqkrr)
zu sujole utre grvnghkzoi ingxgizkxy.

¯1 CAESAR ⎕←ENCRYPTED
Ofhbujwf lfzt (efdszqujoh) xpslt: IBM 9000
Negative keys (decrypting) works: HAL 9000

¯1.5 CAESAR ⎕←CAPSLOCK
fUN FACT: FRACTIONAL KEYS SWITCH FROM upper case TO LOWER CASE.
Esl dyar: dpyargmlyj icwq qugraf dpmk TOODQ BZRD rm jmucp ayqc.
```

## AppleScript

```(* Only non-accented English letters are altered here. *)

on caesarDecipher(txt, |key|)
return caesarEncipher(txt, -|key|)
end caesarDecipher

on caesarEncipher(txt, |key|)
set codePoints to id of txt
set keyPlus25 to |key| mod 26 + 25
repeat with thisCode in codePoints
tell thisCode mod 32
if ((it < 27) and (it > 0) and (thisCode div 64 is 1)) then ¬
set thisCode's contents to thisCode - it + (it + keyPlus25) mod 26 + 1
end tell
end repeat

return string id codePoints
end caesarEncipher

-- Test code:
set txt to "ROMANES EUNT DOMUS!
The quick brown fox jumps over the lazy dog."
set |key| to 9

set enciphered to caesarEncipher(txt, |key|)
set deciphered to caesarDecipher(enciphered, |key|)
return "Text: '" & txt & ("'" & linefeed & "Key: " & |key| & linefeed & linefeed) & (enciphered & linefeed & deciphered)
```
Output:
```"Text: 'ROMANES EUNT DOMUS!
The quick brown fox jumps over the lazy dog.'
Key: 9

AXVJWNB NDWC MXVDB!
Cqn zdrlt kaxfw oxg sdvyb xena cqn ujih mxp.
ROMANES EUNT DOMUS!
The quick brown fox jumps over the lazy dog."
```

## Applesoft BASIC

```100 INPUT ""; T\$

110 LET K% = RND(1) * 25 + 1
120 PRINT "ENCODED WITH ";
130 GOSUB 200ENCODED

140 LET K% = 26 - K%
150 PRINT "DECODED WITH ";
160 GOSUB 200DECODED

170 END

REM ENCODED/DECODED
200 PRINT "CAESAR " K%;
210 LET K\$(1) = " (ROT-13)"
220 PRINT K\$(K% = 13)
230 GOSUB 300CAESAR
240 PRINT T\$
250 RETURN

REM CAESAR T\$ K%
300 FOR I = 1 TO LEN(T\$)
310    LET C\$ = MID\$(T\$, I, 1)
320    GOSUB 400ENCODE
330    LET L = I - 1
340    LET T\$(0) = MID\$(T\$, 1, L)
350    LET L = I + 1
360    LET T\$ = C\$ + MID\$(T\$, L)
370    LET T\$ = T\$(0) + T\$
380 NEXT I
390 RETURN

REM ENCODE C\$ K%
400 LET C = ASC(C\$)
410 LET L = (C > 95) * 32
420 LET C = C - L
430 IF C < 65 THEN RETURN
440 IF C > 90 THEN RETURN
450 LET C = C + K%
460 IF C > 90 THEN C = C - 26
470 LET C\$ = CHR\$(C + L)
480 RETURN```
Output:
```]RUN
The quick brown fox jumps over the lazy dog.
ENCODED WITH CAESAR 12
Ftq cguow ndaiz raj vgybe ahqd ftq xmlk pas.
DECODED WITH CAESAR 14
The quick brown fox jumps over the lazy dog.

]?RND(-6):RUN
4.48226274E-08
PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS
ENCODED WITH CAESAR 13 (ROT-13)
CNPX ZL OBK JVGU SVIR QBMRA YVDHBE WHTF
DECODED WITH CAESAR 13 (ROT-13)
PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS

]K%=1:GOTO120
ENCODED WITH CAESAR 1
QBDL NZ CPY XJUI GJWF EPAFO MJRVPS KVHT
DECODED WITH CAESAR 25
PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS```

## Arc

```(= rot (fn (L N)
(if
(and (<= 65 L) (>= 90 L))
(do
(= L (- L 65))
(= L (mod (+ N L) 26))
(= L (+ L 65)))
(and (<= 97 L) (>= 122 L))
(do
(= L (- L 97))
(= L (mod (+ N L) 26))
(= L (+ L 97))))
L))

(= caesar (fn (text (o shift))
(unless shift (= shift 13))
(= output (map [int _] (coerce text 'cons)))
(= output (map [rot _ shift] output))
(string output)
))```
Output:
```(caesar "The quick brown fox jumps over the lazy dog.")
"Gur dhvpx oebja sbk whzcf bire gur ynml qbt."```

## ARM Assembly

Works with: as version Raspberry Pi
```/* ARM assembly Raspberry PI  */
/*  program caresarcode.s   */

/* Constantes    */
.equ STDOUT, 1                           @ Linux output console
.equ EXIT,   1                           @ Linux syscall
.equ WRITE,  4                           @ Linux syscall

.equ STRINGSIZE,          500

/* Initialized data */
.data
szMessString:            .asciz "String :\n"
szMessEncrip:            .asciz "\nEncrypted :\n"
szMessDecrip:            .asciz "\nDecrypted :\n"
szString1:               .asciz "Why study medicine because there is internet ?"

szCarriageReturn:       .asciz "\n"

/* UnInitialized data */
.bss
szString2:                .skip  STRINGSIZE
szString3:                .skip  STRINGSIZE
/*  code section */
.text
.global main
main:

bl affichageMess
bl affichageMess
mov r2,#20                                  @ key
bl encrypt
bl affichageMess
bl affichageMess
mov r2,#20                                  @ key
bl decrypt
bl affichageMess
bl affichageMess
bl affichageMess
100:                                            @ standard end of the program
mov r0, #0                                  @ return code
mov r7, #EXIT                               @ request to exit program
svc 0                                       @ perform system call
/******************************************************************/
/*     encrypt strings                         */
/******************************************************************/
/* r0 contains the address of the string1 */
/* r1 contains the address of the encrypted string */
/* r2 contains the key (1-25)                     */
encrypt:
push {r3,r4,lr}           @ save  registers
mov r3,#0                 @ counter byte string 1
1:
ldrb r4,[r0,r3]           @ load byte string 1
cmp r4,#0                 @ zero final ?
streqb r4,[r1,r3]
moveq r0,r3
beq 100f
cmp r4,#65                @ < A ?
strltb r4,[r1,r3]
blt 1b
cmp r4,#90                @ > Z
bgt 2f
cmp r4,#90                @ > Z
subgt r4,#26
strb r4,[r1,r3]
b 1b
2:
cmp r4,#97                @ < a ?
strltb r4,[r1,r3]
blt 1b
cmp r4,#122               @> z
strgtb r4,[r1,r3]
bgt 1b
cmp r4,#122
subgt r4,#26
strb r4,[r1,r3]
b 1b

100:
pop {r3,r4,lr}            @ restaur registers
bx lr                     @ return
/******************************************************************/
/*     decrypt strings                                           */
/******************************************************************/
/* r0 contains the address of the encrypted string1 */
/* r1 contains the address of the decrypted string */
/* r2 contains the key (1-25)                     */
decrypt:
push {r3,r4,lr}          @ save  registers
mov r3,#0                @ counter byte string 1
1:
ldrb r4,[r0,r3]          @ load byte string 1
cmp r4,#0                @ zero final ?
streqb r4,[r1,r3]
moveq r0,r3
beq 100f
cmp r4,#65               @ < A ?
strltb r4,[r1,r3]
blt 1b
cmp r4,#90               @ > Z
bgt 2f
sub r4,r2                @ substract key
cmp r4,#65               @ < A
strb r4,[r1,r3]
b 1b
2:
cmp r4,#97               @ < a ?
strltb r4,[r1,r3]
blt 1b
cmp r4,#122              @ > z
strgtb r4,[r1,r3]
bgt 1b
sub r4,r2                @ substract key
cmp r4,#97               @ < a
strb r4,[r1,r3]
b 1b

100:
pop {r3,r4,lr}           @ restaur registers
bx lr                    @ return
/******************************************************************/
/*     display text with size calculation                         */
/******************************************************************/
/* r0 contains the address of the message */
affichageMess:
push {r0,r1,r2,r7,lr}                       @ save  registers
mov r2,#0                                   @ counter length */
1:                                              @ loop length calculation
ldrb r1,[r0,r2]                             @ read octet start position + index
cmp r1,#0                                   @ if 0 its over
bne 1b                                      @ and loop
@ so here r2 contains the length of the message
mov r1,r0                                   @ address message in r1
mov r0,#STDOUT                              @ code to write to the standard output Linux
mov r7, #WRITE                              @ code call system "write"
svc #0                                      @ call system
pop {r0,r1,r2,r7,lr}                        @ restaur registers
bx lr                                       @ return```

## Arturo

Translation of: 11l
```ia: to :integer `a`
iA: to :integer `A`
lowAZ: `a`..`z`
uppAZ: `A`..`Z`

caesar: function [s, xx][
k: (not? null? attr 'decode)? -> 26-xx -> xx
result: new ""
loop s 'i [
(in? i lowAZ)? -> 'result ++ to :char ia + (k + (to :integer i) - ia) % 26
[
(in? i uppAZ)? -> 'result ++ to :char iA + (k + (to :integer i) - iA) % 26
-> 'result ++ i
]
]
return result
]

msg: "The quick brown fox jumped over the lazy dogs"
print ["Original :" msg]
enc: caesar msg 11
print [" Encoded :" enc]
print [" Decoded :" caesar.decode enc 11]
```
Output:
```Original : The quick brown fox jumped over the lazy dogs
Encoded : Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozrd
Decoded : The quick brown fox jumped over the lazy dogs```

## Astro

```fun caesar(s, k, decode: false):
if decode:
k = 26 - k
result = ''
for i in s.uppercase() where 65 <= ord(i) <= 90:
result.push! char(ord(i) - 65 + k) mod 26 + 65
return result

let message = "The quick brown fox jumped over the lazy dogs"
let encrypted = caesar(msg, 11)
let decrypted = caesar(enc, 11, decode: true)

print(message, encrypted, decrypted, sep: '\n')
```

## AutoHotkey

This ungodly solution is an attempt at code-golf. It requires input to be all-caps alphabetic, only works on AutoHotkey_L Unicode, and might not run on x64

```n=2
s=HI
t:=&s
While *t
o.=Chr(Mod(*t-65+n,26)+65),t+=2
MsgBox % o
```

This next one is much more sane and handles input very well, including case.

```Caesar(string, n){
Loop Parse, string
{
If (Asc(A_LoopField) >= Asc("A") and Asc(A_LoopField) <= Asc("Z"))
out .= Chr(Mod(Asc(A_LoopField)-Asc("A")+n,26)+Asc("A"))
Else If (Asc(A_LoopField) >= Asc("a") and Asc(A_LoopField) <= Asc("z"))
out .= Chr(Mod(Asc(A_LoopField)-Asc("a")+n,26)+Asc("a"))
Else out .= A_LoopField
}
return out
}

MsgBox % Caesar("h i", 2) "`n" Caesar("Hi", 20)
```
Output:
```j k
Bc```

## AutoIt

The Ceasar Funktion can enrcypt and decrypt, standart is Encryption, to Decrypt set third parameter to False

```\$Caesar = Caesar("Hi", 2, True)
MsgBox(0, "Caesar", \$Caesar)
Func Caesar(\$String, \$int, \$encrypt = True)
If Not IsNumber(\$int) Or Not StringIsDigit(\$int) Then Return SetError(1, 0, 0)
If \$int < 1 Or \$int > 25 Then Return SetError(2, 0, 0)
Local \$sLetters, \$x
\$String = StringUpper(\$String)
\$split = StringSplit(\$String, "")
For \$i = 1 To \$split[0]
If Asc(\$split[\$i]) - 64 > 26 Or Asc(\$split[\$i]) - 64 < 1 Then
\$sLetters &= \$split[\$i]
ContinueLoop
EndIf
If \$encrypt = True Then
\$move = Asc(\$split[\$i]) - 64 + \$int
Else
\$move = Asc(\$split[\$i]) - 64 - \$int
EndIf
If \$move > 26 Then
\$move -= 26
ElseIf \$move < 1 Then
\$move += 26
EndIf
While \$move
\$x = Mod(\$move, 26)
If \$x = 0 Then \$x = 26
\$sLetters &= Chr(\$x + 64)
\$move = (\$move - \$x) / 26
WEnd
Next
Return \$sLetters
EndFunc   ;==>Caesar
```

## AWK

```#!/usr/bin/awk -f

BEGIN {
message = "My hovercraft is full of eels."
key = 1

cypher = caesarEncode(key, message)
clear  = caesarDecode(key, cypher)

print "message: " message
print " cypher: " cypher
print "  clear: " clear
exit
}

function caesarEncode(key, message) {
return caesarXlat(key, message, "encode")
}

function caesarDecode(key, message) {
return caesarXlat(key, message, "decode")
}

function caesarXlat(key, message, dir,    plain, cypher, i, num, s) {
plain = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
cypher = substr(plain, key+1) substr(plain, 1, key)

if (toupper(substr(dir, 1, 1)) == "D") {
s = plain
plain = cypher
cypher = s
}

s = ""
message = toupper(message)
for (i = 1; i <= length(message); i++) {
num = index(plain, substr(message, i, 1))
if (num) s = s substr(cypher, num, 1)
else s = s substr(message, i, 1)
}
return s
}
```
Output:
```message: My hovercraft is full of eels.
cypher: NZ IPWFSDSBGU JT GVMM PG FFMT.
clear: MY HOVERCRAFT IS FULL OF EELS.
```

## Babel

```((main
{"The quick brown fox jumps over the lazy dog.\n"
dup <<

17 caesar_enc !
dup <<

17 caesar_dec !
<<})

(caesar_enc
{ 2 take
{ caesar_enc_loop ! }
nest })

(caesar_enc_loop {
give
<- str2ar
{({ dup is_upper ! }
{ 0x40 -
-> dup <-
encrypt !
0x40 + }
{ dup is_lower ! }
{ 0x60 -
-> dup <-
encrypt !
0x60 + }
{ 1 }
{fnord})
cond}
eachar
collect !
ls2lf ar2str})

(collect { -1 take })

(encrypt { + 1 - 26 % 1 + })

(caesar_dec { <- 26 -> - caesar_enc ! })

(is_upper
{ dup
<- 0x40 cugt ->
0x5b cult
cand })

(is_lower
{ dup
<- 0x60 cugt ->
0x7b cult
cand }))```
Output:
```The quick brown fox jumps over the lazy dog.
Kyv hlztb sifne wfo aldgj fmvi kyv crqp ufx.
The quick brown fox jumps over the lazy dog.```

## BaCon

```CONST lc\$ = "abcdefghijklmnopqrstuvwxyz"
CONST uc\$ = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

CONST txt\$ = "The quick brown fox jumps over the lazy dog."

FUNCTION Ceasar\$(t\$, k)

lk\$ = MID\$(lc\$ & lc\$, k+1, 26)
uk\$ = MID\$(uc\$ & uc\$, k+1, 26)

RETURN REPLACE\$(t\$, lc\$ & uc\$, lk\$ & uk\$, 2)

END FUNCTION

tokey = RANDOM(25)+1
PRINT "Encrypting text with key: ", tokey

en\$ = Ceasar\$(txt\$, tokey)

PRINT "Encrypted: ", en\$
PRINT "Decrypted: ", Ceasar\$(en\$, 26-tokey)
```
Output:
```user@host \$ bacon ceasar
Converting 'ceasar.bac'... done, 20 lines were processed in 0.015 seconds.
Compiling 'ceasar.bac'... cc  -c ceasar.bac.c
cc -o ceasar ceasar.bac.o -lbacon -lm
user@host \$ ./ceasar
Encrypting text with key: 23
Encrypted: Qeb nrfzh yoltk clu grjmp lsbo qeb ixwv ald.
Decrypted: The quick brown fox jumps over the lazy dog.
```

## bash

Caesar cipher bash implementation

```caesar_cipher() {

# michaeltd 2019-11-30
# https://en.wikipedia.org/wiki/Caesar_cipher
# E n ( x ) = ( x + n ) mod 26.
# D n ( x ) = ( x − n ) mod 26.

local -a _ABC=( "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R" "S" "T" "U" "V" "W" "X" "Y" "Z" )
local -a _abc=( "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z" )

local _out

if (( \$# < 3 )) || [[ "\$1" != "-e" && "\$1" != "-d" ]] || (( \$2 < 1 || \$2 > 25 )); then
echo "Usage: \${FUNCNAME[0]} -e|-d rotation (1-25) argument[(s)...]" >&2
return 1
fi

_func="\${1}"; shift
_rotval="\${1}"; shift

while [[ -n "\${1}" ]]; do
for (( i = 0; i < \${#1}; i++ )); do
for (( x = 0; x < \${#_abc[*]}; x++ )); do
case "\${_func}" in
"-e")
[[ "\${1:\$i:1}" == "\${_ABC[\$x]}" ]] && _out+="\${_ABC[(( ( x + _rotval ) % 26 ))]}" && break
[[ "\${1:\$i:1}" == "\${_abc[\$x]}" ]] && _out+="\${_abc[(( ( x + _rotval ) % 26 ))]}" && break;;
"-d")
[[ "\${1:\$i:1}" == "\${_ABC[\$x]}" ]] && _out+="\${_ABC[(( ( x - _rotval ) % 26 ))]}" && break
[[ "\${1:\$i:1}" == "\${_abc[\$x]}" ]] && _out+="\${_abc[(( ( x - _rotval ) % 26 ))]}" && break;;
esac
# If char has not been found by now lets add it as is.
(( x == \${#_abc[*]} - 1 )) && _out+="\${1:\$i:1}"
done
done
_out+=" "
shift
done
echo "\${_out[*]}"
}
```
Input:
```caesar_cipher -e 13 "Hello World!"
```
Output:
```Uryyb Jbeyq!
```
Input:
```caesar_cipher -d 13 "Uryyb Jbeyq!"
```
Output:
```Hello World!
```

## BASIC

### BASIC256

```# Caeser Cipher
# basic256 1.1.4.0

dec\$ = ""
type\$ = "cleartext "

input "If decrypting enter " + "<d> " + " -- else press enter > ",dec\$  # it's a klooj I know...
input "Enter offset > ", iOffset

if dec\$ = "d" then
iOffset = 26 - iOffset
type\$ = "ciphertext "
end if

input "Enter " + type\$ + "> ", str\$

str\$ = upper(str\$)          # a bit of a cheat really, however old school encryption is always upper case
len = length(str\$)

for i = 1 to len
iTemp =  asc(mid(str\$,i,1))

if iTemp > 64 AND iTemp < 91 then
iTemp = ((iTemp - 65) + iOffset) % 26
print chr(iTemp + 65);
else
print chr(iTemp);
end if

next i
```
Output:
```Enter offset > 21
Enter cleartext > My hovercraft is full of eels.
HT CJQZMXMVAO DN APGG JA ZZGN.

Enter offset > 21
Enter ciphertext > HT CJQZMXMVAO DN APGG JA ZZGN.
MY HOVERCRAFT IS FULL OF EELS.
```

### BBC BASIC

```      plaintext\$ = "Pack my box with five dozen liquor jugs"
PRINT plaintext\$

key% = RND(25)
cyphertext\$ = FNcaesar(plaintext\$, key%)
PRINT cyphertext\$

decyphered\$ = FNcaesar(cyphertext\$, 26-key%)
PRINT decyphered\$

END

DEF FNcaesar(text\$, key%)
LOCAL I%, C%
FOR I% = 1 TO LEN(text\$)
C% = ASC(MID\$(text\$,I%))
IF (C% AND &1F) >= 1 AND (C% AND &1F) <= 26 THEN
C% = (C% AND &E0) OR (((C% AND &1F) + key% - 1) MOD 26 + 1)
MID\$(text\$, I%, 1) = CHR\$(C%)
ENDIF
NEXT
= text\$
```
Output:
```Pack my box with five dozen liquor jugs
Zkmu wi lyh gsdr psfo nyjox vsaeyb teqc
Pack my box with five dozen liquor jugs```

### Chipmunk Basic

Works with: Chipmunk Basic version 3.6.4
Works with: QBasic
Translation of: BASIC256
```10 rem Caesar cipher
20 cls
30 dec\$ = ""
40 type\$ = "cleartext "
50 print "If decrypting enter  "+"<d> "+" -- else press enter "; : input dec\$
60 input "Enter offset > ",ioffset
70 if dec\$ = "d" then
80   ioffset = 26-ioffset
90   type\$ = "ciphertext "
100 endif
110 print "Enter "+type\$+"> ";
150 for i = 1 to longitud
170   if itemp > 64 and itemp < 91 then
180     itemp = ((itemp-65)+ioffset) mod 26
190     print chr\$(itemp+65);
200   else
210     print chr\$(itemp);
220   endif
230 next i
240 print
250 end
```
Output:
``` >run
If decrypting enter  <d>  -- else press enter ?
Enter offset > 21
Enter cleartext > ? My hovercraft is full of eels.
HT CJQZMXMVAO DN APGG JA ZZGN.
>run
If decrypting enter  <d>  -- else press enter ? d
Enter offset > 21
Enter ciphertext > ? HT CJQZMXMVAO DN APGG JA ZZGN.
MY HOVERCRAFT IS FULL OF EELS.```

### GW-BASIC

Works with: Chipmunk Basic
Works with: PC-BASIC version any
Works with: QBasic
Works with: MSX BASIC
Translation of: Chipmunk Basic
```10 REM Caesar cipher
20 CLS
30 DEC\$ = ""
40 TYPE\$ = "cleartext "
50 PRINT "If decrypting enter  "+"<d> "+" -- else press enter "; : INPUT DEC\$
60 INPUT "Enter offset > "; IOFFSET
70 IF DEC\$ = "d" THEN IOFFSET = 26-IOFFSET: TYPE\$ = "ciphertext "
110 PRINT "Enter "+TYPE\$+"> ";
150 FOR I = 1 TO LONGITUD
170   IF ITEMP > 64 AND ITEMP < 91 THEN ITEMP = ((ITEMP-65)+IOFFSET) MOD 26 :  PRINT CHR\$(ITEMP+65); : ELSE PRINT CHR\$(ITEMP);
230 NEXT I
240 PRINT
250 END
```

### MSX Basic

Works with: MSX BASIC version any

The GW-BASIC solution works without any changes.

```beads 1 program 'Caesar cipher'
calc main_init
var str = "The five boxing wizards (🤖) jump quickly."
log "Plain: {str}"
str = Encrypt(str, 3)
log "Encrypted: {str}"
str = Decrypt(str, 3)
log "Decrypted: {str}"

//  encrypt a string by shifting the letters over by a number of slots
//  pass through any characters that are not in the Roman alphabet
calc Encrypt(
input:str  --- string to encrypt
nshift	 --- number of characters to slide over
) : str	--- encrypted string

var newStr = ""
loop from:1 to:str_len(input) count:myCount
var unicode : num = from_char(subset(input, from:myCount, len:1))
if unicode >= 65 and unicode <= 90
unicode = mod((unicode - 65 + nshift), 26) + 65
elif unicode >= 97 and unicode <= 122
unicode = mod((unicode - 97 + nshift), 26) + 97
newStr = newStr & to_char(unicode)
return newStr

//   undo the encryption
calc Decrypt(
input:str
nshift
) : str
//  we could also just shift by 26-nshift, same as going in reverse
return Encrypt(input, -nshift)```
Output:
```Plain: The five boxing wizards (🤖) jump quickly.
Encrypted: Wkh ilyh eralqj zlcdugv (🤖) mxps txlfnob.
Decrypted: The five boxing wizards (🤖) jump quickly.
```

## Befunge

Almost direct copy of the Vigenère cipher, although the code has been reversed and the first line eliminated because of the simpler key initialisation.

The text to encrypt is read from stdin, and the key is the first integer on the stack - 11 (65+) in the example below.

```65+>>>>10p100p1>:v:+>#*,#g1#0-#0:#!<<
"`"::_@#!`\*84:<~<\$<^+"A"%*2+9<v"{"\`
**-"A"-::0\`\55*`+#^_\0g+"4"+4^>\`*48
```
Output:
```The quick brown fox jumped over the lazy dogs
ESPBFTNVMCZHYQZIUFXAPOZGPCESPWLKJOZRD```

The decrypter is essentially identical, except for a change of sign on the last line.

```65+>>>>10p100p1>:v:+>#*,#g1#0-#0:#!<<
"`"::_@#!`\*84:<~<\$<^+"A"%*2+9<v"{"\`
**-"A"-::0\`\55*`+#^_\0g-"4"+4^>\`*48
```
Output:
```ESPBFTNVMCZHYQZIUFXAPOZGPCESPWLKJOZRD
THEQUICKBROWNFOXJUMPEDOVERTHELAZYDOGS```

## BQN

```o ← @‿'A'‿@‿'a'‿@ ⋄ m ← 5⥊↕2 ⋄ p ← m⊏∞‿26
Rot ← {i←⊑"A[a{"⍋𝕩 ⋄ i⊑o+p|(𝕨×m)+𝕩-o}⎉0
```

Example:

```3 Rot "We're no strangers to love // You know the rules and so do I"
```
`"Zh'uh qr vwudqjhuv wr oryh // Brx nqrz wkh uxohv dqg vr gr L"`

## Brainf***

```                                    Author: Ettore Forigo | Hexwell

+                                   start the key input loop
[
memory: | c | 0 | cc | key |
^

,                               take one character of the key

:c : condition for further ifs
!= ' ' (subtract 32 (ascii for ' '))
--------------------------------

(testing for the condition deletes it so duplication is needed)
[>>+<+<-]                       duplicate
>                               |
[<+>-]                          |
>                               |  :cc : copy of :c

[                               if :cc
|
>                           |  :key : already converted digits
|
[>++++++++++<-]             |  multiply by 10
>                           |  |
[<+>-]                      |  |
<                           |  |
|
<                           |  :cc
[-]                         |  clear (making the loop an if)
]                               |

<<                              :c

[>>+<+<-]                       duplicate
>                               |
[<+>-]                          |
>                               |  :cc

[                               if :cc
----------------            |  subtract 16 (difference between ascii for ' ' (already subtracted before) and ascii for '0'
|    making '0' 0; '1' 1; etc to transform ascii to integer)
|
[>+<-]                      |  move/add :cc to :key
]                               |

<<                              :c
]

memory: | 0 | 0 | 0 | key |
^

>>>                                 :key

[<<<+>>>-]                          move key

memory: | key | 0 | 0 | 0 |
^
<                                                       ^
+                                   start the word input loop
[
memory: | key | 0 | c | 0 | cc |
^

,                               take one character of the word

:c : condition for further if
!= ' ' (subtract 32 (ascii for ' '))
--------------------------------

[>>+<+<-]                       duplicate
>                               |
[<+>-]                          |
>                               |  :cc : copy of :c

[                               if :cc
|  subtract 65 (difference between ascii for ' ' (already subtracted before) and ascii for 'a'; making a 0; b 1; etc)
-----------------------------------------------------------------
|
<<<<                        |  :key
|
[>>>>+<<<+<-]               |  add :key to :cc := :shifted
>                           |  |
[<+>-]                      |  |
|
|  memory: | key | 0 | c | 0 | cc/shifted | 0 | 0 | 0 | 0 | 0 | divisor |
|                  ^
|
>>>>>>>>>                   |  :divisor
++++++++++++++++++++++++++  |  = 26
|
<<<<<<                      |  :shifted
|
|  memory: | shifted/remainder | 0 | 0 | 0 | 0 | 0 | divisor |
|                   ^
|
|  shifted % divisor
[                           |  |  while :remainder
|  |  |
|  |  |  memory: | shifted | 0 | 0 | 0 | 0 | 0 | divisor | 0 |
|  |  |               ^
|  |  |
[>>>>>>>+<<<<+<<<-]     |  |  |  duplicate :cshifted : copy of shifted
|  |  |
|  |  |  memory: | 0 | 0 | 0 | shifted | 0 | 0 | divisor | cshifted |
|  |  |            ^
>>>>>>                  |  |  |  :divisor                                   ^
|  |  |
[<<+>+>-]               |  |  |  duplicate
<                       |  |  |  |
[>+<-]                  |  |  |  |
<                       |  |  |  |  :cdiv : copy of divisor
|  |  |
|  |  |  memory: | 0 | 0 | 0 | shifted | cdiv | 0 | divisor | cshifted |
|  |  |                                    ^
|  |  |
|  |  |  subtract :cdiv from :shifted until :shifted is 0
[                       |  |  |  |  while :cdiv
<                   |  |  |  |  |  :shifted
|  |  |  |  |
[<<+>+>-]           |  |  |  |  |  duplicate
<                   |  |  |  |  |  |
[>+<-]              |  |  |  |  |  |
<                   |  |  |  |  |  | :csh
|  |  |  |  |
|  |  |  |  |  memory: | 0 | csh | 0 | shifted/remainder | cdiv | 0 | divisor | cshifted |
|  |  |  |  |                 ^
|  |  |  |  |
|  |  |  |  |  subtract 1 from :shifted if not 0
[                   |  |  |  |  |  |  if :csh
>>-<<           |  |  |  |  |  |  |  subtract 1 from :shifted
[-]             |  |  |  |  |  |  |  clear
]                   |  |  |  |  |  |  |
|  |  |  |  |
>>>                 |  |  |  |  |  :cdiv
-                   |  |  |  |  |  subtract 1
]                       |  |  |  |  |
|  |  |
|  |  |
|  |  |  memory: | 0 | 0 | 0 | remainder | 0 | 0 | divisor | cshifted |
|  |  |                                    ^
<                       |  |  |  :remainder                ^
|  |  |
[>+<<<<+>>>-]           |  |  |  duplicate
|  |  |
|  |  |  memory: | remainder | 0 | 0 | 0 | crem | 0 | divisor | shifted/modulus |
|  |  |                                ^
>                       |  |  |  :crem                               ^
|  |  |
|  |  |  clean up modulus if a remainder is left
[                       |  |  |  if :crem
>>>[-]<<<           |  |  |  |  clear :modulus
[-]                 |  |  |  |  clear
]                       |  |  |  |
|  |  |
|  |  |  if subtracting :cdiv from :shifted left a remainder we need to do continue subtracting;
|  |  |  otherwise modulus is the modulus between :divisor and :shifted
|  |  |
<<<<                    |  |  |  :remainder
]                           |  |  |
|
|  memory: | 0 | 0 | 0 | 0 | 0 | 0 | divisor | modulus | 0 | cmod | eq26 |
|            ^
|
>>>>>>>                     |  :modulus
|
[>>+<+<-]                   |  duplicate
>                           |  |
[<+>-]                      |  |
>                           |  |  :cmod : copy of :modulus
|
|  memory: | 0 | 0 | 0 | 0 | 0 | 0 | divisor | modulus | 0 | cmod | eq26 |
|                                                              ^
|
--------------------------  |  subtract 26
|
>                           |  :eq26 : condition equal to 26
+                           |  add 1 (set true)
|
<                           |  :cmod
[                           |  if :cmod not equal 26
>-<                     |  |  subtract 1 from :eq26 (set false)
[-]                     |  |  clear
]                           |  |
|
>                           |  :eq26
|
[                           |  if :eq26
<<<[-]>>>               |  |  clear :modulus
[-]                     |  |  clear
]                           |  |
|
|  the modulus operation above gives 26 as a valid modulus; so this is a workaround for setting a
|  modulus value of 26 to 0
|
<<<<                        |
[-]                         |  clear :divisor
|
|  memory: | c | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | modulus |
|                                            ^
>                           |  :modulus                                         ^
[<<<<<<<+>>>>>>>-]          |  move :modulus
|
|  memory: | c | 0 | modulus/cc | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
|                                                         ^
<<<<<<<                     |  :modulus/cc            ^
|
|  add 97 (ascii for 'a'; making 0 a; 1 b; etc)
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
.                           |  print
[-]                         |  clear
]                               |

memory: | c | 0 | modulus/cc |
^
<<                                 :c     ^
]
```

Usage: Give to the program the key and the word to encrypt, each followed by a space.
Input:

`10 abc`

Output:

`klm`

Input:

`16 klm`

Output:

`abc`

## C

```#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>

#define caesar(x) rot(13, x)
#define decaesar(x) rot(13, x)
#define decrypt_rot(x, y) rot((26-x), y)

void rot(int c, char *str)
{
int l = strlen(str);

const char*  alpha_low  = "abcdefghijklmnopqrstuvwxyz";

const char*  alpha_high = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

char subst;  /* substitution character */
int idx;    /* index */

int i; /* loop var */

for (i = 0; i < l; i++)  /* for each letter in string */
{
if( 0 == isalpha(str[i]) )  continue; /* not alphabet character */

idx = (int) (tolower(str[i]) - 'a') + c) % 26; /* compute index */

if( isupper(str[i]) )
subst = alpha_high[idx];
else
subst = alpha_low[idx];

str[i] = subst;

}
}

int main(int argc, char** argv)
{
char str[] = "This is a top secret text message!";

printf("Original: %s\n", str);
caesar(str);
printf("Encrypted: %s\n", str);
decaesar(str);
printf("Decrypted: %s\n", str);

return 0;
}
```

## C#

```using System;
using System.Linq;

namespace CaesarCypher
{
class Program
{
static char Encrypt(char ch, int code)
{
if (!char.IsLetter(ch)) return ch;

char offset = char.IsUpper(ch) ? 'A' : 'a';
return (char)((ch + code - offset) % 26 + offset);
}

static string Encrypt(string input, int code)
{
return new string(input.Select(ch => Encrypt(ch, code)).ToArray());
}

static string Decrypt(string input, int code)
{
return Encrypt(input, 26 - code);
}

const string TestCase = "Pack my box with five dozen liquor jugs.";

static void Main()
{
string str = TestCase;

Console.WriteLine(str);
str = Encrypt(str, 5);
Console.WriteLine("Encrypted: " + str);
str = Decrypt(str, 5);
Console.WriteLine("Decrypted: " + str);
}
}
}
```
Output:
```Pack my box with five dozen liquor jugs.
Encrypted: Ufhp rd gtc bnym knaj itejs qnvztw ozlx.
Decrypted: Pack my box with five dozen liquor jugs.```

## C++

```#include <string>
#include <iostream>
#include <algorithm>
#include <cctype>

class MyTransform {
private :
int shift ;
public :
MyTransform( int s ) : shift( s ) { }

char operator( )( char c ) {
if ( isspace( c ) )
return ' ' ;
else {
static std::string letters( "abcdefghijklmnopqrstuvwxyz" ) ;
std::string::size_type found = letters.find(tolower( c )) ;
int shiftedpos = ( static_cast<int>( found ) + shift ) % 26 ;
if ( shiftedpos < 0 ) //in case of decryption possibly
shiftedpos = 26 + shiftedpos ;
char shifted = letters[shiftedpos] ;
return shifted ;
}
}
} ;

int main( ) {
std::string input ;
std::cout << "Which text is to be encrypted ?\n" ;
getline( std::cin , input ) ;
std::cout << "shift ?\n" ;
int myshift = 0 ;
std::cin >> myshift ;
std::cout << "Before encryption:\n" << input << std::endl ;
std::transform ( input.begin( ) , input.end( ) , input.begin( ) ,
MyTransform( myshift ) ) ;
std::cout << "encrypted:\n" ;
std::cout << input << std::endl ;
myshift *= -1 ; //decrypting again
std::transform ( input.begin( ) , input.end( ) , input.begin( ) ,
MyTransform( myshift ) ) ;
std::cout << "Decrypted again:\n" ;
std::cout << input << std::endl ;
return 0 ;
}
```
Output:
```Which text is to be encrypted ?
this is an interesting text
shift ?
3
Before encryption:
this is an interesting text
encrypted:
wklv lv dq lqwhuhvwlqj whaw
Decrypted again:
this is an interesting text
```

Alternative version - lambda functions, auto, iterators

#### Works with: C++-11

```/* caesar cipher */

#include <string>
#include <iostream>
#include <cctype>

int main( ) {

using namespace std;

string input ;
int key = 0;

// lambda functions

auto encrypt = [&](char c, int key ) {
char A  = ( islower(c) )? 'a': 'A';
c = (isalpha(c))? (c - A + key) % 26 + A : c;
return (char) c;
};

auto decrypt = [&](char c, int key ) {
char A  = ( islower(c) )? 'a': 'A';
c = (isalpha(c))? (c - A + (26 - key) ) % 26 + A : c;
return (char) c;
};

cout << "Enter a line of text.\n";
getline( cin , input );

cout << "Enter an integer to shift text.\n";
cin  >> key;

while ( (key < 1) || (key > 25) )
{
cout << "must be an integer between 1 and 25 -->" << endl;
cin  >> key;
}

cout << "Plain:    \t" << input << endl ;

for ( auto & cp : input)    // use & for mutability
cp = encrypt(cp, key);

cout << "Encrypted:\t" << input << endl;

for ( auto & cp : input)
cp = decrypt(cp, key);

cout << "Decrypted:\t" << input << endl;

return 0 ;
}
```
Output:
```Enter a line of text.
This is a line of plain text, 50 characters long.
Enter an integer to shift text.
5
Plain:    	This is a line of plain text, 50 characters long.
Encrypted:	Ymnx nx f qnsj tk uqfns yj}y1 :5 hmfwfhyjwx qtsl3
Decrypted:	This is a line of plain text, 50 characters long.
```

## Clojure

```(defn encrypt-character [offset c]
(if (Character/isLetter c)
(let [v (int c)
base (if (>= v (int \a))
(int \a)
(int \A))
offset (mod offset 26)] ;works with negative offsets too!
(char (+ (mod (+ (- v base) offset) 26)
base)))
c))

(defn encrypt [offset text]
(apply str (map #(encrypt-character offset %) text)))

(defn decrypt [offset text]
(encrypt (- 26 offset) text))

(let [text "The Quick Brown Fox Jumps Over The Lazy Dog."
enc (encrypt -1 text)]
(print "Original text:" text "\n")
(print "Encryption:" enc "\n")
(print "Decryption:" (decrypt -1 enc) "\n"))
```

output:

```Original text: The Quick Brown Fox Jumps Over The Lazy Dog.
Encryption: Sgd Pthbj Aqnvm Enw Itlor Nudq Sgd Kzyx Cnf.
Decryption: The Quick Brown Fox Jumps Over The Lazy Dog.```

Terser version using replace:

```(defn encode [k s]
(let [f #(take 26 (drop %3 (cycle (range (int %1) (inc (int %2))))))
a #(map char (concat (f \a \z %) (f \A \Z %)))]
(apply str (replace (zipmap (a 0) (a k)) s))))

(defn decode [k s]
(encode (- 26 k) s))
```

output:

```(encode 12 "The Quick Brown Fox jumped over the lazy dog")
=> "Ftq Cguow Ndaiz Raj vgybqp ahqd ftq xmlk pas"
(decode 12 (encode 12 "The Quick Brown Fox jumped over the lazy dog"))
=> "The Quick Brown Fox jumped over the lazy dog"
```

Fast version, using str/escape:

```(defn fast-caesar [n s]
(let [m (mod n 26)
upper (map char (range 65 91))
upper->new (zipmap upper (drop m (cycle upper)))
lower (map char (range 97 123))
lower->new (zipmap lower (drop m (cycle lower)))]
(clojure.string/escape s (merge upper->new lower->new))))
```

output:

```(fast-caesar 12 "The Quick Brown Fox jumped over the lazy dog")
=> "Ftq Cguow Ndaiz Raj vgybqp ahqd ftq xmlk pas"
```

## COBOL

COBOL-85 ASCII or EBCIDIC

```       IDENTIFICATION DIVISION.
PROGRAM-ID. CAESAR.

DATA DIVISION.
WORKING-STORAGE SECTION.
01  MSG        PIC X(50)
VALUE "The quick brown fox jumped over the lazy dog.".
01  OFFSET     PIC 9(4) VALUE 7 USAGE BINARY.
01  FROM-CHARS PIC X(52).
01  TO-CHARS   PIC X(52).
01  TABL.
02         PIC X(26) VALUE "abcdefghijklmnopqrstuvwxyz".
02         PIC X(26) VALUE "ABCDEFGHIJKLMNOPQRSTUVWXYZ".
02         PIC X(26) VALUE "abcdefghijklmnopqrstuvwxyz".
02         PIC X(26) VALUE "ABCDEFGHIJKLMNOPQRSTUVWXYZ".

PROCEDURE DIVISION.
BEGIN.
DISPLAY MSG
PERFORM ENCRYPT
DISPLAY MSG
PERFORM DECRYPT
DISPLAY MSG
STOP RUN.

ENCRYPT.
MOVE TABL (1:52) TO FROM-CHARS
MOVE TABL (1 + OFFSET:52) TO TO-CHARS
INSPECT MSG CONVERTING FROM-CHARS TO TO-CHARS.

DECRYPT.
MOVE TABL (1 + OFFSET:52) TO FROM-CHARS
MOVE TABL (1:52) TO TO-CHARS
INSPECT MSG CONVERTING FROM-CHARS TO TO-CHARS.

END PROGRAM CAESAR.
```
Output:
```The quick brown fox jumped over the lazy dog.
aol xBpjr iyvDu mvE qBtwlk vCly Aol shGF kvn.
The quick brown fox jumped over the lazy dog.
```
Works with: COBOL 2002
```       >>SOURCE FORMAT IS FREE
IDENTIFICATION DIVISION.
PROGRAM-ID. caesar-cipher.

ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
REPOSITORY.
FUNCTION encrypt
FUNCTION decrypt.

DATA DIVISION.
WORKING-STORAGE SECTION.
01  plaintext                 PIC X(50).
01  offset                    USAGE BINARY-CHAR.
01  encrypted-str             PIC X(50).

PROCEDURE DIVISION.
DISPLAY "Enter a message to encrypt: " WITH NO ADVANCING
ACCEPT plaintext
DISPLAY "Enter the amount to shift by: " WITH NO ADVANCING
ACCEPT offset
MOVE encrypt(offset, plaintext) TO encrypted-str
DISPLAY "Encrypted: " encrypted-str
DISPLAY "Decrypted: " decrypt(offset, encrypted-str).

END PROGRAM caesar-cipher.

IDENTIFICATION DIVISION.
FUNCTION-ID. encrypt.

ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
REPOSITORY.
FUNCTION ALL INTRINSIC.

DATA DIVISION.
LOCAL-STORAGE SECTION.
01  i                         USAGE INDEX.
01  a                         USAGE BINARY-CHAR.
01  offset                    USAGE BINARY-CHAR.
01  str                       PIC X(50).
01  encrypted-str             PIC X(50).

PROCEDURE DIVISION USING offset, str RETURNING encrypted-str.
PERFORM VARYING i FROM 1 BY 1 UNTIL i > LENGTH(str)
IF str(i:1) IS NOT ALPHABETIC OR str(i:1) = SPACE
MOVE str(i:1) TO encrypted-str(i:1)
EXIT PERFORM CYCLE
END-IF
IF str(i:1) IS ALPHABETIC-UPPER
MOVE ORD("A") TO a
ELSE
MOVE ORD("a") TO a
END-IF
MOVE CHAR(MOD(ORD(str(i:1)) - a + offset, 26) + a)
TO encrypted-str(i:1)
END-PERFORM
EXIT FUNCTION.

END FUNCTION encrypt.

IDENTIFICATION DIVISION.
FUNCTION-ID. decrypt.

ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
REPOSITORY.
FUNCTION encrypt.

DATA DIVISION.
LOCAL-STORAGE SECTION.
01  decrypt-offset            USAGE BINARY-CHAR.
01  offset                    USAGE BINARY-CHAR.
01  str                       PIC X(50).
01  decrypted-str             PIC X(50).

PROCEDURE DIVISION USING offset, str RETURNING decrypted-str.
SUBTRACT offset FROM 26 GIVING decrypt-offset
MOVE encrypt(decrypt-offset, str) TO decrypted-str
EXIT FUNCTION.

END FUNCTION decrypt.
```
Output:
```Enter a message to encrypt: The quick brown fox jumps over the lazy dog.
Enter the amount to shift by: 7
Encrypted: Aol xbpjr iyvdu mve qbtwz vcly aol shgf kvn.
Decrypted: The quick brown fox jumps over the lazy dog.
```

## CoffeeScript

```cipher = (msg, rot) ->
msg.replace /([a-z|A-Z])/g, (\$1) ->
c = \$1.charCodeAt(0)
String.fromCharCode \
if c >= 97
then (c + rot + 26 - 97) % 26 + 97
else (c + rot + 26 - 65) % 26 + 65

console.log cipher "Hello World", 2
console.log cipher "azAz %^&*()", 3
```
Output:
```> coffee foo.coffee
Jgnnq Yqtnf
dcDc %^&*()
```

## Commodore BASIC

Very generic implementation. Please note that in Commodore BASIC, SHIFT-typed letters (to generate either graphic symbols in upper-case mode, or capital letters in lower-case mode) do not translate to PETSCII characters 97 through 122, but instead to characters 193 through 218.

```1 rem caesar cipher
2 rem rosetta code
10 print chr\$(147);chr\$(14);
15 input "Enter a key value from 1 to 25";kv
20 if kv<1 or kv>25 then print "Out of range.":goto 15
25 gosub 1000
30 print chr\$(147);"Enter a message to translate."
35 print:print "Press CTRL-Z when finished.":print
40 mg\$="":gosub 2000
45 print chr\$(147);"Processing...":gosub 3000
50 print chr\$(147);"The translated message is:"
55 print:print cm\$
100 print:print "Do another one? ";
110 get k\$:if k\$<>"y" and k\$<>"n" then 110
120 print k\$:if k\$="y" then goto 10
130 end

1000 rem generate encoding table
1010 ec\$=""
1015 rem lower case
1020 for i=kv to 26:ec\$=ec\$+chr\$(i+64):next i
1021 for i=1 to kv-1:ec\$=ec\$+chr\$(i+64):next i
1025 rem upper case
1030 for i=kv to 26:ec\$=ec\$+chr\$(i+192):next i
1031 for i=1 to kv-1:ec\$=ec\$+chr\$(i+192):next i
1099 return

2000 rem get user input routine
2005 print chr\$(18);" ";chr\$(146);chr\$(157);
2010 get k\$:if k\$="" then 2010
2012 if k\$=chr\$(13) then print " ";chr\$(157);
2015 print k\$;
2020 if k\$=chr\$(20) then mg\$=left\$(mg\$,len(mg\$)-1):goto 2040
2025 if len(mg\$)=255 or k\$=chr\$(26) then return
2030 mg\$=mg\$+k\$
2040 goto 2005

3000 rem translate message
3005 cm\$=""
3010 for i=1 to len(mg\$)
3015 c=asc(mid\$(mg\$,i,1))
3020 if c<65 or (c>90 and c<193) or c>218 then cm\$=cm\$+chr\$(c):goto 3030
3025 if c>=65 and c<=90 then c=c-64
3030 if c>=193 and c<=218 then c=(c-192)+26
3035 cm\$=cm\$+mid\$(ec\$,c,1)
3040 next i
3050 return
```
Output:
```Enter a key value from 1 to 25? 10

Enter a message to translate.

Press CTRL-Z when finished.

You know it is going to be a bad day
when the letters in your alphabet soup
spell D-I-S-A-S-T-E-R.

Processing...

The translated message is:

Iye uxyg sd sc qysxq dy lo k lkn nki
grox dro voddobc sx iyeb kvzrklod cyez
czovv N-S-C-K-C-D-O-B.

Do another one? n

█
```

## Common Lisp

#### Main version

```(defun encipher-char (ch key)
(let* ((c  (char-code  ch)) (la (char-code #\a)) (ua (char-code #\A))
(base (cond ((<= la c (char-code #\z)) la)
((<= ua c (char-code #\Z)) ua)
(nil))))
(if base (code-char (+ (mod (+ (- c base) key) 26) base)) ch)))

(defun caesar-cipher (str key)
(map 'string #'(lambda (c) (encipher-char c key)) str))

(defun caesar-decipher (str key) (caesar-cipher str (- key)))

(let* ((original-text "The five boxing wizards jump quickly")
(key 3)
(cipher-text (caesar-cipher original-text key))
(recovered-text (caesar-decipher cipher-text key)))
(format t " Original: ~a ~%" original-text)
(format t "Encrypted: ~a ~%" cipher-text)
(format t "Decrypted: ~a ~%" recovered-text))
```
Output:
``` Original: The five boxing wizards jump quickly
Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted: The five boxing wizards jump quickly```
```(defun caesar-encipher (s k)
(map 'string #'(lambda (c) (z c k)) s))

(defun caesar-decipher (s k) (caesar-encipher s (- k)))

(defun z (h k &aux (c (char-code  h))
(b (or (when (<= 97 c 122) 97)
(when (<= 65 c 90) 65))))
(if b (code-char (+ (mod (+ (- c b) k) 26) b)) h))
```
Output:
```> (caesar-encipher "The quick brown fox jumps over the lazy dog" 23)
"Qeb nrfzh yoltk clu grjmp lsbo qeb ixwv ald"
> (caesar-decipher "Qeb nrfzh yoltk clu grjmp lsbo qeb ixwv ald" 23)
"The quick brown fox jumps over the lazy dog"```

#### Alternate version

1. Program

```(defconstant +a+ "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz")

(defun caesar (txt offset)
(map 'string
#'(lambda (c)
(if (find c +a+)
(char +a+ (mod (+ (position c +a+) (* 2 offset)) 52))
c))
txt))
```

2. Execution

Output:
```(caesar "Ave Caesar morituri te salutant" 13)
Nir Pnrfne zbevghev gr fnyhgnag
(caesar "Nir Pnrfne zbevghev gr fnyhgnag" -13)
Ave Caesar morituri te salutant```

## Crystal

```class String
ALPHABET = ("A".."Z").to_a

def caesar_cipher(num)
self.tr(ALPHABET.join, ALPHABET.rotate(num).join)
end
end

# demo
encrypted = "THEQUICKBROWNFOXJUMPSOVERTHELAZYDOG".caesar_cipher(5)
decrypted = encrypted.caesar_cipher(-5)
```

## Cubescript

```alias modn [ mod (+ (mod \$arg1 \$arg2) \$arg2) \$arg2 ]
//Cubescript's built-in mod will fail on negative numbers

alias cipher [
push alpha [
"A B C D E F G H I J K L M N O P Q R S T U V W X Y Z"
"a b c d e f g h i j k l m n o p q r s t u v w x y z"
] [ push chars [] [
loop i (strlen \$arg1) [
looplist n \$alpha [
if (! (listlen \$chars)) [
alias chars (? (> (listindex \$n (substr \$arg1 \$i 1)) -1) \$n [])
]
]
alias arg1 (
concatword (substr \$arg1 0 \$i) (
? (> (listindex \$chars (substr \$arg1 \$i 1)) -1) (
at \$chars (
modn (+ (
listindex \$chars (substr \$arg1 \$i 1)
) \$arg2) (listlen \$chars)
)
) (substr \$arg1 \$i 1)
) (substr \$arg1 (+ \$i 1) (strlen \$arg1))
)
alias chars []
]
] ]
result \$arg1
]

alias decipher [
push alpha [
"A B C D E F G H I J K L M N O P Q R S T U V W X Y Z"
"a b c d e f g h i j k l m n o p q r s t u v w x y z"
] [ push chars [] [
loop i (strlen \$arg1) [
looplist n \$alpha [
if (! (listlen \$chars)) [
alias chars (? (> (listindex \$n (substr \$arg1 \$i 1)) -1) \$n [])
]
]
alias arg1 (
concatword (substr \$arg1 0 \$i) (
? (> (listindex \$chars (substr \$arg1 \$i 1)) -1) (
at \$chars (
modn (- (
listindex \$chars (substr \$arg1 \$i 1)
) \$arg2 ) (listlen \$chars)
)
) (substr \$arg1 \$i 1)
) (substr \$arg1 (+ \$i 1) (strlen \$arg1))
)
alias chars []
]
] ]
result \$arg1
]```

Usage:

```>>> cipher "The Quick Brown Fox Jumps Over The Lazy Dog." 5
> Ymj Vznhp Gwtbs Ktc Ozrux Tajw Ymj Qfed Itl.
>>> decipher "Ymj Vznhp Gwtbs Ktc Ozrux Tajw Ymj Qfed Itl." 5
> The Quick Brown Fox Jumps Over The Lazy Dog.
```

## D

```import std.stdio, std.traits;

S rot(S)(in S s, in int key) pure nothrow @safe
if (isSomeString!S) {
auto res = s.dup;

foreach (immutable i, ref c; res) {
if ('a' <= c && c <= 'z')
c = ((c - 'a' + key) % 26 + 'a');
else if ('A' <= c && c <= 'Z')
c = ((c - 'A' + key) % 26 + 'A');
}
return res;
}

void main() @safe {
enum key = 3;
immutable txt = "The five boxing wizards jump quickly";
writeln("Original:  ", txt);
writeln("Encrypted: ", txt.rot(key));
writeln("Decrypted: ", txt.rot(key).rot(26 - key));
}
```
Output:
```Original:  The five boxing wizards jump quickly
Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted: The five boxing wizards jump quickly```

Simpler in-place version (same output):

```import std.stdio, std.ascii;

void inplaceRot(char[] txt, in int key) pure nothrow {
foreach (ref c; txt) {
if (isLower(c))
c = (c - 'a' + key) % 26 + 'a';
else if (isUpper(c))
c = (c - 'A' + key) % 26 + 'A';
}
}

void main() {
enum key = 3;
auto txt = "The five boxing wizards jump quickly".dup;
writeln("Original:  ", txt);
txt.inplaceRot(key);
writeln("Encrypted: ", txt);
txt.inplaceRot(26 - key);
writeln("Decrypted: ", txt);
}
```

A version that uses the standard library (same output):

```import std.stdio, std.ascii, std.string, std.algorithm;

string rot(in string s, in int key) pure nothrow @safe {
auto uppr = uppercase.dup.representation;
bringToFront(uppr[0 .. key], uppr[key .. \$]);
auto lowr = lowercase.dup.representation;
bringToFront(lowr[0 .. key], lowr[key .. \$]);
return s.translate(makeTrans(letters, assumeUTF(uppr ~ lowr)));
}

void main() {
enum key = 3;
immutable txt = "The five boxing wizards jump quickly";
writeln("Original:  ", txt);
writeln("Encrypted: ", txt.rot(key));
writeln("Decrypted: ", txt.rot(key).rot(26 - key));
}
```

## Dart

```class Caesar {
int _key;

Caesar(this._key);

int _toCharCode(String s) {
return s.charCodeAt(0);
}

String _fromCharCode(int ch) {
return new String.fromCharCodes([ch]);
}

String _process(String msg, int offset) {
StringBuffer sb=new StringBuffer();
for(int i=0;i<msg.length;i++) {
int ch=msg.charCodeAt(i);
if(ch>=_toCharCode('A')&&ch<=_toCharCode('Z')) {
}
else if(ch>=_toCharCode('a')&&ch<=_toCharCode('z')) {
} else {
}
}
return sb.toString();
}

String encrypt(String msg) {
return _process(msg, _key);
}

String decrypt(String msg) {
return _process(msg, 26-_key);
}
}

void trip(String msg) {
Caesar cipher=new Caesar(10);

String enc=cipher.encrypt(msg);
String dec=cipher.decrypt(enc);
print("\"\$msg\" encrypts to:");
print("\"\$enc\" decrypts to:");
print("\"\$dec\"");
Expect.equals(msg,dec);
}

main() {
Caesar c2=new Caesar(2);
print(c2.encrypt("HI"));
Caesar c20=new Caesar(20);
print(c20.encrypt("HI"));

// try a few roundtrips

trip("");
trip("A");
trip("z");
trip("Caesar cipher");
trip(".-:/\"\\!");
trip("The Quick Brown Fox Jumps Over The Lazy Dog.");
}
```
Output:
```JK
BC
"" encrypts to:
"" decrypts to:
""
"A" encrypts to:
"K" decrypts to:
"A"
"z" encrypts to:
"j" decrypts to:
"z"
"Caesar cipher" encrypts to:
"Mkockb mszrob" decrypts to:
"Caesar cipher"
".-:/"\!" encrypts to:
".-:/"\!" decrypts to:
".-:/"\!"
"The Quick Brown Fox Jumps Over The Lazy Dog." encrypts to:
"Dro Aesmu Lbygx Pyh Tewzc Yfob Dro Vkji Nyq." decrypts to:
"The Quick Brown Fox Jumps Over The Lazy Dog."```

See #Pascal.

## Dyalect

Translation of: C#
```func Char.Encrypt(code) {
if !this.IsLetter() {
return this
}
var offset = (this.IsUpper() ? 'A' : 'a').Order()
return Char((this.Order() + code - offset) % 26 + offset)
}

func String.Encrypt(code) {
var xs = []
for c in this {
}
return String.Concat(values: xs)
}

func String.Decrypt(code) {
this.Encrypt(26 - code);
}

var str = "Pack my box with five dozen liquor jugs."
print(str)
str = str.Encrypt(5)
print("Encrypted: \(str)")
str = str.Decrypt(5)
print("Decrypted: \(str)")```
Output:
```Pack my box with five dozen liquor jugs.
Encrypted: Ufhp rd gtc bnym knaj itejs qnvztw ozlx.
Decrypted: Pack my box with five dozen liquor jugs.```

## EasyLang

```func\$ crypt str\$ key .
for c\$ in strchars str\$
c = strcode c\$
if c >= 65 and c <= 90
c = (c + key - 65) mod 26 + 65
elif c >= 97 and c <= 122
c = (c + key - 97) mod 26 + 97
.
enc\$ &= strchar c
.
return enc\$
.
enc\$ = crypt "Rosetta Code" 4
print enc\$
print crypt enc\$ -4
```

## EDSAC order code

The EDSAC had only upper-case letters, which were represented by 5-bit codes. From a programming point of view the assignment of codes to letters was random, so tables are used to convert between EDSAC code and alphabetic position.

In this program, the alphabetic shift to encipher or decipher a message is specified by adding the translation of 'A' to the beginning of the message. For instance, if encipherment shifts letters 3 forward then the message should be prefixed with 'D' to encipher, or 'X' to decipher.

The program prints a test message, enciphered and deciphered, and then prompts for further messages. If the program is running in the EdsacPC simulator, the user can enter a message by storing it in a text file, making that file the active file, and clicking Reset. The message must be terminated by a blank row of tape (represented by '.' in EdsacPC).

```  [Caesar cipher for Rosetta Code.
EDSAC program, Initial Orders 2.]

[Table for converting alphabetic position 0..25 to EDSAC code.
The EDSAC code is in the high 5 bits.]
T   54 K [access table via C parameter]
P   56 F
T   56 K
AFBFCFDFEFFFGFHFIFJFKFLFMFNFOFPFQFRFSFTFUFVFWFXFYFZF

[Table for converting 5-bit EDSAC code to alphabetic position 0..25.
Computed at run time (so the programmer doesn't need to know the EDSAC codes).
32 entries; entry is -1 if the EDSAC code does not represent a letter.]
T   53 K [access table via B parameter]
P   82 F

[Subroutine to read string from input and
store with char codes in high 5 bits.
String is terminated by blank row of tape, which is stored.
22 locations; workspace: 4D]
T  114 K
GKA3FT19@AFA20@T10@I5FA4DR16FT4DA4FUFE14@A21@G18@T5FA10@A2FE4@T5FEFUFK2048F

[Subroutine to print string with character codes in high 5 bits.
String is terminated by blank row of tape, which is not printed.
18 locations; orkspace: 4F]
T  136 K
GKA3FT16@AFA2@T5@AFU4FE10@A17@G15@O4FT4FA5@A2FG4@TFEFK2048F

[Define start of user message]
T   47 K  [access message via M parameter]
P  350 F  [address of message]

T  154 K
G      K
[Constants]
[0]   P      M  [address of user message]
[1]   A      B
[2]   A      C
[3]   T      B
[4]   P   25 F
[5]   P   26 F
[6]   P   31 F
[7]   K 2048 F  [(1) letter shift (2) used in test for
blank row of tape at end of message]
[8]   @      F  [carriage return]
[9]   &      F  [line feed]
[10]   K 4096 F  [null char]

[Constant messages. Each includes new line at the end.]
[11]   TF EF SF TF IF NF GF @F &F K4096F
[21]   P   11 @
[22]   EF NF TF EF RF !F MF EF SF SF AF GF EF @F &F K4096F
[38]   P   22 @
[39]   MF UF SF TF !F SF TF AF RF TF !F WF IF TF HF !F BF !F TF OF !F ZF @F &F K4096F
[64]   P   39 @

[Subroutine to convert EDSAC code to alphabetic position.
Input:  4F holds EDSAC code in high 5 bits
Output: 4F holds alphabetic position (0..25, or -1 if not a letter).
Workspace: 5F]
[65]   A    3 F  [make jump for return]
T   75 @  [plant in code]
A    4 F  [load EDSAC code]
R  512 F  [shift code into address field]
T    5 F  [temp store]
C    5 F  [acc := address bits only]
A    1 @  [make order to load alphabetic position]
T   73 @  [plant in code]
[73]   A      B  [load alphabetic position]
T    4 F  [store in 4F]
[75]   E      F  [return]

[Subroutine to encipher or decipher a message by Caesar shift.
Input:  Message is accessed by the M parameter, and
terminated by a blank row of tape.
Output: 0F = error flag: 0 if OK, < 0 if error (bad message prefix)
Workspace 4F.]
[76]   A    3 F  [make jump for return]
T  119 @  [plant in code]
A   80 @  [load order to access first char]
T   95 @  [plant in code]
[80]   A      M  [load first char of message]
T    4 F  [pass to subroutine]
[82]   A   82 @  [get alphabetic position]
G   65 @
A    4 F  [load alphabetic position]
U      F  [to 0F for use as shift]
S    2 F  [check it's not 0 or -1]
G  118 @  [error exit if it is]
T    1 F  [clear acc]
S      F  [load negative of shift]
and convert rest of message]
[Here after skipping non-letter]
[91]   T    4 F  [clear acc]
[Here after converting letter]
A    2 F  [inc address to next character]
T   95 @  [store back]
[95]   A      M  [load char from message (in top 5 bits)]
E  100 @  [if >= 0 then not blank row]
A    7 @  [if < 0, test for blank row]
G  117 @  [jump out if so]
S    7 @  [restore after test]
[100]   T    4 F  [character to 4F for subroutine]
[101]   A  101 @  [for return from subroutine]
G   65 @  [sets 4F := alphabetic position]
A    4 F  [to acc]
G   91 @  [if < 0 then not a letter; don't change it]
A      F  [apply Caesar shift]
[Subtract 26 if required, so result is in range 0..25]
S    5 @  [subtract 26]
E  109 @  [skip next if result >= 0]
[108]   A    5 @  [add 26]
[109]   A    2 @  [make order to read EDSAC letter at that position]
T  114 @  [plant in code]
A   95 @  [load A order from above]
A   14 C  [add 'O F' to make T order]
T  115 @  [plant in code]
[114]   A      C  [load enciphered letter]
[115]   T      M  [overwrite original letter]
E   92 @  [loop back]
[117]   T      F  [flag = 0 for OK]
[118]   T      F  [flag to 0F: 0 if OK, < 0 if error]
[119]   E      F  [return with acc = 0]

[Subroutine to print encipered or deciphered message, plus new line]
[120]   A    3 F  [make jump order for return]
T  128 @  [plant in code]
T      F  [to 0F for print subroutine]
[124]   A  124 @
G  136 F  [print message, clears acc]
O    8 @  [print new line]
O    9 @
[128]   E      F  [return with acc = 0]

[Main routine]
[129]   O    7 @  [set letter shift]
H    6 @  [mult reg has this value throughout;
selects bits 1..5 of 17-bit value]
[Build inverse table from direct table
First initialize all 32 locations to -1]
A    6 @  [work backwards]
[132]   A    3 @  [make T order for inverse table]
T  135 @  [plant in code]
S    2 F  [make -1 in address field]
[135]   T      B  [store in inverse table]
A  135 @  [get T order]
S    3 @  [compare with start of table]
E  132 @  [loop till done]
[Now fill in entries by reversing direct table]
T      F  [clear acc]
A    4 @  [work backwards]
[142]   U    5 F  [index in 5F]
A    2 @  [make A order for direct table]
T  145 @  [plant in code]
[145]   A      C  [load entry from direct table, code in top 5 bits]
R  512 F  [shift 11 right, 5-bit code to address field]
T    4 F  [temp store]
C    4 F  [pick out 5-bit code]
A    3 @  [make T order for inverse table]
T  152 @  [plant in code]
[152]   T      B  [store in inverse table]
A    5 F  [load index again]
S    2 F  [update index]
E  142 @  [loop back]
[Here when inverse table is complete]
[156]   T      F  [clear acc]
T      F  [to 0F for print subroutine]
[159]   A  159 @
G  136 F  [print "testing message"]
[Loop back here to get message from user]
T      F  [to 0F for print subroutine]
[164]   A  164 @
G  136 F  [print prompt]
O   10 @  [print null to flush teleprinter buffer]
Z      F  [stop]
[First time here, read message from end of this file.
Later times, read message from file chosen by the user.]
T      F  [to 0F for input]
[170]   A  170 @
[172]   A  172 @
G  120 @  [print message]
[174]   A  174 @
G   76 @  [call Caesar shift subroutine]
E  184 @  [jump if OK]
T      F  [error, clear acc]
T      F
[181]   A  181 @
G  136 F  [print error message]
E  162 @  [back to try again]
[Here if message was enciphered without error]
[184]   A  184 @
G  120 @  [print enciphered message]
[186]   A  186 @
G   76 @  [call Caesar shift subroutine]
[188]   A  188 @
G  120 @  [print deciphered message]
E  162 @  [back for another message]
E  129 Z  [define entry point]
P      F  [acc = 0 on entry]
DGAZA!FREQUENS!LIBYCUM!DUXIT!KARTHAGO!TRIUMPHUM.```
Output:
```TESTING
DGAZA FREQUENS LIBYCUM DUXIT KARTHAGO TRIUMPHUM
XJDCD IUHTXHQV OLEBFXP GXALW NDUWKDJR WULXPSKXP
DGAZA FREQUENS LIBYCUM DUXIT KARTHAGO TRIUMPHUM
ENTER MESSAGE
WGALLIA EST OMNIS DIVISA IN PARTES TRES
ECWHHEW AOP KIJEO ZEREOW EJ LWNPAO PNAO
WGALLIA EST OMNIS DIVISA IN PARTES TRES
ENTER MESSAGE
```

## Eiffel

```class
APPLICATION

inherit
ARGUMENTS

create
make

feature {NONE} -- Initialization

make
-- Run application.
local
s: STRING_32
do
s := "The tiny tiger totally taunted the tall Till."
print ("%NString to encode: " + s)
print ("%NEncoded string: " + encode (s, 12))
print ("%NDecoded string (after encoding and decoding): " + decode (encode (s, 12), 12))
end

feature		-- Basic operations

decode (to_be_decoded: STRING_32; offset: INTEGER): STRING_32
-- Decode `to be decoded' according to `offset'.
do
Result := encode (to_be_decoded, 26 - offset)
end

encode (to_be_encoded: STRING_32; offset: INTEGER): STRING_32
-- Encode `to be encoded' according to `offset'.
local
l_offset: INTEGER
l_char_code: INTEGER
do
create Result.make_empty
l_offset := (offset \\ 26) + 26
across to_be_encoded as tbe loop
if tbe.item.is_alpha then
if tbe.item.is_upper then
l_char_code := ('A').code + (tbe.item.code - ('A').code + l_offset) \\ 26
Result.append_character (l_char_code.to_character_32)
else
l_char_code := ('a').code + (tbe.item.code - ('a').code + l_offset) \\ 26
Result.append_character (l_char_code.to_character_32)
end
else
Result.append_character (tbe.item)
end
end
end
end
```
Output:
```String to encode: The tiny tiger totally taunted the tall Till.
Encoded string: Ftq fuzk fusqd fafmxxk fmgzfqp ftq fmxx Fuxx.
Decoded string (after encoding and decoding): The tiny tiger totally taunted the tall Till.
```

## Ela

```open number char monad io string

chars = "ABCDEFGHIJKLMOPQRSTUVWXYZ"

caesar _ _ [] = ""
caesar op key (x::xs) = check shifted ++ caesar op key xs
where orig = indexOf (string.upper \$ toString x) chars
shifted = orig `op` key
check val | orig == -1 = x
| val > 24 = trans \$ val - 25
| val < 0 = trans \$ 25 + val
| else = trans shifted
trans idx = chars:idx

cypher = caesar (+)
decypher = caesar (-)

key = 2

do
putStrLn "A string to encode:"
putStr "Encoded string: "
cstr <- return <| cypher key str
put cstr
putStrLn ""
putStr "Decoded string: "
put \$ decypher key cstr```
Output:
```A string to encode:
HELLO! THIS IS A SECRET MESSAGE!
Encoded string: "JGOOQ! VJKU KU C UGETGV PGUUCIG!"
Decoded string: "HELLO! THIS IS A SECRET MESSAGE!"```

## Elena

ELENA 6.x :

```import system'routines;
import system'math;
import extensions;
import extensions'text;

const string Letters    = "abcdefghijklmnopqrstuvwxyz";
const string BigLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const string TestText   = "Pack my box with five dozen liquor jugs.";
const int Key = 12;

class Encrypting : Enumerator
{
int        _key;
Enumerator _enumerator;

constructor(int key, string text)
{
_key := key;
_enumerator := text.enumerator();
}

bool next() => _enumerator;

reset() => _enumerator;

enumerable() => _enumerator;

get Value()
{
var ch := *_enumerator;

var index := Letters.indexOf(0, ch);

if (-1 < index)
{
^ Letters[(_key+index).mod(26)]
}
else
{
index := BigLetters.indexOf(0, ch);
if (-1 < index)
{
^ BigLetters[(_key+index).mod(26)]
}
else
{
^ ch
}
}
}
}

extension encryptOp
{
encrypt(key)
= new Encrypting(key, self).summarize(new StringWriter());

decrypt(key)
= new Encrypting(26 - key, self).summarize(new StringWriter());
}

public program()
{
console.printLine("Original text :",TestText);

var encryptedText := TestText.encrypt(Key);

console.printLine("Encrypted text:",encryptedText);

var decryptedText := encryptedText.decrypt(Key);

console.printLine("Decrypted text:",decryptedText);

}```
Output:
```Original text :Pack my box with five dozen liquor jugs.
Encrypted text:Bmow yk naj iuft ruhq palqz xucgad vgse.
Decrypted text:Pack my box with five dozen liquor jugs.
```

## Elixir

```defmodule Caesar_cipher do
defp set_map(map, range, key) do
org = Enum.map(range, &List.to_string [&1])
{a, b} = Enum.split(org, key)
Enum.zip(org, b ++ a) |> Enum.into(map)
end

def encode(text, key) do
map = Map.new |> set_map(?a..?z, key) |> set_map(?A..?Z, key)
String.graphemes(text) |> Enum.map_join(fn c -> Map.get(map, c, c) end)
end
end

text = "The five boxing wizards jump quickly"
key = 3
IO.puts "Original:  #{text}"
IO.puts "Encrypted: #{enc = Caesar_cipher.encode(text, key)}"
IO.puts "Decrypted: #{Caesar_cipher.encode(enc, -key)}"
```
Output:
```Original:  The five boxing wizards jump quickly
Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted: The five boxing wizards jump quickly
```

## Elm

```module Main exposing (main)

import Browser
import Html exposing (Html, h2, div, p, input, button, text, textarea)
import Html.Attributes exposing (style, class, placeholder, value)
import Html.Events exposing (onInput, onClick)

-- MAIN

main =
Browser.sandbox { init = init, update = update, view = view }

-- MODEL

type alias Model =
{ codeKey : Int
, normtext : String
}

init : Model
init =
{ codeKey = 3
, normtext = "" }

-- UPDATE

type Msg
= Change String
| DecKey
| IncKey

update : Msg -> Model -> Model
update msg model =
case msg of
DecKey ->
{ model | codeKey = model.codeKey - 1}
IncKey ->
{ model | codeKey = model.codeKey + 1}
Change newContent ->
{ model | normtext = String.toUpper newContent }

encodeChar : Int -> Char -> Char
encodeChar codeKey character =
if Char.isUpper character then
Char.fromCode (modBy 26 (Char.toCode character - 65 + codeKey) + 65)

else if Char.isLower character then
Char.fromCode (modBy 26 (Char.toCode (Char.toUpper character) - 65 + codeKey) + 65)

else
character

encodeText : Int -> String -> String
encodeText codeKey normtext =
String.map (encodeChar codeKey) normtext

if aKey > 0 then "Original"
else if aKey < 0 then "Encrypted text"
else "?"

-- VIEW

view : Model -> Html Msg
view model =
div []
[ div []
[h2 [class "h2style"] [text (subheads model.codeKey)]
, textarea [ class "textframe", placeholder "Write here your text!"
, value model.normtext, onInput Change ] []
]
, div []
[h2 [class "h2style"] [text (subheads (negate model.codeKey))]
, textarea [ class "textframe", value (encodeText model.codeKey model.normtext) ] []]
, div [class "keystyle"] [ button [ class "butstyle", onClick DecKey ] [ text "-1" ]
, text (" Key " ++ String.fromInt model.codeKey)
, button [ class "butstyle", onClick IncKey ] [ text "+1" ]
]
]
```
Output:
```Original:  THE QUICK ORANGE FOX JUMPED OVER THE SLOW DOG
Encrypted: WKH TXLFN RUDQJH IRA MXPSHG RYHU WKH VORZ GRJ (used key value 3)
Encrypted: XLI UYMGO SVERKI JSB NYQTIH SZIV XLI WPSA HSK (used key value 4)
Decrypted: THE QUICK ORANGE FOX JUMPED OVER THE SLOW DOG (used key value -3)
Decrypted: THE QUICK ORANGE FOX JUMPED OVER THE SLOW DOG (used key value -4)

Live version with html file calling the elm module as compiled to JavaScript
at https://ellie-app.com/qVvVDKdK6PQa1
```

## Erlang

```%% Ceasar cypher in Erlang for the rosetta code wiki.
%% Implemented by J.W. Luiten

-module(ceasar).
-export([main/2]).

%% rot: rotate Char by Key places
rot(Char,Key) when (Char >= \$A) and (Char =< \$Z) or
(Char >= \$a) and (Char =< \$z) ->
Offset = \$A + Char band 32,
N = Char - Offset,
Offset + (N + Key) rem 26;
rot(Char, _Key) ->
Char.

%% key: normalize key.
key(Key) when Key < 0 ->
26 + Key rem 26;
key(Key) when Key > 25 ->
Key rem 26;
key(Key) ->
Key.

main(PlainText, Key) ->
Encode = key(Key),
Decode = key(-Key),

io:format("Plaintext ----> ~s~n", [PlainText]),

CypherText = lists:map(fun(Char) -> rot(Char, Encode) end, PlainText),
io:format("Cyphertext ---> ~s~n", [CypherText]),

PlainText = lists:map(fun(Char) -> rot(Char, Decode) end, CypherText).
```

Command:

```ceasar:main("The five boxing wizards jump quickly", 3).
```
Output:
```Plaintext ----> The five boxing wizards jump quickly
Cyphertext ---> Wkh ilyh eralqj zlcdugv mxps txlfnob
"The five boxing wizards jump quickly"
```

## ERRE

```PROGRAM CAESAR

!\$INCLUDE="PC.LIB"

PROCEDURE CAESAR(TEXT\$,KY%->CY\$)
LOCAL I%,C%
FOR I%=1 TO LEN(TEXT\$) DO
C%=ASC(MID\$(TEXT\$,I%))
IF (C% AND \$1F)>=1 AND (C% AND \$1F)<=26 THEN
C%=(C% AND \$E0) OR (((C% AND \$1F)+KY%-1) MOD 26+1)
CHANGE(TEXT\$,I%,CHR\$(C%)->TEXT\$)
END IF
END FOR
CY\$=TEXT\$
END PROCEDURE

BEGIN
RANDOMIZE(TIMER)
PLAINTEXT\$="Pack my box with five dozen liquor jugs"
PRINT(PLAINTEXT\$)

KY%=1+INT(25*RND(1))  ! generates random between 1 and 25
CAESAR(PLAINTEXT\$,KY%->CYPHERTEXT\$)
PRINT(CYPHERTEXT\$)

CAESAR(CYPHERTEXT\$,26-KY%->DECYPHERED\$)
PRINT(DECYPHERED\$)

END PROGRAM```
Output:
```Pack my box with five dozen liquor jugs
Qbdl nz cpy xjui gjwf epafo mjrvps kvht
Pack my box with five dozen liquor jugs
```

## Euphoria

Works with: Euphoria version 4.0.0
```--caesar cipher for Rosetta Code wiki
--User:Lnettnay

--usage eui caesar ->default text, key and encode flag
--usage eui caesar 'Text with spaces and punctuation!' 5 D
--If text has imbedded spaces must use apostophes instead of quotes so all punctuation works
--key = integer from 1 to 25, defaults to 13
--flag = E (Encode) or D (Decode), defaults to E
--no error checking is done on key or flag

include std/get.e
include std/types.e

sequence cmd = command_line()
sequence val
-- default text for encryption
sequence text = "The Quick Brown Fox Jumps Over The Lazy Dog."
atom key = 13 -- default to Rot-13
sequence flag = "E" -- default to Encrypt
atom offset
atom num_letters = 26 -- number of characters in alphabet

--get text
if length(cmd) >= 3 then
text = cmd[3]
end if

--get key value
if length(cmd) >= 4 then
val = value(cmd[4])
key = val[2]
end if

--get Encrypt/Decrypt flag
if length(cmd) = 5 then
flag = cmd[5]
if compare(flag, "D") = 0 then
key = 26 - key
end if
end if

for i = 1 to length(text) do
if t_alpha(text[i]) then
if t_lower(text[i]) then
offset = 'a'
else
offset = 'A'
end if
text[i] = remainder(text[i] - offset + key, num_letters) + offset
end if
end for

printf(1,"%s\n",{text})```
Output:
```"The Quick Brown Fox Jumps Over The Lazy Dog." encrypts to:
"Gur Dhvpx Oebja Sbk Whzcf Bire Gur Ynml Qbt." decrypts to:
"The Quick Brown Fox Jumps Over The Lazy Dog."
```

## F#

```module caesar =
open System

let private cipher n s =
let shift c =
if Char.IsLetter c then
let a = (if Char.IsLower c then 'a' else 'A') |> int
(int c - a + n) % 26 + a |> char
else c
String.map shift s

let encrypt n = cipher n
let decrypt n = cipher (26 - n)
```
```> caesar.encrypt 2 "HI";;
val it : string = "JK"
> caesar.encrypt 20 "HI";;
val it : string = "BC"
> let c = caesar.encrypt 13 "The quick brown fox jumps over the lazy dog.";;
val c : string = "Gur dhvpx oebja sbk whzcf bire gur ynml qbt."
> caesar.decrypt 13 c;;
val it : string = "The quick brown fox jumps over the lazy dog."
```

## Factor

Works with: Factor version 0.97
Translation of: F#
```USING: io kernel locals math sequences unicode.categories ;
IN: rosetta-code.caesar-cipher

:: cipher ( n s -- s' )
[| c |
c Letter? [
c letter? CHAR: a CHAR: A ? :> a
c a - n + 26 mod a +
]
[ c ] if
] :> shift
s [ shift call ] map ;

: encrypt ( n s -- s' ) cipher ;
: decrypt ( n s -- s' ) [ 26 swap - ] dip cipher ;

11 "Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozr." decrypt print
11 "The quick brown fox jumped over the lazy dog." encrypt print
```
Output:
```The quick brown fox jumped over the lazy dog.
Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozr.
```

## Fantom

Shifts upper/lower case letters, leaves other characters as they are.

```class Main
{
static Int shift (Int char, Int key)
{
newChar := char + key
if (char >= 'a' && char <= 'z')
{
if (newChar - 'a' < 0)   { newChar += 26 }
if (newChar - 'a' >= 26) { newChar -= 26 }
}
else if (char >= 'A' && char <= 'Z')
{
if (newChar - 'A' < 0)   { newChar += 26 }
if (newChar - 'A' >= 26) { newChar -= 26 }
}
else // not alphabetic, so keep as is
{
newChar = char
}
return newChar
}

static Str shiftStr (Str msg, Int key)
{
res := StrBuf()
msg.each { res.addChar (shift(it, key)) }
return res.toStr
}

static Str encode (Str msg, Int key)
{
return shiftStr (msg, key)
}

static Str decode (Str msg, Int key)
{
return shiftStr (msg, -key)
}

static Void main (Str[] args)
{
if (args.size == 2)
{
msg := args[0]
key := Int(args[1])

echo ("\$msg with key \$key")
echo ("Encode: \${encode(msg, key)}")
echo ("Decode: \${decode(encode(msg, key), key)}")
}
}
}```

Example:

```\$ fan caesar.fan "Encrypt - With ! Case," 1
Encrypt - With ! Case, with key 1
Encode: Fodszqu - Xjui ! Dbtf,
Decode: Encrypt - With ! Case,

\$ fan caesar.fan "Encrypt - With ! Case," 5
Encrypt - With ! Case, with key 5
Encode: Jshwduy - Bnym ! Hfxj,
Decode: Encrypt - With ! Case,

\$ fan caesar.fan "Encrypt - With ! Case," 10
Encrypt - With ! Case, with key 10
Encode: Oxmbizd - Gsdr ! Mkco,
Decode: Encrypt - With ! Case,
```

## Fhidwfe

only encodes letters

```lowers = ['a','z']
uppers = ['A','Z']
function void caesar_encode(message:ptr key:uint) {
len = strlen\$ message
for uint [0u,len) with index {
temp = deref_ubyte\$ + message index
if in temp lowers {
temp = + temp key// shift lowercase letters
if > temp 'z' {
temp = - temp 26ub
} ;
} {
if in temp uppers {
temp = + temp key// shift uppercase letters
if > temp 'Z' {
temp = - temp 26ub
} ;
} ;//don't shift other characters
}
put_ubyte\$ + message index temp
}
}
function void caesar_decode(message:ptr key:uint) {
caesar_encode\$ message - 26u key
}

key = 1u
response = malloc\$ 256u
puts\$ "plaintext: "
getline\$ response
caesar_encode\$ response key
puts\$ "cyphertext: "
puts\$ response
putln\$
caesar_decode\$ response key
puts\$ "decoded: "
puts\$ response
free\$ response
free\$ lowers // ranges are objects and must be freed
free\$ uppers

//this compiles with only 6 warnings!```

## Forth

```: caesar ( c n -- c )
over 32 or [char] a -
dup 0 26 within if
over + 25 > if 26 - then +
else 2drop then ;

: caesar-string ( n str len -- )
over + swap do i c@ over caesar i c! loop drop ;

: caesar-inverse ( n -- 'n ) 26 swap - 26 mod ;

2variable test
s" The five boxing wizards jump quickly!" test 2!

3 test 2@ caesar-string
test 2@ cr type

3 caesar-inverse test 2@ caesar-string
test 2@ cr type
```

## Fortran

```program Caesar_Cipher
implicit none

integer, parameter :: key = 3
character(43) :: message = "The five boxing wizards jump quickly"

write(*, "(2a)") "Original message  = ", message
call encrypt(message)
write(*, "(2a)") "Encrypted message = ", message
call decrypt(message)
write(*, "(2a)") "Decrypted message = ", message

contains

subroutine encrypt(text)
character(*), intent(inout) :: text
integer :: i

do i = 1, len(text)
select case(text(i:i))
case ('A':'Z')
text(i:i) = achar(modulo(iachar(text(i:i)) - 65 + key, 26) + 65)
case ('a':'z')
text(i:i) = achar(modulo(iachar(text(i:i)) - 97 + key, 26) + 97)
end select
end do
end subroutine

subroutine decrypt(text)
character(*), intent(inout) :: text
integer :: i

do i = 1, len(text)
select case(text(i:i))
case ('A':'Z')
text(i:i) = achar(modulo(iachar(text(i:i)) - 65 - key, 26) + 65)
case ('a':'z')
text(i:i) = achar(modulo(iachar(text(i:i)) - 97 - key, 26) + 97)
end select
end do
end subroutine

end program Caesar_Cipher
```
Output:
```Original message  = The five boxing wizards jump quickly
Encrypted message = Wkh ilyh eralgj zlcdugv mxps txlfnob
Decrypted message = The five boxing wizards jump quickly```

## FreeBASIC

```' FB 1.05.0 Win64

Sub Encrypt(s As String, key As Integer)
Dim c As Integer
For i As Integer = 0 To Len(s)
Select Case As Const s[i]
Case 65 To 90
c = s[i] + key
If c > 90 Then c -= 26
s[i] = c
Case 97 To 122
c = s[i] + key
If c > 122 Then c -= 26
s[i] = c
End Select
Next
End Sub

Sub Decrypt(s As String, key As Integer)
Dim c As Integer
For i As Integer = 0 To Len(s)
Select Case As Const s[i]
Case 65 To 90
c = s[i] - key
If c < 65 Then c += 26
s[i] = c
Case 97 To 122
c = s[i] - key
If c < 97 Then c += 26
s[i] = c
End Select
Next
End Sub

Dim As String s = "Bright vixens jump; dozy fowl quack."
Print "Plain text : "; s
Encrypt s, 8
Print "Encrypted  : "; s
Decrypt s, 8
Print "Decrypted  : "; s
Sleep
```
Output:
```Plain text : Bright vixens jump; dozy fowl quack.
Encrypted  : Jzqopb dqfmva rcux; lwhg nwet yciks.
Decrypted  : Bright vixens jump; dozy fowl quack.
```

## Gambas

```Public Sub Main()
Dim byKey As Byte = 3                                                                 'The key (Enter 26 to get the same output as input)
Dim byCount As Byte                                                                   'Counter
Dim sCeasar As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ"        'Used to calculate the cipher
Dim sString As String = "The five boxing wizards jump quickly"                        'Phrase to encrypt
Dim sCoded, sTemp As String                                                           'Various strings

For byCount = 1 To Len(sString)                                                       'Count through each letter in the phrase
If Mid(sString, byCount, 1) = " " Then                                              'If it's a space..
sCoded &= " "                                                                     'Keep it a space
Endif
sTemp = Mid(sCeasar, InStr(sCeasar, Mid(UCase(sString), byCount, 1)) + byKey, 1)    'Get the new 'coded' letter
If Asc(Mid(sString, byCount, 1)) > 96 Then sTemp = Chr(Asc(sTemp) + 32)             'If the original was lower case then make the new 'coded' letter lower case
sCoded &= sTemp                                                                     'Add the result to the code string
Next

Print sString & gb.NewLine & sCoded                                                   'Print the result

End
```

Output:

```The five boxing wizards jump quickly
Wkh ilyh eralqj zlcdugv mxps txlfnob
```

## GAP

```CaesarCipher := function(s, n)
local r, c, i, lower, upper;
lower := "abcdefghijklmnopqrstuvwxyz";
upper := "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
r := "";
for c in s do
i := Position(lower, c);
if i <> fail then
Add(r, lower[RemInt(i + n - 1, 26) + 1]);
else
i := Position(upper, c);
if i <> fail then
Add(r, upper[RemInt(i + n - 1, 26) + 1]);
else
fi;
fi;
od;
return r;
end;

CaesarCipher("IBM", 25);
# "HAL"

CaesarCipher("Vgg cphvi wzdibn vmz wjmi amzz viy zlpvg di ydbidot viy mdbcon.", 5);
# "All human beings are born free and equal in dignity and rights."
```

## GFA Basic

```'
' Caesar cypher
'
OPENW 1 ! Creates a window for handling input/output
CLEARW 1
INPUT "string to encrypt ";text\$
INPUT "encryption key    ";key%
encrypted\$=@encrypt\$(UPPER\$(text\$),key%)
PRINT "Encrypted: ";encrypted\$
PRINT "Decrypted: ";@decrypt\$(encrypted\$,key%)
'
PRINT "(Press any key to end program.)"
~INP(2)
CLOSEW 1
'
FUNCTION encrypt\$(text\$,key%)
LOCAL result\$,i%,c%
result\$=""
FOR i%=1 TO LEN(text\$)
c%=ASC(MID\$(text\$,i%))
IF c%<ASC("A") OR c%>ASC("Z") ! don't encrypt non A-Z
result\$=result\$+CHR\$(c%)
ELSE
c%=c%+key%
IF c%>ASC("Z")
c%=c%-26
ENDIF
result\$=result\$+CHR\$(c%)
ENDIF
NEXT i%
RETURN result\$
ENDFUNC
'
FUNCTION decrypt\$(text\$,key%)
RETURN @encrypt\$(text\$,26-key%)
ENDFUNC
```

## Go

Obvious solution with explicit testing for character ranges:

```package main

import (
"fmt"
"strings"
)

type ckey struct {
enc, dec func(rune) rune
}

func newCaesar(k int) (*ckey, bool) {
if k < 1 || k > 25 {
return nil, false
}
rk := rune(k)
return &ckey{
enc: func(c rune) rune {
if c >= 'a' && c <= 'z'-rk || c >= 'A' && c <= 'Z'-rk {
return c + rk
} else if c > 'z'-rk && c <= 'z' || c > 'Z'-rk && c <= 'Z' {
return c + rk - 26
}
return c
},
dec: func(c rune) rune {
if c >= 'a'+rk && c <= 'z' || c >= 'A'+rk && c <= 'Z' {
return c - rk
} else if c >= 'a' && c < 'a'+rk || c >= 'A' && c < 'A'+rk {
return c - rk + 26
}
return c
},
}, true
}

func (ck ckey) encipher(pt string) string {
return strings.Map(ck.enc, pt)
}

func (ck ckey) decipher(ct string) string {
return strings.Map(ck.dec, ct)
}

func main() {
pt := "The five boxing wizards jump quickly"
fmt.Println("Plaintext:", pt)
for _, key := range []int{0, 1, 7, 25, 26} {
ck, ok := newCaesar(key)
if !ok {
fmt.Println("Key", key, "invalid")
continue
}
ct := ck.encipher(pt)
fmt.Println("Key", key)
fmt.Println("  Enciphered:", ct)
fmt.Println("  Deciphered:", ck.decipher(ct))
}
}
```

Data driven version using functions designed for case conversion. (And for method using % operator, see Vigenère_cipher#Go.)

```package main

import (
"fmt"
"strings"
"unicode"
)

type ckey struct {
enc, dec unicode.SpecialCase
}

func newCaesar(k int) (*ckey, bool) {
if k < 1 || k > 25 {
return nil, false
}
i := uint32(k)
r := rune(k)
return &ckey{
unicode.SpecialCase{
{'A', 'Z' - i, [3]rune{r}},
{'Z' - i + 1, 'Z', [3]rune{r - 26}},
{'a', 'z' - i, [3]rune{r}},
{'z' - i + 1, 'z', [3]rune{r - 26}},
},
unicode.SpecialCase{
{'A', 'A' + i - 1, [3]rune{26 - r}},
{'A' + i, 'Z', [3]rune{-r}},
{'a', 'a' + i - 1, [3]rune{26 - r}},
{'a' + i, 'z', [3]rune{-r}},
},
}, true
}

func (ck ckey) encipher(pt string) string {
return strings.ToUpperSpecial(ck.enc, pt)
}

func (ck ckey) decipher(ct string) string {
return strings.ToUpperSpecial(ck.dec, ct)
}

func main() {
pt := "The five boxing wizards jump quickly"
fmt.Println("Plaintext:", pt)
for _, key := range []int{0, 1, 7, 25, 26} {
ck, ok := newCaesar(key)
if !ok {
fmt.Println("Key", key, "invalid")
continue
}
ct := ck.encipher(pt)
fmt.Println("Key", key)
fmt.Println("  Enciphered:", ct)
fmt.Println("  Deciphered:", ck.decipher(ct))
}
}
```
Output:

(either version)

```Plaintext: The five boxing wizards jump quickly
Key 0 invalid
Key 1
Enciphered: Uif gjwf cpyjoh xjabset kvnq rvjdlmz
Deciphered: The five boxing wizards jump quickly
Key 7
Enciphered: Aol mpcl ivepun dpghykz qbtw xbpjrsf
Deciphered: The five boxing wizards jump quickly
Key 25
Enciphered: Sgd ehud anwhmf vhyzqcr itlo pthbjkx
Deciphered: The five boxing wizards jump quickly
Key 26 invalid
```

## Groovy

Java style:

```def caesarEncode(​cipherKey, text) {
def builder = new StringBuilder()
text.each { character ->
int ch = character[0] as char
switch(ch) {
case 'a'..'z': ch = ((ch - 97 + cipherKey) % 26 + 97); break
case 'A'..'Z': ch = ((ch - 65 + cipherKey) % 26 + 65); break
}
builder << (ch as char)
}
builder as String
}
def caesarDecode(cipherKey, text) { caesarEncode(26 - cipherKey, text) }
```

Functional style:

```def caesarEncode(cipherKey, text) {
text.chars.collect { c ->
int off = c.isUpperCase() ? 'A' : 'a'
c.isLetter() ? (((c as int) - off + cipherKey) % 26 + off) as char : c
}.join()
}
def caesarDecode(cipherKey, text) { caesarEncode(26 - cipherKey, text) }
```

Ninja style:

```def caesarEncode(k, text) {
(text as int[]).collect { it==' ' ? ' ' : (((it & 0x1f) + k - 1) % 26 + 1 | it & 0xe0) as char }.join()
}
def caesarDecode(k, text) { caesarEncode(26 - k, text) }
```

Using built in 'tr' function and a replacement alphabet:

```def caesarEncode(k, text) {
text.tr('a-zA-Z', ((('a'..'z')*2)[k..(k+25)] + (('A'..'Z')*2)[k..(k+25)]).join())
}
def caesarDecode(cipherKey, text) { caesarEncode(26 - cipherKey, text) }
```

and the same with closures for somewhat better readability:

```def caesarEncode(k, text) {
def c = { (it*2)[k..(k+25)].join() }
text.tr('a-zA-Z', c('a'..'z') + c('A'..'Z'))
}
def caesarDecode(cipherKey, text) { caesarEncode(26 - cipherKey, text) }
```

Test code:

```def plainText = "The Quick Brown Fox jumped over the lazy dog"
def cipherKey = 12
def cipherText = caesarEncode(cipherKey, plainText)
def decodedText = caesarDecode(cipherKey, cipherText)

println "plainText: \$plainText"
println "cypherText(\$cipherKey): \$cipherText"
println "decodedText(\$cipherKey): \$decodedText"

assert  plainText == decodedText
```
Output:
```plainText: The Quick Brown Fox jumped over the lazy dog
cypherText(12): Ftq Cguow Ndaiz Raj vgybqp ahqd ftq xmlk pas
decodedText(12): The Quick Brown Fox jumped over the lazy dog```

```module Caesar (caesar, uncaesar) where

import Data.Char

caesar, uncaesar :: (Integral a) => a -> String -> String
caesar k = map f
where f c = case generalCategory c of
LowercaseLetter -> addChar 'a' k c
UppercaseLetter -> addChar 'A' k c
_               -> c
uncaesar k = caesar (-k)

addChar :: (Integral a) => Char -> a -> Char -> Char
addChar b o c = chr \$ fromIntegral (b' + (c' - b' + o) `mod` 26)
where b' = fromIntegral \$ ord b
c' = fromIntegral \$ ord c
```

And trying it out in GHCi:

```*Main> caesar 1 "hal"
"ibm"
*Main> unCaesar 1 "ibm"
"hal"
```

Similarly, but allowing for negative cipher keys, and using isAlpha, isUpper, negate:

```import Data.Bool (bool)
import Data.Char (chr, isAlpha, isUpper, ord)

---------------------- CAESAR CIPHER ---------------------

caesar, uncaesar :: Int -> String -> String
caesar = fmap . tr
uncaesar = caesar . negate

tr :: Int -> Char -> Char
tr offset c
| isAlpha c =
chr
. ((+) <*> (flip mod 26 . (-) (offset + ord c)))
\$ bool 97 65 (isUpper c)
| otherwise = c

--------------------------- TEST -------------------------
main :: IO ()
main = do
let k = -114
cipher = caesar k
plain = "Curio, Cesare venne, e vide e vinse ? "
mapM_ putStrLn \$ [cipher, uncaesar k . cipher] <*> [plain]
```
Output:
```Skhye, Suiqhu luddu, u lytu u lydiu ?
Curio, Cesare venne, e vide e vinse ? ```

Or with proper error handling:

```{-# LANGUAGE LambdaCase #-}
module Main where

import Data.Char
import System.Exit (die)
import System.Environment (getArgs)

main :: IO ()
main = runExceptT parseKey >>= \case
Left err -> die err
Right k  -> interact \$ caesar k

parseKey :: (Read a, Integral a) => ExceptT String IO a
parseKey = liftIO getArgs >>=
flip (tryAt "Not enough arguments") 0 >>=
tryRead "Key is not a valid integer"

caesar :: (Integral a) => a -> String -> String
caesar k = map f
where f c = case generalCategory c of
LowercaseLetter -> addChar 'a' k c
UppercaseLetter -> addChar 'A' k c
_               -> c

addChar :: (Integral a) => Char -> a -> Char -> Char
addChar b o c = chr \$ fromIntegral (b' + (c' - b' + o) `mod` 26)
where b' = fromIntegral \$ ord b
c' = fromIntegral \$ ord c
```

## Hoon

```|%
++  enc
|=  [msg=tape key=@ud]
^-  tape
(turn `(list @)`msg |=(n=@ud (add (mod (add (sub n 'A') key) 26) 'A')))
++  dec
|=  [msg=tape key=@ud]
(enc msg (sub 26 key))
--```

## Icon and Unicon

Strictly speaking a Ceasar Cipher is a shift of 3 (the default in this case).

```procedure main()
ctext := caesar(ptext := map("The quick brown fox jumped over the lazy dog"))
dtext := caesar(ctext,,"decrypt")
write("Plain text  = ",image(ptext))
write("Encphered text = ",image(ctext))
write("Decphered text = ",image(dtext))
end

procedure caesar(text,k,mode)   #: mono-alphabetic shift cipher
/k := 3
k := (((k % *&lcase) + *&lcase) % *&lcase) + 1
case mode of {
&null|"e"|"encrypt": return map(text,&lcase,(&lcase||&lcase)[k+:*&lcase])
"d"|"decrypt"      : return map(text,(&lcase||&lcase)[k+:*&lcase],&lcase)
}
end
```
Output:
```Plain text  = "the quick brown fox jumped over the lazy dog"
Encphered text = "wkh txlfn eurzq ira mxpshg ryhu wkh odcb grj"
Decphered text = "the quick brown fox jumped over the lazy dog"```

## Insitux

```(function caeser by of
(let alphabets (proj (map char-code) (range 65 91) (range 97 123))
shifted   (.. vec (map (rotate by) alphabets))
table     (kv-dict (flatten alphabets) (flatten shifted)))
(... str (map #(or (table %) %) of)))

(let original "The Quick Brown Fox Jumps Over The Lazy Dog."
encrypted (caeser -1 original)
decrypted (caeser 1 encrypted))
(str "Original:  " original "
Encrypted: " encrypted "
Decrypted: " decrypted)```
Output:
```Original:  The Quick Brown Fox Jumps Over The Lazy Dog.
Encrypted: Sgd Pthbj Aqnvm Enw Itlor Nudq Sgd Kzyx Cnf.
Decrypted: The Quick Brown Fox Jumps Over The Lazy Dog.
```

## IS-BASIC

```100 PROGRAM "CaesarCi.bas"
110 STRING M\$*254
120 INPUT PROMPT "String: ":M\$
130 DO
140   INPUT PROMPT "Key (1-25): ":KEY
150 LOOP UNTIL KEY>0 AND KEY<26
160 PRINT "Original message:  ";M\$
170 CALL ENCRYPT(M\$,KEY)
180 PRINT "Encrypted message: ";M\$
190 CALL DECRYPT(M\$,KEY)
200 PRINT "Decrypted message: ";M\$
210 DEF ENCRYPT(REF M\$,KEY)
220   STRING T\$*254
230   LET T\$=""
240   FOR I=1 TO LEN(M\$)
250     SELECT CASE M\$(I)
260     CASE "A" TO "Z"
270       LET T\$=T\$&CHR\$(65+MOD(ORD(M\$(I))-65+KEY,26))
280     CASE "a" TO "z"
290       LET T\$=T\$&CHR\$(97+MOD(ORD(M\$(I))-97+KEY,26))
300     CASE ELSE
310       LET T\$=T\$&M\$(I)
320     END SELECT
330   NEXT
340   LET M\$=T\$
350 END DEF
360 DEF DECRYPT(REF M\$,KEY)
370   STRING T\$*254
380   LET T\$=""
390   FOR I=1 TO LEN(M\$)
400     SELECT CASE M\$(I)
410     CASE "A" TO "Z"
420       LET T\$=T\$&CHR\$(65+MOD(ORD(M\$(I))-39-KEY,26))
430     CASE "a" TO "z"
440       LET T\$=T\$&CHR\$(97+MOD(ORD(M\$(I))-71-KEY,26))
450     CASE ELSE
460       LET T\$=T\$&M\$(I)
470     END SELECT
480   NEXT
490   LET M\$=T\$
500 END DEF```

## J

If we assume that the task also requires us to leave non-alphabetic characters alone:

```cndx=: [: , 65 97 +/ 26 | (i.26)&+
caesar=: (cndx 0)}&a.@u:@cndx@[ {~ a.i.]
```

Example use:

```   2 caesar 'This simple "monoalphabetic substitution cipher" provides almost no security, ...'
Vjku ukorng "oqpqcnrjcdgvke uwduvkvwvkqp ekrjgt" rtqxkfgu cnoquv pq ugewtkva, ...
```

If we instead assume the task only requires we treat upper case characters:

```CAESAR=:1 :'(26|m&+)&.((26{.64}.a.)&i.)'
```

Example use:

```  20 CAESAR 'HI'
BC
```

## Janet

```(def alphabet "abcdefghijklmnopqrstuvwxyz")

(defn rotate
"shift bytes given x"
[str x]
(let [r (% x (length alphabet))
b (string/bytes str)
abyte (get (string/bytes "a") 0)
zbyte (get (string/bytes "z") 0)]
(var result @[])
(for i 0 (length b)
(let [ch (bor (get b i) 0x20)]  # convert uppercase to lowercase
(when (and (<= abyte ch) (<= ch zbyte))
(array/push result (get alphabet (% (+ (+ (+ (- zbyte abyte) 1) (- ch abyte)) r) (length alphabet)))))))
(string/from-bytes ;result)))

(defn code
"encodes and decodes str given argument type"
[str rot type]
(case type
:encode (rotate str rot)
:decode (rotate str (* rot -1))))

(defn main [& args]
(let [cipher (code "The quick brown fox jumps over the lazy dog" 23 :encode)
str (code cipher 23 :decode)]
(print cipher)
(print str)))```
Output:
```> encode:
"qebnrfzhyoltkclugrjmplsboqebixwvald"
> decode:
"thequickbrownfoxjumpsoverthelazydog"
```

## Java

Works with: Java version 1.5+
```public class Cipher {
public static void main(String[] args) {

String str = "The quick brown fox Jumped over the lazy Dog";

System.out.println( Cipher.encode( str, 12 ));
System.out.println( Cipher.decode( Cipher.encode( str, 12), 12 ));
}

public static String decode(String enc, int offset) {
return encode(enc, 26-offset);
}

public static String encode(String enc, int offset) {
offset = offset % 26 + 26;
StringBuilder encoded = new StringBuilder();
for (char i : enc.toCharArray()) {
if (Character.isLetter(i)) {
if (Character.isUpperCase(i)) {
encoded.append((char) ('A' + (i - 'A' + offset) % 26 ));
} else {
encoded.append((char) ('a' + (i - 'a' + offset) % 26 ));
}
} else {
encoded.append(i);
}
}
return encoded.toString();
}
}
```
Output:
```Ftq cguow ndaiz raj Vgybqp ahqd ftq xmlk Pas
The quick brown fox Jumped over the lazy Dog
```

## JavaScript

### ES5

```function caesar (text, shift) {
return text.toUpperCase().replace(/[^A-Z]/g,'').replace(/./g, function(a) {
return String.fromCharCode(((a.charCodeAt(0) - 65 + shift) % 26 + 26) % 26 + 65);
});
}

// Tests
var text = 'veni, vidi, vici';
for (var i = 0; i<26; i++) {
console.log(i+': '+caesar(text,i));
}
```
Output:
```0: VENIVIDIVICI
1: WFOJWJEJWJDJ
2: XGPKXKFKXKEK
3: YHQLYLGLYLFL
...
```

### ES6

```var caesar = (text, shift) => text
.toUpperCase()
.replace(/[^A-Z]/g, '')
.replace(/./g, a =>
String.fromCharCode(((a.charCodeAt(0) - 65 + shift) % 26 + 26) % 26 + 65));
```

Or, allowing encoding and decoding of both lower and upper case:

```((key, strPlain) => {

// Int -> String -> String
let caesar = (k, s) => s.split('')
.map(c => tr(
inRange(['a', 'z'], c) ? 'a' :
inRange(['A', 'Z'], c) ? 'A' : 0,
k, c
))
.join('');

// Int -> String -> String
let unCaesar = (k, s) => caesar(26 - (k % 26), s);

// Char -> Int -> Char -> Char
let tr = (base, offset, char) =>
base ? (
String.fromCharCode(
ord(base) + (
ord(char) - ord(base) + offset
) % 26
)
) : char;

// [a, a] -> a -> b
let inRange = ([min, max], v) => !(v < min || v > max);

// Char -> Int
let ord = c => c.charCodeAt(0);

// range :: Int -> Int -> [Int]
let range = (m, n) =>
Array.from({
length: Math.floor(n - m) + 1
}, (_, i) => m + i);

// TEST
let strCipher = caesar(key, strPlain),
strDecode = unCaesar(key, strCipher);

return [strCipher, ' -> ', strDecode];

})(114, 'Curio, Cesare venne, e vide e vinse ? ');
```
Output:
`Mebsy, Mockbo foxxo, o fsno o fsxco ? ,  -> , Curio, Cesare venne, e vide e vinse ?`

## jq

Translation of: Wren
Works with: jq

Works with gojq, the Go implementation of jq

```def encrypt(key):
. as \$s
| explode as \$xs
| (key % 26) as \$offset
| if \$offset == 0 then .
else reduce range(0; length) as \$i ( {chars: []};
\$xs[\$i] as \$c
| .d = \$c
| if (\$c >= 65 and \$c <= 90) # 'A' to 'Z'
then .d = \$c + \$offset
| if (.d > 90) then .d += -26 else . end
else if (\$c >= 97 and \$c <= 122) # 'a' to 'z'
then .d = \$c + \$offset
| if (.d > 122)
then .d += -26
else .
end
else .
end
end
| .chars[\$i] = .d )
| .chars | implode
end ;

def decrypt(key): encrypt(26 - key);

"Bright vixens jump; dozy fowl quack."
| .,
(encrypt(8)
| ., decrypt(8) )```
Output:
```Bright vixens jump; dozy fowl quack.
Jzqopb dqfmva rcux; lwhg nwet yciks.
Bright vixens jump; dozy fowl quack.
```

## Jsish

From Typescript entry.

```/* Caesar cipher, in Jsish */
"use strict";

function caesarCipher(input:string, key:number):string {
return input.replace(/([a-z])/g,
function(mat, p1, ofs, str) {
return Util.fromCharCode((p1.charCodeAt(0) + key + 26 - 97) % 26 + 97);
}).replace(/([A-Z])/g,
function(mat, p1, ofs, str) {
return Util.fromCharCode((p1.charCodeAt(0) + key + 26 - 65) % 26 + 65);
});
}

provide('caesarCipher', 1);

if (Interp.conf('unitTest')) {
var str = 'The five boxing wizards jump quickly';
;    str;
;    'Enciphered:';
;    caesarCipher(str, 3);
;    'Enciphered then deciphered';
;    caesarCipher(caesarCipher(str, 3), -3);
}

/*
=!EXPECTSTART!=
str ==> The five boxing wizards jump quickly
'Enciphered:'
caesarCipher(str, 3) ==> Wkh ilyh eralqj zlcdugv mxps txlfnob
'Enciphered then deciphered'
caesarCipher(caesarCipher(str, 3), -3) ==> The five boxing wizards jump quickly
=!EXPECTEND!=
*/
```
Output:
```prompt\$ jsish -u caesarCipher.jsi
[PASS] caesarCipher.jsi```

## Julia

### updated version for Julia 1.x | Rename isalpha to isletter #27077 | https://github.com/JuliaLang/julia/pull/27077

```# Caeser cipher
# Julia 1.5.4
# author: manuelcaeiro | https://github.com/manuelcaeiro

function csrcipher(text, key)
ciphtext = ""
for l in text
numl = Int(l)
ciphnuml = numl + key
if numl in 65:90
if ciphnuml > 90
rotciphnuml = ciphnuml - 26
ciphtext = ciphtext * Char(rotciphnuml)
else
ciphtext = ciphtext * Char(ciphnuml)
end
elseif numl in 97:122
if ciphnuml > 122
rotciphnuml = ciphnuml - 26
ciphtext = ciphtext * Char(rotciphnuml)
else
ciphtext = ciphtext * Char(ciphnuml)
end
else
ciphtext = ciphtext * Char(numl)
end
end
return ciphtext
end

text = "Magic Encryption"; key = 13
csrcipher(text, key)
```
Output:
```"Zntvp Rapelcgvba"
```

## K

Assumes lowercase letters, and no punctuation.

```  s:"there is a tide in the affairs of men"
caesar:{ :[" "=x; x; {x!_ci 97+!26}[y]@_ic[x]-97]}'
caesar[s;1]
"uifsf jt b ujef jo uif bggbjst pg nfo"
```

## Koka

```fun encode(s : string, shift : int)
fun encode-char(c)
if c < 'A' || (c > 'Z' && c < 'a') || c > 'z' return c
val base = if c < 'Z' then (c - 'A').int else (c - 'a').int
val rot  = (base + shift) % 26
(rot.char + (if c < 'Z' then 'A' else 'a'))
s.map(encode-char)

fun decode(s: string, shift: int)
s.encode(0 - shift)

fun trip(s: string, shift: int)
s.encode(shift).decode(shift)

fun main()
"HI".encode(2).println
"HI".encode(20).println
"HI".trip(10).println
val enc = "The quick brown fox jumped over the lazy dog".encode(11)
enc.println
enc.decode(11).println
```
Output:
```JK
BC
HI
Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozr
The quick brown fox jumped over the lazy dog
```

## Kotlin

```// version 1.0.5-2

object Caesar {
fun encrypt(s: String, key: Int): String {
val offset = key % 26
if (offset == 0) return s
var d: Char
val chars = CharArray(s.length)
for ((index, c) in s.withIndex()) {
if (c in 'A'..'Z') {
d = c + offset
if (d > 'Z') d -= 26
}
else if (c in 'a'..'z') {
d = c + offset
if (d > 'z') d -= 26
}
else
d = c
chars[index] = d
}
return chars.joinToString("")
}

fun decrypt(s: String, key: Int): String {
return encrypt(s, 26 - key)
}
}

fun main(args: Array<String>) {
val encoded = Caesar.encrypt("Bright vixens jump; dozy fowl quack.", 8)
println(encoded)
val decoded = Caesar.decrypt(encoded, 8)
println(decoded)
}
```
Output:
```Jzqopb dqfmva rcux; lwhg nwet yciks.
Bright vixens jump; dozy fowl quack.
```

## LabVIEW

For readability, input is in all caps.
This image is a VI Snippet, an executable image of LabVIEW code. The LabVIEW version is shown on the top-right hand corner. You can download it, then drag-and-drop it onto the LabVIEW block diagram from a file browser, and it will appear as runnable, editable code.

## Lambdatalk

The caesar function encodes and decodes texts containing exclusively the set [ABCDEFGHIJKLMNOPQRSTUVWXZ].

```{def caesar

{def caesar.alphabet {A.split ABCDEFGHIJKLMNOPQRSTUVWXYZ}}

{def caesar.delta
{lambda {:s :i :a}
{A.get {% {+ {A.in? {A.get :i :a} {caesar.alphabet}} 26 :s} 26}
{caesar.alphabet}}}}

{def caesar.loop
{lambda {:s :a :b :n :i}
{if {> :i :n}
then :b
else {caesar.r :s
:a
{A.set! :i {caesar.delta :s :i :a} :b}
:n
{+ :i 1}} }}}

{lambda {:shift :txt}
{let { {:s :shift}
{:t {S.replace [^A-Z] by in :txt}} }
{A.join {caesar.loop :s
{A.split :t}
{A.new}
{- {W.length :t} 1}
0 }}}}}
-> caesar

{def text VENI, VIDI, VICI}
-> text
{S.map {lambda {:i} {br}:i: {caesar :i {text}}}
{S.serie 0 26}}
->

0: VENIVIDIVICI
1: WFOJWJEJWJDJ
2: XGPKXKFKXKEK
3: YHQLYLGLYLFL
...
23: SBKFSFAFSFZF
24: TCLGTGBGTGAG
25: UDMHUHCHUHBH
26: VENIVIDIVICI

As a shorter alternative:

{def CAESAR
{def CAESAR.rot
{lambda {:shift :txt :alpha :i}
{A.get {% {+ {A.in? {A.get :i :txt} :alpha} 26 :shift} 26}
:alpha}}}
{def CAESAR.loop
{lambda {:shift :txt :alpha}
{S.map {CAESAR.rot :shift :txt :alpha}
{S.serie 0 {- {A.length :txt} 1}}} }}
{lambda {:shift :txt}
{S.replace \s by in
{CAESAR.loop :shift
{A.split {S.replace \s by in :txt}}
{A.split ABCDEFGHIJKLMNOPQRSTUVWXYZ}} }}}
-> CAESAR

{CAESAR 1 VENI VIDI VICI}
-> WFOJWJEJWJDJ
{CAESAR 25 WFOJWJEJWJDJ}
-> VENIVIDIVICI
```

## langur

Using the built-in rotate() function on a number over a range, a number outside of the range will pass through unaltered.

```val rot = fn(s, key) {
cp2s map(fn(c) { rotate(rotate(c, key, 'a'..'z'), key, 'A'..'Z') }, s2cp(s))
}

val s = "A quick brown fox jumped over something, you know."
val key = 3

writeln " original: ", s
writeln "encrypted: ", rot(s, key)
writeln "decrypted: ", rot(rot(s, key), -key)```
Output:
``` original: A quick brown fox jumped over something.
encrypted: X nrfzh yoltk clu grjmba lsbo pljbqefkd.
decrypted: A quick brown fox jumped over something.```

## Liberty BASIC

```key = 7

Print "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"

'Encrypt the text
Print CaesarCypher\$("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz", key)

'Decrypt the text by changing the key to (26 - key)
Print CaesarCypher\$(CaesarCypher\$("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz", key), (26 - key))

Function CaesarCypher\$(string\$, key)
If (key < 0) Or (key > 25) Then _
CaesarCypher\$ = "Key is Ouside of Bounds" : Exit Function
For i = 1 To Len(string\$)
rotate = Asc(Mid\$(string\$, i, 1))
rotate = (rotate + key)
If Asc(Mid\$(string\$, i, 1)) > Asc("Z") Then
If rotate > Asc("z") Then rotate = (Asc("a") + (rotate - Asc("z")) - 1)
Else
If rotate > Asc("Z") Then rotate = (Asc("A") + (rotate - Asc("Z")) - 1)
End If
CaesarCypher\$ = (CaesarCypher\$ + Chr\$(rotate))
Next i
End Function```

## LiveCode

```function caesarCipher rot phrase
local rotPhrase, lowerLetters, upperLetters
put "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz" into lowerLetters
put "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ" into upperLetters
repeat for each char letter in phrase
get charTonum(letter)
if it >= 65 and it <= 90 then
put char ((it + rot) - 64) of upperLetters after rotPhrase
else if it >= 97 and it <= 122 then
put char ((it + rot) - 96) of lowerLetters after rotPhrase
else
put letter after rotPhrase
end if
end repeat
return rotPhrase
end caesarCipher```

## Logo

Translation of: Common Lisp
Works with: UCB Logo
```; some useful constants
make "lower_a ascii "a
make "lower_z ascii "z
make "upper_a ascii "A
make "upper_z ascii "Z

; encipher a single character
to encipher_char :char :key
local "code make "code ascii :char
local "base make "base 0
ifelse [and (:code >= :lower_a) (:code <= :lower_z)] [make "base :lower_a] [
if [and (:code >= :upper_a) (:code <= :upper_z)] [make "base :upper_a] ]
ifelse [:base > 0] [
output char (:base + (modulo ( :code - :base + :key ) 26 ))
] [
output :char
]
end

; encipher a whole string
to caesar_cipher :string :key
output map [encipher_char ? :key] :string
end

; Demo
make "plaintext "|The five boxing wizards jump quickly|
make "key 3
make "ciphertext caesar_cipher :plaintext :key
make "recovered  caesar_cipher :ciphertext -:key

print sentence "| Original:| :plaintext
print sentence "|Encrypted:| :ciphertext
print sentence "|Recovered:| :recovered
bye```
Output:
``` Original: The five boxing wizards jump quickly
Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob
Recovered: The five boxing wizards jump quickly```

## Lua

```local function encrypt(text, key)
return text:gsub("%a", function(t)
local base = (t:lower() == t and string.byte('a') or string.byte('A'))

local r = t:byte() - base
r = r + key
r = r%26 -- works correctly even if r is negative
r = r + base
return string.char(r)
end)
end

local function decrypt(text, key)
return encrypt(text, -key)
end

caesar = {
encrypt = encrypt,
decrypt = decrypt,
}

-- test
do
local text = "ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz"
local encrypted = caesar.encrypt(text, 7)
local decrypted = caesar.decrypt(encrypted, 7)
print("Original text:  ", text)
print("Encrypted text: ", encrypted)
print("Decrypted text: ", decrypted)
end
```

Fast version

```local memo = {}

local function make_table(k)
local t = {}
local a, A = ('a'):byte(), ('A'):byte()

for i = 0,25 do
local  c = a + i
local  C = A + i
local rc = a + (i+k) % 26
local RC = A + (i+k) % 26
t[c], t[C] = rc, RC
end

return t
end

local function caesar(str, k, decode)
k = (decode and -k or k) % 26

local t = memo[k]
if not t then
t = make_table(k)
memo[k] = t
end

local res_t = { str:byte(1,-1) }
for i,c in ipairs(res_t) do
res_t[i] = t[c] or c
end
return string.char(unpack(res_t))
end
```

## M2000 Interpreter

We use a Buffer object (is a pointer type to a block of memory), to store string, to have access using unsigned integers.

```a\$="THIS IS MY TEXT TO ENCODE WITH CAESAR CIPHER"
Function Cipher\$(a\$, N) {
If Len(a\$)=0 Then Exit
a\$=Ucase\$(a\$)
\\ Integer in Mem is unsigned number
Buffer Mem as Integer*Len(a\$)
Return Mem, 0:=a\$
For i=0 to Len(a\$)-1 {
If Eval(mem, i)>=65 and Eval(mem, i)<=90 then Return Mem, i:=(Eval(mem, i)-39+n) mod 26 + 65
}
=Eval\$(Mem)
}
B\$=Cipher\$(a\$, 10)
Print B\$
Print Cipher\$(B\$,-10)

n=1 ' n negative or positive or zero
for i=65 to 65+25
a=(1+(i -64)+n+24) mod 26 + 65
? chr\$(a),
next```

?

## Maple

```> StringTools:-Encode( "The five boxing wizards jump quickly", encoding = alpharot[3] );
"Wkh ilyh eralqj zlcdugv mxps txlfnob"

> StringTools:-Encode( %, encoding = alpharot[ 23 ] );
"The five boxing wizards jump quickly"```

(The symbol % refers the the last (non-NULL) value computed.)

## Mathematica / Wolfram Language

```cypher[mesg_String,n_Integer]:=StringReplace[mesg,Flatten[Thread[Rule[#,RotateLeft[#,n]]]&/@CharacterRange@@@{{"a","z"},{"A","Z"}}]]
```
Output:
```cypher["The five boxing wizards jump quickly",3]
-> Wkh ilyh eralqj zlcdugv mxps txlfnob```

## MATLAB / Octave

```   function s = cipherCaesar(s, key)
s = char( mod(s - 'A' + key, 25 ) + 'A');
end;
function s = decipherCaesar(s, key)
s = char( mod(s - 'A' - key, 25 ) + 'A');
end;
```

Here is a test:

```   decipherCaesar(cipherCaesar('ABC',4),4)
ans = ABC
```

## Microsoft Small Basic

```TextWindow.Write("Enter a 1-25 number key (-ve number to decode): ")
TextWindow.Write("Enter message: ")
caeser = ""
For n = 1 To Text.GetLength(message)
letter = Text.GetSubText(message,n,1)
code = Text.GetCharacterCode(letter)
If code = 32 Then
newCode = 32
Else
newCode = code + key
If newCode > 90 Then
newCode = newCode - 26
ElseIf newCode < 65 then
newCode = newCode + 26
EndIf
EndIf
codeLetter = Text.GetCharacter(newCode)
caeser = Text.Append(caeser,codeLetter)
EndFor
TextWindow.WriteLine(message)
TextWindow.WriteLine(caeser)```
Output:
```Enter a 1-25 number key (-ve number to decode): 10
Enter message: HAVE A NICE DAY
HAVE A NICE DAY
RKFO K XSMO NKI
Press any key to continue...

Enter a 1-25 number key (-ve number to decode): -10
Enter message: RKFO K XSMO NKI
RKFO K XSMO NKI
HAVE A NICE DAY
Press any key to continue...
```

## MiniScript

```caesar = function(s, key)
chars = s.values
for i in chars.indexes
c = chars[i]
if c >= "a" and c <= "z" then chars[i] = char(97 + (code(c)-97+key)%26)
if c >= "A" and c <= "Z" then chars[i] = char(65 + (code(c)-65+key)%26)
end for
return chars.join("")
end function

print caesar("Hello world!", 7)
print caesar("Olssv dvysk!", 26-7)
```
Output:
```Olssv dvysk!
Hello world!```

## ML

### mLite

In this implementation, the offset can be positive or negative and is wrapped around if greater than 25 or less than -25.

```fun readfile () = readfile []
| x = let val ln = readln ()
in if eof ln then
rev x
else
end

local
val lower_a = ord #"a";
val lower_z = ord #"z";
val upper_a = ord #"A";
val upper_z = ord #"Z";

fun which
(c_upper c) = (upper_a, upper_z)
|	_	    = (lower_a, lower_z)
;

fun scale
(c, az) where (c > #1 az) = scale( (#0 az + (c - #1 az - 1)), az)
|	(c, az) 		  = c

in
fun encipher
([], offset, t)                             = implode ` rev t
|	(x :: xs, offset, t) where (c_alphabetic x) = encipher (xs, offset, (chr ` scale (ord x + offset, which x)) :: t)
|	(x :: xs, offset, t)                        = encipher (xs, offset, x :: t)
|	(s, offset) 				    = if (offset < 0) then
encipher (explode s, 26 + (offset rem 26), [])
else
encipher (explode s, offset rem 26, [])
end

fun default
(false, y) = y
|	(x,     _) = x

;
map println ` map (fn s = encipher (s,ston ` default (argv 0, "1"))) ` readfile ();
```

The string for encoding is supplied as an input stream, and the offset supplied on the command line (defaults to 1). For example

`echo The cat sat on the mat | mlite -f caecip.m ~5`

Output:

`Ocz xvo nvo ji ocz hvo`

## Modula-2

Translation of: Java
```MODULE CaesarCipher;
FROM Conversions IMPORT IntToStr;
FROM Terminal IMPORT WriteString, WriteLn, ReadChar;

TYPE String = ARRAY[0..64] OF CHAR;

PROCEDURE Encrypt(p : String; key : CARDINAL) : String;
VAR e : String;
VAR i,t : CARDINAL;
VAR c : CHAR;
BEGIN
FOR i:=0 TO HIGH(p) DO
IF p[i]=0C THEN BREAK; END;

t := ORD(p[i]);
IF (p[i]>='A') AND (p[i]<='Z') THEN
t := t + key;
IF t>ORD('Z') THEN
t := t - 26;
END;
ELSIF (p[i]>='a') AND (p[i]<='z') THEN
t := t + key;
IF t>ORD('z') THEN
t := t - 26;
END;
END;
e[i] := CHR(t);
END;
RETURN e;
END Encrypt;

PROCEDURE Decrypt(p : String; key : CARDINAL) : String;
VAR e : String;
VAR i,t : CARDINAL;
VAR c : CHAR;
BEGIN
FOR i:=0 TO HIGH(p) DO
IF p[i]=0C THEN BREAK; END;

t := ORD(p[i]);
IF (p[i]>='A') AND (p[i]<='Z') THEN
t := t - key;
IF t<ORD('A') THEN
t := t + 26;
END;
ELSIF (p[i]>='a') AND (p[i]<='z') THEN
t := t - key;
IF t<ORD('a') THEN
t := t + 26;
END;
END;
e[i] := CHR(t);
END;
RETURN e;
END Decrypt;

VAR txt,enc : String;
VAR key : CARDINAL;
BEGIN
txt := "The five boxing wizards jump quickly";
key := 3;

WriteString("Original:  ");
WriteString(txt);
WriteLn;

enc := Encrypt(txt, key);
WriteString("Encrypted: ");
WriteString(enc);
WriteLn;

WriteString("Decrypted: ");
WriteString(Decrypt(enc, key));
WriteLn;

END CaesarCipher.
```

## Modula-3

This implementation distinguishes between "encoding" and "encryption." The former turns letters into numbers; the latter turns numbers into different ("cryptic") numbers. The distinction between "decoding" and "decryption" is similar. It also illustrates the use of exceptions in Modula-3.

```MODULE Caesar EXPORTS Main;

IMPORT IO, IntSeq, Text;

(* Used whenever message contains a non-alphabetic character. *)

(*
Converts upper or lower case letter to 0..25.
Raises a "BadCharacter" exception for non-alphabetic characters.
*)
VAR
c: CHAR;
v: INTEGER;
BEGIN
FOR i := 0 TO Text.Length(message) - 1 DO
c := Text.GetChar(message, i);
CASE c OF
| 'A'..'Z' => v := ORD(c) - ORD('A');
| 'a'..'z' => v := ORD(c) - ORD('a');
ELSE
END;
END;
END Encode;

PROCEDURE Decode(READONLY numbers: IntSeq.T; VAR message: TEXT) =
(* converts numbers in 0..26 to lower case characters *)
BEGIN
FOR i := 0 TO numbers.size() - 1 DO
message := message & Text.FromChar(VAL(numbers.get(i) + ORD('a'), CHAR));
END;
END Decode;

PROCEDURE Crypt(numbers: IntSeq.T; key: INTEGER) =
(*
In the Caesar cipher, encryption and decryption are really the same;
one adds the key, the other subtracts it. We can view this as adding a positive
or nevative integer; the common task is adding an integer. We call this "Crypt".
*)
BEGIN
FOR i := 0 TO numbers.size() - 1 DO
numbers.put(i, (numbers.get(i) + key) MOD 26);
END;
END Crypt;

PROCEDURE Encrypt(numbers: IntSeq.T; key := 4) =
(*
Encrypts a message of numbers using the designated key.
The result is also stored in "numbers".
*)
BEGIN
Crypt(numbers, key);
END Encrypt;

PROCEDURE Decrypt(numbers: IntSeq.T; key := 4) =
(*
Decrypts a message of numbers using the designated key.
The result is also stored in "numbers".
*)
BEGIN
Crypt(numbers, -key);
END Decrypt;

VAR

message := "";
buffer := NEW(IntSeq.T).init(22); (* sequence of 22 int's *)

BEGIN
TRY
Encode("WhenCaesarSetOffToGaul", buffer);
(*
This should never occur.
Try adding spaces to the above to see what happens.
*)
END;
Encrypt(buffer);
Decrypt(buffer);
Decode(buffer, message);
IO.Put(message); IO.PutChar('\n');
END Caesar.
```
Output:

Notice the output comes out all lower-case.

```whencaesarsetofftogaul
```

## Nanoquery

```def caesar_encode(plaintext, shift)
uppercase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
lowercase = "abcdefghijklmnopqrstuvwxyz"

cipher = ""
for char in plaintext
if char in uppercase
cipher += uppercase[uppercase[char] - (26 - shift)]
else if char in lowercase
cipher += lowercase[lowercase[char] - (26 - shift)]
else
cipher += char
end
end

return cipher
end

def caesar_decode(cipher, shift)
uppercase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
lowercase = "abcdefghijklmnopqrstuvwxyz"

plaintext = ""
for char in cipher
if char in uppercase
plaintext += uppercase[uppercase[char] - shift]
else if char in lowercase
plaintext += lowercase[lowercase[char] - shift]
else
plaintext += char
end
end

return plaintext
end```

## NetRexx

The cipher code in this sample is also used in the Rot-13 – NetRexx task.

```/* NetRexx */

options replace format comments java crossref savelog symbols nobinary

messages = [ -
'The five boxing wizards jump quickly', -
'Attack at dawn!', -
'HI']
keys = [1, 2, 20, 25, 13]

loop m_ = 0 to messages.length - 1
in = messages[m_]
loop k_ = 0 to keys.length - 1
say 'Caesar cipher, key:' keys[k_].right(3)
ec = caesar_encipher(in, keys[k_])
dc = caesar_decipher(ec, keys[k_])
say in
say ec
say dc
say
end k_
say 'Rot-13:'
ec = rot13(in)
dc = rot13(ec)
say in
say ec
say dc
say
end m_

return

method rot13(input) public static signals IllegalArgumentException

return caesar(input, 13, isFalse)

method caesar(input = Rexx, idx = int, caps = boolean) public static signals IllegalArgumentException

if idx < 1 | idx > 25 then signal IllegalArgumentException()

--      12345678901234567890123456
itab = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
shift = itab.length - idx
parse itab tl +(shift) tr
otab = tr || tl

if caps then input = input.upper

cipher = input.translate(itab || itab.lower, otab || otab.lower)

return cipher

method caesar_encipher(input = Rexx, idx = int, caps = boolean) public static signals IllegalArgumentException

return caesar(input, idx, caps)

method caesar_decipher(input = Rexx, idx = int, caps = boolean) public static signals IllegalArgumentException

return caesar(input, int(26) - idx, isFalse)

method caesar_encipher(input = Rexx, idx = int) public static signals IllegalArgumentException

return caesar(input, idx, isFalse)

method caesar_decipher(input = Rexx, idx = int) public static signals IllegalArgumentException

return caesar(input, int(26) - idx, isFalse)

method caesar_encipher(input = Rexx, idx = int, opt = Rexx) public static signals IllegalArgumentException

return caesar(input, idx, opt)

method caesar_decipher(input = Rexx, idx = int, opt = Rexx) public static signals IllegalArgumentException

return caesar(input, int(26) - idx, opt)

method caesar(input = Rexx, idx = int, opt = Rexx) public static signals IllegalArgumentException

if opt.upper.abbrev('U') >= 1 then caps = isTrue
else                               caps = isFalse

return caesar(input, idx, caps)

method caesar(input = Rexx, idx = int) public static signals IllegalArgumentException

return caesar(input, idx, isFalse)

method isTrue public static returns boolean
return (1 == 1)

method isFalse public static returns boolean
return \isTrue
```
```Caesar cipher, key:   1
The five boxing wizards jump quickly
Uif gjwf cpyjoh xjabset kvnq rvjdlmz
The five boxing wizards jump quickly

Caesar cipher, key:   2
The five boxing wizards jump quickly
Vjg hkxg dqzkpi ykbctfu lwor swkemna
The five boxing wizards jump quickly

Caesar cipher, key:  20
The five boxing wizards jump quickly
Nby zcpy vircha qctulxm dogj kocwefs
The five boxing wizards jump quickly

Caesar cipher, key:  25
The five boxing wizards jump quickly
Sgd ehud anwhmf vhyzqcr itlo pthbjkx
The five boxing wizards jump quickly

Caesar cipher, key:  13
The five boxing wizards jump quickly
Gur svir obkvat jvmneqf whzc dhvpxyl
The five boxing wizards jump quickly

Rot-13:
The five boxing wizards jump quickly
Gur svir obkvat jvmneqf whzc dhvpxyl
The five boxing wizards jump quickly

Caesar cipher, key:   1
Attack at dawn!
Buubdl bu ebxo!
Attack at dawn!

Caesar cipher, key:   2
Attack at dawn!
Cvvcem cv fcyp!
Attack at dawn!

Caesar cipher, key:  20
Attack at dawn!
Unnuwe un xuqh!
Attack at dawn!

Caesar cipher, key:  25
Attack at dawn!
Zsszbj zs czvm!
Attack at dawn!

Caesar cipher, key:  13
Attack at dawn!
Nggnpx ng qnja!
Attack at dawn!

Rot-13:
Attack at dawn!
Nggnpx ng qnja!
Attack at dawn!

Caesar cipher, key:   1
HI
IJ
HI

Caesar cipher, key:   2
HI
JK
HI

Caesar cipher, key:  20
HI
BC
HI

Caesar cipher, key:  25
HI
GH
HI

Caesar cipher, key:  13
HI
UV
HI

Rot-13:
HI
UV
HI
```

## Nim

Translation of: Python
```import strutils

proc caesar(s: string, k: int, decode = false): string =
var k = if decode: 26 - k else: k
result = ""
for i in toUpper(s):
if ord(i) >= 65 and ord(i) <= 90:
result.add(chr((ord(i) - 65 + k) mod 26 + 65))

let msg = "The quick brown fox jumped over the lazy dogs"
echo msg
let enc = caesar(msg, 11)
echo enc
echo caesar(enc, 11, decode = true)
```

## Oberon-2

Works with oo2c version2

```MODULE Caesar;
IMPORT
Out;
CONST
encode* = 1;
decode* = -1;

VAR
text,cipher: POINTER TO ARRAY OF CHAR;

PROCEDURE Cipher*(txt: ARRAY OF CHAR; key: INTEGER; op: INTEGER; VAR cipher: ARRAY OF CHAR);
VAR
i: LONGINT;
BEGIN
i := 0;
WHILE i < LEN(txt) - 1 DO
IF (txt[i] >= 'A') & (txt[i] <= 'Z') THEN
cipher[i] := CHR(ORD('A') + ((ORD(txt[i]) - ORD('A') + (key * op))) MOD 26)
ELSIF (txt[i] >= 'a') & (txt[i] <= 'z') THEN
cipher[i] := CHR(ORD('a') + ((ORD(txt[i]) - ORD('a') + (key * op))) MOD 26)
ELSE
cipher[i] := txt[i]
END;
INC(i)
END;
cipher[i] := 0X
END Cipher;

BEGIN
NEW(text,3);NEW(cipher,3);
COPY("HI",text^);
Out.String(text^);Out.String(" =e=> ");
Cipher(text^,2,encode,cipher^);
Out.String(cipher^);

COPY(cipher^,text^);
Cipher(text^,2,decode,cipher^);
Out.String(" =d=> ");Out.String(cipher^);Out.Ln;

COPY("ZA",text^);
Out.String(text^);Out.String(" =e=> ");
Cipher(text^,2,encode,cipher^);
Out.String(cipher^);

COPY(cipher^,text^);
Cipher(text^,2,decode,cipher^);
Out.String(" =d=> ");Out.String(cipher^);Out.Ln;

NEW(text,37);NEW(cipher,37);
COPY("The five boxing wizards jump quickly",text^);
Out.String(text^);Out.String(" =e=> ");
Cipher(text^,3,encode,cipher^);
Out.String(cipher^);

COPY(cipher^,text^);
Cipher(text^,3,decode,cipher^);
Out.String(" =d=> ");Out.String(cipher^);Out.Ln;

END Caesar.
```

Output:

```HI =e=> JK =d=> HI
ZA =e=> BC =d=> ZA
The five boxing wizards jump quickly =e=> Wkh ilyh eralqj zlcdugv mxps txlfnob =d=> The five boxing wizards jump quickly
```

## Objeck

```class Caesar {
function : native : Encode(enc : String, offset : Int) ~ String {
offset := offset % 26 + 26;
encoded := "";
enc := enc->ToLower();
each(i : enc) {
c := enc->Get(i);
if(c->IsChar()) {
j := (c - 'a' + offset) % 26;
encoded->Append(j + 'a');
}
else {
encoded->Append(c);
};
};

return encoded;
}

function : Decode(enc : String, offset : Int) ~ String {
return Encode(enc, offset * -1);
}

function : Main(args : String[]) ~ Nil {
enc := Encode("The quick brown fox Jumped over the lazy Dog", 12);
enc->PrintLine();
Decode(enc, 12)->PrintLine();
}
}```
Output:
```ftq cguow ndaiz raj vgybqp ahqd ftq xmlk pas
the quick brown fox jumped over the lazy dog
```

## OCaml

```let islower c =
c >= 'a' && c <= 'z'

let isupper c =
c >= 'A' && c <= 'Z'

let rot x str =
let upchars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
and lowchars = "abcdefghijklmnopqrstuvwxyz" in
let rec decal x =
if x < 0 then decal (x + 26) else x
in
let x = (decal x) mod 26 in
let decal_up = x - (int_of_char 'A')
and decal_low = x - (int_of_char 'a') in
String.map (fun c ->
if islower c then
let j = ((int_of_char c) + decal_low) mod 26 in
lowchars.[j]
else if isupper c then
let j = ((int_of_char c) + decal_up) mod 26 in
upchars.[j]
else
c
) str
```
```let () =
let key = 3 in
let orig = "The five boxing wizards jump quickly" in
let enciphered = rot key orig in
print_endline enciphered;
let deciphered = rot (- key) enciphered in
print_endline deciphered;
Printf.printf "equal: %b\n" (orig = deciphered)
;;
```
Output:
```\$ ocaml caesar.ml
Wkh ilyh eralqj zlcdugv mxps txlfnob
The five boxing wizards jump quickly
equal: true```

## Oforth

```: ceasar(c, key)
c dup isLetter ifFalse: [ return ]
isUpper ifTrue: [ 'A' ] else: [ 'a' ] c key + over - 26 mod + ;

: cipherE(s, key)  s map(#[ key ceasar ]) charsAsString ;
: cipherD(s, key)  cipherE(s, 26 key - ) ;```
Output:
```>cipherE("Pack my box with five dozen liquor jugs.", 5) println
Ufhp rd gtc bnym knaj itejs qnvztw ozlx.
ok
>cipherD("Ufhp rd gtc bnym knaj itejs qnvztw ozlx.", 5) println
Pack my box with five dozen liquor jugs.
```

## OmniMark

```; caesar.xom
global integer gi-k initial {13}
global stream gs-ed initial {'encode'}
global stream gs-phrase

define stream function apply-cipher (value stream phrase, value integer k, value stream ed) as
local integer b
local stream ciphered
open ciphered as buffer
repeat scan phrase
match letter => char
set b to char binary 0
increment b by k when ed = 'encode'
increment b by 26 - k when ed = 'decode'
decrement b by 26 when char matches uc and b > 90
decrement b by 26 when char matches lc and b > 122
put ciphered "b" % b
match any => char
put ciphered char
again
close ciphered
return ciphered

process
output apply-cipher(gs-phrase, gi-k, gs-ed) || '%n%n'```
Output:
```> omnimark -sb caesar.xom -c gi-k 2 -d gs-ed encode -d gs-phrase 'HI! The quick brown fox jumps over the lazy dog.'
JK! Vjg swkem dtqyp hqz lworu qxgt vjg ncba fqi.

> omnimark -sb caesar.xom -c gi-k 20 -d gs-ed encode -d gs-phrase 'HI! The quick brown fox jumps over the lazy dog.'
BC! Nby kocwe vliqh zir dogjm ipyl nby futs xia.

> omnimark -sb caesar.xom -c gi-k 2 -d gs-ed decode -d gs-phrase 'JK! Vjg swkem dtqyp hqz lworu qxgt vjg ncba fqi.'
HI! The quick brown fox jumps over the lazy dog.

> omnimark -sb caesar.xom -c gi-k 20 -d gs-ed decode -d gs-phrase 'BC! Nby kocwe vliqh zir dogjm ipyl nby futs xia.'
HI! The quick brown fox jumps over the lazy dog.
```

## OOC

```main: func (args: String[]) {
shift := args[1] toInt()
if (args length != 3) {
"Usage: #{args[0]} [number] [sentence]" println()
"Incorrect number of arguments." println()
} else if (!shift && args[1] != "0"){
"Usage: #{args[0]} [number] [sentence]" println()
"Number is not a valid number." println()
} else {
str := ""
for (c in args[2]) {
if (c alpha?()) {
c = (c lower?() ? 'a' : 'A') + (26 + c toLower() - 'a' + shift) % 26
}
str += c
}
str println()
}
}
```
Output:
```\$ ./caesar 8 "This should be a fairly original sentence."
Bpqa apwctl jm i niqztg wzqoqvit amvbmvkm.
\$ ./caesar -9 "Yet another, fairly original sentence!"
Pvk refkyvi, wrzicp fizxzerc jvekvetv!```

## PARI/GP

```enc(s,n)={
Strchr(Vecsmall(apply(k->if(k>96&&k<123,(k+n-97)%26+97, if(k>64&&k<91, (k+n-65)%26+65, k)),
Vec(Vecsmall(s)))))
};
dec(s,n)=enc(s,-n);```

## Pascal

```Program CaesarCipher(output);

procedure encrypt(var message: string; key: integer);
var
i: integer;
begin
for i := 1 to length(message) do
case message[i] of
'A'..'Z': message[i] := chr(ord('A') + (ord(message[i]) - ord('A') + key) mod 26);
'a'..'z': message[i] := chr(ord('a') + (ord(message[i]) - ord('a') + key) mod 26);
end;
end;

procedure decrypt(var message: string; key: integer);
var
i: integer;
begin
for i := 1 to length(message) do
case message[i] of
'A'..'Z': message[i] := chr(ord('A') + (ord(message[i]) - ord('A') - key + 26) mod 26);
'a'..'z': message[i] := chr(ord('a') + (ord(message[i]) - ord('a') - key + 26) mod 26);
end;
end;

var
key: integer;
message: string;

begin
key := 3;
message := 'The five boxing wizards jump quickly';
writeln ('Original message: ', message);
encrypt(message, key);
writeln ('Encrypted message: ', message);
decrypt(message, key);
writeln ('Decrypted message: ', message);
end.
```
Output:
```>: ./CaesarCipher
Original message: The five boxing wizards jump quickly
Encrypted message: Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted message: The five boxing wizards jump quickly
>: ```

## PascalABC.NET

```##
function encrypt(msg:string;k:integer):string;
begin
var big:=('A'..'Z').ToArray;
var ltl:=('a'..'z').ToArray;
foreach var c in msg do
case c of
'A'..'Z': result+=big[(big.IndexOf(c)+k) mod 26];
'a'..'z': result+=ltl[(ltl.IndexOf(c)+k) mod 26];
else result+=c;
end;
end;
function decrypt(msg:string;k:integer):=encrypt(msg, 26-k);

var (key, message):=(3,'The five boxing wizards jump quickly');
Println('Original:',message);
message:=encrypt(message, 3);
Println('Encrypted:',message);
message:=decrypt(message, 3);
Println('Decrypted:',message);
```
Output:
```Original: The five boxing wizards jump quickly
Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted: The five boxing wizards jump quickly```

## Perl

```sub caesar {
my (\$message, \$key, \$decode) = @_;
\$key = 26 - \$key if \$decode;
\$message =~ s/([A-Z])/chr(((ord(uc \$1) - 65 + \$key) % 26) + 65)/geir;
}

my \$msg = 'THE FIVE BOXING WIZARDS JUMP QUICKLY';
my \$enc = caesar(\$msg, 10);
my \$dec = caesar(\$enc, 10, 'decode');

print "msg: \$msg\nenc: \$enc\ndec: \$dec\n";```
Output:
```msg: THE FIVE BOXING WIZARDS JUMP QUICKLY
enc: DRO PSFO LYHSXQ GSJKBNC TEWZ AESMUVI
dec: THE FIVE BOXING WIZARDS JUMP QUICKLY```

## Phix

```with javascript_semantics
sequence alpha_b = repeat(0,255)
alpha_b['A'..'Z'] = 'A'
alpha_b['a'..'z'] = 'a'

function caesar(string s, integer key)
integer ch, base
for i=1 to length(s) do
ch = s[i]
base = alpha_b[ch]
if base then
s[i] = base+remainder(ch-base+key,26)
end if
end for
return s
end function
string s = "One fine day in the middle of the night, two dead men got up to fight. \n"&
"Back to back they faced each other, drew their swords and shot each other. %^&*()[",
e = caesar(s,5),
r = caesar(e,26-5)  ?e ?r
```
Output:
```Tsj knsj ifd ns ymj rniiqj tk ymj snlmy, ybt ijfi rjs lty zu yt knlmy.
Gfhp yt gfhp ymjd kfhji jfhm tymjw, iwjb ymjnw xbtwix fsi xmty jfhm tymjw. %^&*()[
One fine day in the middle of the night, two dead men got up to fight.
Back to back they faced each other, drew their swords and shot each other. %^&*()[
```

## PHP

```<?php
function caesarEncode( \$message, \$key ){
\$plaintext = strtolower( \$message );
\$ciphertext = "";
\$ascii_a = ord( 'a' );
\$ascii_z = ord( 'z' );
while( strlen( \$plaintext ) ){
\$char = ord( \$plaintext );
if( \$char >= \$ascii_a && \$char <= \$ascii_z ){
\$char = ( ( \$key + \$char - \$ascii_a ) % 26 ) + \$ascii_a;
}
\$plaintext = substr( \$plaintext, 1 );
\$ciphertext .= chr( \$char );
}
return \$ciphertext;
}

echo caesarEncode( "The quick brown fox Jumped over the lazy Dog", 12 ), "\n";
?>```
Output:
`ftq cguow ndaiz raj vgybqp ahqd ftq xmlk pas`

Or, using PHP's strtr() built-in function

```<?php

function caesarEncode(\$message, \$key) {
\$from = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
\$to   = substr(\$from, \$key) . substr(\$from, 0, \$key);
return strtr(\$message, \$from, \$to);
}

echo caesarEncode('THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG', 12), PHP_EOL;```
Output:
`FTQ CGUOW NDAIZ RAJ VGYBQP AHQD FTQ XMLK PAS`

## Picat

```main =>
S = "All human beings are born free and equal in dignity and rights.",
println(S),
println(caesar(S,5)),
println(caesar(caesar(S,5),-5)),
nl.

caesar(String, N) = Cipher =>
Lower = [chr(I): I in 97..122],
Upper = [chr(I): I in 65..90],
M = create_map(Lower, Upper, N),
% If a char is not in a..zA..z then show it as it is.
Cipher := [M.get(C,C) : C in String].

create_map(Lower,Upper, N) = M =>
M = new_map(),
Len = Lower.length,
foreach(I in 1..Len)
II = (N+I) mod Len,
if II == 0 then II := Len end, % Adjust for 1 based
M.put(Upper[I],Upper[II]),
M.put(Lower[I],Lower[II])
end.```
Output:
```Picat> main
All human beings are born free and equal in dignity and rights.
Fqq mzrfs gjnslx fwj gtws kwjj fsi jvzfq ns inlsnyd fsi wnlmyx.
All human beings are born free and equal in dignity and rights.```

## PicoLisp

```(setq *Letters (apply circ (mapcar char (range 65 90))))

(de caesar (Str Key)
(pack
(mapcar '((C) (cadr (nth (member C *Letters) Key)))
(chop (uppc Str)) ) ) )```

Test:

```: (caesar "IBM" 25)
-> "HAL"
: (caesar @ 1)
-> "IBM"

: (caesar "The quick brown fox jumped over the lazy dog's back" 7)
-> "AOLXBPJRIYVDUMVEQBTWLKVCLYAOLSHGFKVNZIHJR"
: (caesar @ (- 26 7))
-> "THEQUICKBROWNFOXJUMPEDOVERTHELAZYDOGSBACK"```

## Pike

Pike has built in support for substitution cryptos in the Crypto module. It's possible to set the desired alphabet, but the default a-z matches the Caesar range.

```object c = Crypto.Substitution()->set_rot_key(2);
string msg     = "The quick brown fox jumped over the lazy dogs";
string msg_s2  = c->encrypt(msg);
c->set_rot_key(11);
string msg_s11 = c->encrypt(msg);
string decoded = c->decrypt(msg_s11);

write("%s\n%s\n%s\n%s\n", msg, msg_s2, msg_s11, decoded);```
Output:
```The quick brown fox jumped over the lazy dogs
Vjg swkem dtqyp hqz lworgf qxgt vjg ncba fqiu
Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozrd
The quick brown fox jumped over the lazy dogs
```

## PL/I

```caesar: procedure options (main);
declare cypher_string character (52) static initial
((2)'ABCDEFGHIJKLMNOPQRSTUVWXYZ');
declare (text, encyphered_text) character (100) varying,
offset fixed binary;

get edit (text) (L); /* Read in one line of text */
get list (offset);
if offset < 1 | offset > 25 then signal error;
put skip list ('Plain text=', text);

encyphered_text = translate(text, substr(cypher_string, offset+1, 26),
'ABCDEFGHIJKLMNOPQRSTUVWXYZ' );
put skip list ('Encyphered text=', encyphered_text);

text = translate(encyphered_text, substr(cypher_string, 27-offset, 26),
'ABCDEFGHIJKLMNOPQRSTUVWXYZ' );
put skip list ('Decyphered text=', text);

end caesar;```
Output:

with offset of 5

```Plain text=             THEQUICKBROWNFOXJUMPSOVERTHELAZYDOG
Encyphered text=        YMJVZNHPGWTBSKTCOZRUXTAJWYMJQFEDITL
Decyphered text=        THEQUICKBROWNFOXJUMPSOVERTHELAZYDOG
```

## PowerShell

```# Author: M. McNabb
function Get-CaesarCipher
{
Param
(
[Parameter(
Mandatory=\$true,ValueFromPipeline=\$true)]
[string]
\$Text,

[ValidateRange(1,25)]
[int]
\$Key = 1,

[switch]
\$Decode
)

begin
{
\$LowerAlpha = [char]'a'..[char]'z'
\$UpperAlpha = [char]'A'..[char]'Z'
}

process
{
\$Chars = \$Text.ToCharArray()

function encode
{
param
(
\$Char,
\$Alpha = [char]'a'..[char]'z'
)
\$Index = \$Alpha.IndexOf([int]\$Char)
\$NewIndex = (\$Index + \$Key) - \$Alpha.Length
\$Alpha[\$NewIndex]
}

function decode
{
param
(
\$Char,
\$Alpha = [char]'a'..[char]'z'
)
\$Index = \$Alpha.IndexOf([int]\$Char)
\$int = \$Index - \$Key
if (\$int -lt 0) {\$NewIndex = \$int + \$Alpha.Length}
else {\$NewIndex = \$int}
\$Alpha[\$NewIndex]
}

foreach (\$Char in \$Chars)
{
if ([int]\$Char -in \$LowerAlpha)
{
if (\$Decode) {\$Char = decode \$Char}
else {\$Char = encode \$Char}
}
elseif ([int]\$Char -in \$UpperAlpha)
{
if (\$Decode) {\$Char = decode \$Char \$UpperAlpha}
else {\$Char = encode \$Char \$UpperAlpha}
}

\$Char = [char]\$Char
[string]\$OutText += \$Char
}

\$OutText
\$OutText = \$null
}
}```

Usage examples:

```Encode:
PS C:\> 'Pack my box with five dozen liquor jugs.' | Get-CaesarCipher -key 3
Sdfn pb era zlwk ilyh grchq oltxru mxjv.

Decode:
PS C:\> 'Sdfn pb era zlwk ilyh grchq oltxru mxjv.' | Get-CaesarCipher -key 3 -Decode
Pack my box with five dozen liquor jugs.

Encode lines of text from a file:
PS C:\> Get-Content C:\Text.txt | Get-CaesarCipher -key 10
Vsxo yxo.
Vsxo dgy!
Vsxo drboo;
```

## Prolog

Works with: SWI-Prolog
Library: clpfd
```:- use_module(library(clpfd)).

caesar :-
L1 = "The five boxing wizards jump quickly",
writef("Original : %s\n", [L1]),

% encryption of the sentence
encoding(3, L1, L2) ,
writef("Encoding : %s\n", [L2]),

% deciphering on the encoded sentence
encoding(3, L3, L2),
writef("Decoding : %s\n", [L3]).

% encoding/decoding of a sentence
encoding(Key, L1, L2) :-
maplist(caesar_cipher(Key), L1, L2).

caesar_cipher(_, 32, 32) :- !.

caesar_cipher(Key, V1, V2) :-
V #= Key + V1,

% we verify that we are in the limits of A-Z and a-z.
((V1 #=< 0'Z #/\ V #> 0'Z) #\/ (V1 #=< 0'z #/\ V #> 0'z)
#\/
(V1 #< 0'A #/\ V2 #>= 0'A)#\/ (V1 #< 0'a #/\ V2 #>= 0'a)) #==> A,

% if we are not in these limits A is 1, otherwise 0.
V2 #= V - A * 26,

% compute values of V1 and V2
label([A, V1, V2]).```
Output:
``` ?- caesar.
Original : The five boxing wizards jump quickly
Encoding : Wkh ilyh eralqj zlcdugv mxps txlfnob
Decoding : The five boxing wizards jump quickly
true .
```

## PureBasic

The case is maintained for alphabetic characters (uppercase/lowercase input = uppercase/lowercase output) while non-alphabetic characters, if present are included and left unchanged in the result.

```Procedure.s CC_encrypt(plainText.s, key, reverse = 0)
;if reverse <> 0 then reverse the encryption (decrypt)
If reverse: reverse = 26: key = 26 - key: EndIf

Static alphabet\$ = "ABCEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz"

Protected result.s, i, length = Len(plainText), letter.s, legal
If key < 1 Or key > 25: ProcedureReturn: EndIf  ;keep key in range

For i = 1 To length
letter = Mid(plainText, i, 1)
legal = FindString(alphabet\$, letter, 1 + reverse)
If legal
result + Mid(alphabet\$, legal + key, 1)
Else
result + letter
EndIf
Next
ProcedureReturn result
EndProcedure

Procedure.s CC_decrypt(cypherText.s, key)
ProcedureReturn CC_encrypt(cypherText, key, 1)
EndProcedure

If OpenConsole()
Define key, plainText.s, encryptedText.s, decryptedText.s

key = Random(24) + 1 ;get a random key in the range 1 -> 25

plainText = "The quick brown fox jumped over the lazy dogs.": PrintN(RSet("Plain text = ", 17) + #DQUOTE\$ + plainText + #DQUOTE\$)
encryptedText = CC_encrypt(plainText, key): PrintN(RSet("Encrypted text = ", 17) + #DQUOTE\$ + encryptedText + #DQUOTE\$)
decryptedText = CC_decrypt(encryptedText, key): PrintN(RSet("Decrypted text = ", 17) + #DQUOTE\$ + decryptedText + #DQUOTE\$)

Print(#CRLF\$ + #CRLF\$ + "Press ENTER to exit"): Input()
CloseConsole()
EndIf```
Output:
```    Plain text = "The quick brown fox jumped over the lazy dogs."
Encrypted text = "Znk waoiq hxuct lud pasvkj ubkx znk rgfe jumy."
Decrypted text = "the quick brown fox jumped over the lazy dogs."```

### Alternate solution

Here is an alternate and more advanced form of the encrypt procedure. It improves on the simple version in terms of speed, in case Caesar is using the cipher on some very long documents. It is meant to replace the encrypt procedure in the previous code and produces identical results.

```Procedure.s CC_encrypt(text.s, key, reverse = 0)
;if reverse <> 0 then reverse the encryption (decrypt)
Protected i, *letter.Character, *resultLetter.Character, result.s = Space(Len(text))

If reverse: key = 26 - key: EndIf
If key < 1 Or key > 25: ProcedureReturn: EndIf  ;exit if key out of range

*letter = @text: *resultLetter = @result
While *letter\c
Select *letter\c
Case 'A' To 'Z'
*resultLetter\c = ((*letter\c - 65 + key) % 26) + 65
Case 'a' To 'z'
*resultLetter\c = ((*letter\c - 97 + key) % 26) + 97
Default
*resultLetter\c = *letter\c
EndSelect
*letter + SizeOf(Character): *resultLetter + SizeOf(Character)
Wend
ProcedureReturn result
EndProcedure```

## Python

```def caesar(s, k, decode = False):
if decode: k = 26 - k
return "".join([chr((ord(i) - 65 + k) % 26 + 65)
for i in s.upper()
if ord(i) >= 65 and ord(i) <= 90 ])

msg = "The quick brown fox jumped over the lazy dogs"
print msg
enc = caesar(msg, 11)
print enc
print caesar(enc, 11, decode = True)```
Output:
```The quick brown fox jumped over the lazy dogs
ESPBFTNVMCZHYQZIUFXAPOZGPCESPWLKJOZRD
THEQUICKBROWNFOXJUMPEDOVERTHELAZYDOGS```

Alternate solution

Works with: Python version 2.x

(for 3.x change `string.maketrans` to `str.maketrans`)

```import string
def caesar(s, k, decode = False):
if decode: k = 26 - k
return s.translate(
string.maketrans(
string.ascii_uppercase + string.ascii_lowercase,
string.ascii_uppercase[k:] + string.ascii_uppercase[:k] +
string.ascii_lowercase[k:] + string.ascii_lowercase[:k]
)
)
msg = "The quick brown fox jumped over the lazy dogs"
print msg
enc = caesar(msg, 11)
print enc
print caesar(enc, 11, decode = True)```
Output:
```The quick brown fox jumped over the lazy dogs
Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozrd
The quick brown fox jumped over the lazy dogs
```

Variant with memoization of translation tables

Works with: Python version 3.x
```import string
def caesar(s, k = 13, decode = False, *, memo={}):
if decode: k = 26 - k
k = k % 26
table = memo.get(k)
if table is None:
table = memo[k] = str.maketrans(
string.ascii_uppercase + string.ascii_lowercase,
string.ascii_uppercase[k:] + string.ascii_uppercase[:k] +
string.ascii_lowercase[k:] + string.ascii_lowercase[:k])
return s.translate(table)```

A compact alternative solution

```from string import ascii_uppercase as abc

def caesar(s, k, decode = False):
trans = dict(zip(abc, abc[(k,26-k)[decode]:] + abc[:(k,26-k)[decode]]))
return ''.join(trans[L] for L in s.upper() if L in abc)

msg = "The quick brown fox jumped over the lazy dogs"
print(caesar(msg, 11))
print(caesar(caesar(msg, 11), 11, True))```
Output:
```ESPBFTNVMCZHYQZIUFXAPOZGPCESPWLKJOZRD
THEQUICKBROWNFOXJUMPEDOVERTHELAZYDOGS
```

## QBasic

Works with: QBasic
Works with: QuickBasic
Works with: True BASIC

Note that TrueBasic uses '!' for comments

Translation of: BASIC256
```LET dec\$ = ""
LET tipo\$ = "cleartext "

PRINT "If decrypting enter 'd' -- else press enter ";
INPUT dec\$
PRINT "Enter offset ";
INPUT llave

IF dec\$ = "d" THEN
LET llave = 26 - llave
LET tipo\$ = "ciphertext "
END IF

PRINT "Enter "; tipo\$;

FOR i = 1 TO longitud
'LET itemp = ORD((cadena\$)[i:i+1-1][1:1]) 'True BASIC

IF iTemp > 64 AND iTemp < 91 THEN
LET iTemp = ((iTemp - 65) + llave) MOD 26   'QBasic
'LET iTemp = MOD(((iTemp - 65) + llave), 26) 'True BASIC
PRINT CHR\$(iTemp + 65);
ELSE
PRINT CHR\$(iTemp);
END IF
NEXT i
END```

## Quackery

```  [ dup upper != ]              is lower? ( c --> b )

[ dup lower != ]              is upper? ( c --> b )

[ swap \$ "" unrot witheach
[ dup lower? iff
[ over +
dup lower? not if
[ 26 - ] ]
else
[ dup upper? if
[ over +
dup upper? not if
[ 26 - ] ] ]
rot swap join swap ]
drop ]                      is caesar ( \$ --> \$ )

[ 26 swap - ]                 is decode ( n --> n )

\$ "Fere libenter homines id quod volunt credunt."
dup              echo\$ cr
23 caesar dup    echo\$ cr
23 decode caesar echo\$ cr```
Output:
```Fere libenter homines id quod volunt credunt.
Cbob ifybkqbo eljfkbp fa nrla slirkq zobarkq.
Fere libenter homines id quod volunt credunt.```

## R

This is a generalization of the Rot-13 solution for R at: http://rosettacode.org/wiki/Rot-13#R .

```# based on Rot-13 solution: http://rosettacode.org/wiki/Rot-13#R
ceasar <- function(x, key)
{
# if key is negative, wrap to be positive
if (key < 0) {
key <- 26 + key
}

old <- paste(letters, LETTERS, collapse="", sep="")
new <- paste(substr(old, key * 2 + 1, 52), substr(old, 1, key * 2), sep="")
chartr(old, new, x)
}

# simple examples from description
print(ceasar("hi",2))
print(ceasar("hi",20))

key <- 3
plaintext <- "The five boxing wizards jump quickly."
cyphertext <- ceasar(plaintext, key)
decrypted <- ceasar(cyphertext, -key)

print(paste("    Plain Text: ", plaintext, sep=""))
print(paste("   Cypher Text: ", cyphertext, sep=""))
print(paste("Decrypted Text: ", decrypted, sep=""))```
Output:
```> print(ceasar("hi",2))
[1] "jk"
> print(ceasar("hi",20))
[1] "bc"
> print(paste("Plain Text: ", plaintext, sep=""))
[1] "Plain Text: The five boxing wizards jump quickly."
> print(paste("Cypher Text: ", cyphertext, sep=""))
[1] "Cypher Text: Wkh ilyh eralqj zlcdugv mxps txlfnob."
> print(paste("Decrypted Text: ", decrypted, sep=""))
[1] "Decrypted Text: The five boxing wizards jump quickly."
```

## Racket

```#lang racket

(define A (char->integer #\A))
(define Z (char->integer #\Z))
(define a (char->integer #\a))
(define z (char->integer #\z))

(define (rotate c n)
(define cnum (char->integer c))
(define (shift base) (integer->char (+ base (modulo (+ n (- cnum base)) 26))))
(cond [(<= A cnum Z) (shift A)]
[(<= a cnum z) (shift a)]
[else c]))

(define (caesar s n)
(list->string (for/list ([c (in-string s)]) (rotate c n))))

(define (encrypt s) (caesar s 1))
(define (decrypt s) (caesar s -1))```

Example:

```> (define s (encrypt "The five boxing wizards jump quickly."))
> s
"Uif gjwf cpyjoh xjabset kvnq rvjdlmz."
> (decrypt s)
"The five boxing wizards jump quickly."
```

## Raku

(formerly Perl 6)

Works with: Rakudo version 2015.12
```my @alpha = 'A' .. 'Z';
sub encrypt ( \$key where 1..25, \$plaintext ) {
\$plaintext.trans( @alpha Z=> @alpha.rotate(\$key) );
}
sub decrypt ( \$key where 1..25, \$cyphertext ) {
\$cyphertext.trans( @alpha.rotate(\$key) Z=> @alpha );
}

my \$original = 'THE FIVE BOXING WIZARDS JUMP QUICKLY';
my \$en = encrypt( 13, \$original );
my \$de = decrypt( 13, \$en );

.say for \$original, \$en, \$de;

say 'OK' if \$original eq all( map { .&decrypt(.&encrypt(\$original)) }, 1..25 );```
Output:
```THE FIVE BOXING WIZARDS JUMP QUICKLY
GUR SVIR OBKVAT JVMNEQF WHZC DHVPXYL
THE FIVE BOXING WIZARDS JUMP QUICKLY
OK```

## Red

```Red ["Ceasar Cipher"]

rot: func [
char [char!]
key  [number!]
ofs  [char!]
][
to-char key + char - ofs // 26 + ofs
]

caesar: function [
src [string!]
key [integer!]
][
lower: charset [#"a" - #"z"]
upper: charset [#"A" - #"Z"]
parse src [
any [
change s: [lower (o: #"a") | upper (o: #"A")] (rot s/1 key o)
| skip
]
]
src
]

encrypt: :caesar
decrypt: func spec-of :caesar [caesar src negate key]```
```>> print encrypt "Ceasar Cipher" 4
Giewev Gmtliv
>> print decrypt "Giewev Gmtliv" 4
Ceasar Cipher
>>
```

## Retro

Retro provides a number of classical cyphers in the crypto' library. This implementation is from the library.

```{{
variable offset
: rotate  ( cb-c ) tuck - @offset + 26 mod + ;
: rotate? (  c-c )
dup 'a 'z within [ 'a rotate ] ifTrue
dup 'A 'Z within [ 'A rotate ] ifTrue ;
---reveal---
: ceaser  (  \$n-\$ )
!offset dup [ [ @ rotate? ] sip ! ] ^types'STRING each@ ;
}}

( Example )
"THEYBROKEOURCIPHEREVERYONECANREADTHIS" 3 ceaser   ( returns encrypted string )
23 ceaser   ( returns decrypted string )```

## REXX

### only Latin letters

This version conforms to the task's restrictions.

```/*REXX program supports the Caesar cipher for the Latin alphabet only,  */
/* no punctuation or blanks allowed, lowercase is treated as uppercase. */
Parse Upper Arg key text     /* get key & uppercased text to be ciphered*/
text=space(text,0)           /* elide any and blanks                    */
Say 'Caesar cipher key:' key      /* echo the Caesar cipher key         */
Say '       plain text:' text     /*   "   "       plain text           */
code=caesar(text,key)
Say '         ciphered:' code     /*   "   "    ciphered text           */
back=caesar(code,-key)
Say '       unciphered:' back     /*   "   "  unciphered text           */
If back\==text Then
Say "unciphered text doesn't match plain text."
Exit                              /* stick a fork in it,  we're all done*/
/*----------------------------------------------------------------------*/
caesar: Procedure
Parse Arg text,key
abc='ABCDEFGHIJKLMNOPQRSTUVWXYZ'
If abs(key)>length(abc)-1|key==0 Then
Call err 'key ('key') is invalid.'
badpos=verify(text,abc)          /* any illegal character in the text */
If key>0 Then                        /* cipher                        */
key2=key+1
Else                                 /* decipher                      */
key2=length(abc)+key+1
Return translate(text,substr(abc||abc,key2,length(abc)),abc)
/*----------------------------------------------------------------------*/
err:
Say
Say '***error***'
Say
Say arg(1)
Say
Exit 13```
output   when using the input of:     22 The definition of a trivial program is one that has no bugs
```Caesar cypher key: 22
plain text: THEDEFINITIONOFATRIVIALPROGRAMISONETHATHASNOBUGS
cyphered: PDAZABEJEPEKJKBWPNEREWHLNKCNWIEOKJAPDWPDWOJKXQCO
uncyphered: THEDEFINITIONOFATRIVIALPROGRAMISONETHATHASNOBUGS
```

### most characters

This version allows upper and lowercase Latin alphabet as well as all the characters on the standard (computer) keyboard including blanks.

```/*REXX program supports the Caesar cipher for most keyboard characters  */
/*                                                     including blanks.*/
Parse Arg key text                /* get key and the text to be ciph  */
Say 'Caesar cipher key:' key      /* echo the Caesar cipher key       */
Say '       plain text:' text     /* "   "       plain text           */
code=caesar(text,key)
Say '         ciphered:' code     /* "   "    ciphered text           */
back=caesar(code,-key)
Say '       unciphered:' back     /* "   "  unciphered text           */
If back\==text Then
Say "plain text doesn't match unciphered ciphered text."
Exit                           /* stick a fork in it,  we're all done */
/*----------------------------------------------------------------------*/
caesar: Procedure
Parse Arg txt,ky
abcx='abcdefghijklmnopqrstuvwxyz'
abcx=abcx'~!@#\$%^&*_+:";?,./`-= ' /* also add other characters     */
l=length(abcx)                       /* obtain the length of abcx     */
aky=abs(ky)                          /* absolute value of the key     */
If aky>length(abcx)-1|ky==0 Then
Call err ky 'key is invalid.'
badpos=verify(txt,abcx)              /* any illegal character in txt  */
If ky>0 Then                          /* cipher                        */
ky=ky+1
Else                                 /* decipher                      */
ky=l+1-aky
/* return translated input       */
Return translate(txt,substr(abcx||abcx,ky,l),abcx)
/*----------------------------------------------------------------------*/
err:
Say
Say '***error***'
Say
Say arg(1)
Say
Exit 13```
output   when using the input of:     31 Batman's hood is called a "cowl" (old meaning).
```Caesar cypher key: 31
plain text: Batman's hood is called a "cowl" (old meaning).
cyphered: g5^>5~e%d{!!8d}%d75<<98d5dU7!_<UdA!<8d>95~}~)BY
uncyphered: Batman's hood is called a "cowl" (old meaning).
```

## Ring

```# Project : Caesar cipher

cipher = "pack my box with five dozen liquor jugs"
abc = "abcdefghijklmnopqrstuvwxyz"
see "text is to be encrypted:" + nl
see cipher+ nl + nl
str = ""
key = random(24) + 1
see "key = " + key + nl + nl
see "encrypted:" + nl
caesarencode(cipher, key)
see str + nl + nl
cipher = str
see "decrypted again:" + nl
caesardecode(cipher, key)
see str + nl

func caesarencode(cipher, key)
str = ""
for n = 1 to len(cipher)
if cipher[n] != " "
pos = substr(abc, cipher[n])
if pos + key < len(abc)
str = str + abc[pos + key]
else
if (pos+key)-len(abc) != 0
str = str + abc[(pos+key)%len(abc)]
else
str = str +abc[key+pos]
ok
ok
else
str = str + " "
ok
next
return str

func caesardecode(cipher, key)
str = ""
for n= 1 to len(cipher)
if cipher[n] != " "
pos = substr(abc, cipher[n])
if (pos - key) > 0 and pos != key
str = str + abc[pos - key]
loop
else
if pos = key
str = str + char(122)
else
str = str + abc[len(abc)-(key-pos)]
ok
ok
else
str = str + " "
ok
next
return str```

Output:

```text is to be encrypted:
pack my box with five dozen liquor jugs

key = 9

encrypted:
yjlt vh kxg frcq oren mxinw urzdxa sdpb

decrypted again:
pack my box with five dozen liquor jugs
```

## RPL

Works with: Halcyon Calc version 4.2.7
```≪ → a shift
≪ IF DUP a ≥ LAST 26 + < AND
THEN a - shift + 26 MOD a + END
≫ ≫ ‘Rotate’ STO

≪ → string shift
≪ "" 1 string SIZE FOR j
string j DUP SUB NUM
65 shift Rotate 90 shift Rotate
CHR +
NEXT
≫ 'CESAR' STO
```
```  ( m a shift -- n )
if m in [a, a+26[
then shift it modulo 26

( string shift -- string )
Scan input string
extract jth ASCII code
shift if [A..Z] or [a..z]
back to character

```

The following line of command delivers what is required:

```"The quick brown fox jumped over the lazy dogs" CESAR
```
Output:
```1: "Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozrd"
```

## Ruby

```class String
ALFABET = ("A".."Z").to_a

def caesar_cipher(num)
self.tr(ALFABET.join, ALFABET.rotate(num).join)
end

end

#demo:
decrypted = encypted.caesar_cipher(-3)```

## Run BASIC

```input "Gimme a ofset:";ofst       ' set any offset you like

a\$ = "Pack my box with five dozen liquor jugs"
print " Original: ";a\$
a\$ = cipher\$(a\$,ofst)
print "Encrypted: ";a\$
print "Decrypted: ";cipher\$(a\$,ofst+6)

FUNCTION cipher\$(a\$,ofst)
for i = 1 to len(a\$)
aa\$   = mid\$(a\$,i,1)
code\$ = " "
if aa\$ <> " " then
ua\$   = upper\$(aa\$)
a     = asc(ua\$) - 64
code\$ = chr\$((((a mod 26) + ofst) mod 26) + 65)
if ua\$ <> aa\$ then code\$ = lower\$(code\$)
end if
cipher\$ = cipher\$;code\$
next i
END FUNCTION```
Output:
```Gimme a ofset:?9
Original: Pack my box with five dozen liquor jugs
Encrypted: Zkmu wi lyh gsdr psfo nyjox vsaeyb teqc
Decrypted: Pack my box with five dozen liquor jugs```

## Rust

This example shows proper error handling. It skips non-ASCII characters.

```use std::io::{self, Write};
use std::fmt::Display;
use std::{env, process};

fn main() {
let shift: u8 = env::args().nth(1)
.unwrap_or_else(|| exit_err("No shift provided", 2))
.parse()
.unwrap_or_else(|e| exit_err(e, 3));

let plain = get_input()
.unwrap_or_else(|e| exit_err(&e, e.raw_os_error().unwrap_or(-1)));

let cipher = plain.chars()
.map(|c| {
let case = if c.is_uppercase() {'A'} else {'a'} as u8;
if c.is_alphabetic() { (((c as u8 - case + shift) % 26) + case) as char } else { c }
}).collect::<String>();

println!("Cipher text: {}", cipher.trim());
}

fn get_input() -> io::Result<String> {
print!("Plain text:  ");
try!(io::stdout().flush());

let mut buf = String::new();
Ok(buf)
}

fn exit_err<T: Display>(msg: T, code: i32) -> ! {
let _ = writeln!(&mut io::stderr(), "ERROR: {}", msg);
process::exit(code);
}```

## Scala

```object Caesar {
private val alphaU='A' to 'Z'
private val alphaL='a' to 'z'

def encode(text:String, key:Int)=text.map{
case c if alphaU.contains(c) => rot(alphaU, c, key)
case c if alphaL.contains(c) => rot(alphaL, c, key)
case c => c
}
def decode(text:String, key:Int)=encode(text,-key)
}```
```val text="The five boxing wizards jump quickly"
println("Plaintext  => " + text)
val encoded=Caesar.encode(text, 3)
println("Ciphertext => " + encoded)
println("Decrypted  => " + Caesar.decode(encoded, 3))```
Output:
```Plaintext  => The five boxing wizards jump quickly
Ciphertext => Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted  => The five boxing wizards jump quickly```

### Alternate version

This version first creates non shifted and shifted character sequences and then encodes and decodes by indexing between those sequences.

```class Caeser(val key: Int) {
@annotation.tailrec
private def rotate(p: Int, s: IndexedSeq[Char]): IndexedSeq[Char] = if (p < 0) rotate(s.length + p, s) else s.drop(p) ++ s.take(p)

val uc = 'A' to 'Z'
val lc = 'a' to 'z'
val as = uc ++ lc
val bs = rotate(key, uc) ++ rotate(key, lc)

def encode(c: Char) = if (as.contains(c)) bs(as.indexOf(c)) else c
def decode(c: Char) = if (bs.contains(c)) as(bs.indexOf(c)) else c
}```
```val text = "The five boxing wizards jump quickly"
val myCaeser = new Caeser(3)
val encoded = text.map(c => myCaeser.encode(c))
println("Plaintext => " + text)
println("Ciphertext => " + encoded)
println("Decrypted => " + encoded.map(c => myCaeser.decode(c)))```
Output:
```Plaintext => The five boxing wizards jump quickly
Ciphertext => Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted => The five boxing wizards jump quickly```

## Scheme

```;
; Works with R7RS-compatible Schemes (e.g. Chibi).
; Also current versions of Chicken, Gauche and Kawa.
;
(cond-expand
(chicken (use srfi-13))
(gauche  (use srfi-13))
(kawa    (import (srfi :13)))
(else    (import (scheme base) (scheme write)))) ; R7RS

(define msg "The quick brown fox jumps over the lazy dog.")
(define key 13)

(define (caesar char)
(define A (char->integer #\A))
(define Z (char->integer #\Z))
(define a (char->integer #\a))
(define z (char->integer #\z))
(define c (char->integer char))
(integer->char
(cond ((<= A c Z) (+ A (modulo (+ key (- c A)) 26)))
((<= a c z) (+ a (modulo (+ key (- c a)) 26)))
(else c)))) ; Return other characters verbatim.

(display (string-map caesar msg))
(newline)```
Output:
```Gur dhvpx oebja sbk whzcf bire gur ynml qbt.
```

## sed

This code is roughly equivalent to the rot-13 cypher sed implementation, except that the conversion table is parameterized by a number and that the conversion done manually, instead of using `y///' command.

```#!/bin/sed -rf
# Input: <number 0..25>\ntext to encode

/^[0-9]+\$/ {
# validate a number and translate it to analog form
s/\$/;9876543210dddddddddd/
s/([0-9]);.*\1.{10}(.?)/\2/
s/2/11/
s/1/dddddddddd/g
/[3-9]|d{25}d+/ {
s/.*/Error: Key must be <= 25/
q
}
# append from-table
s/\$/\nabcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/
# .. and to-table
s/\$/abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/
# rotate to-table, lower and uppercase independently, removing one `d' at a time
: rotate
s/^d(.*\n[^Z]+Z)(.)(.{25})(.)(.{25})/\1\3\2\5\4/
t rotate
s/\n//
h
d
}

# use \n to mark character to convert
s/^/\n/
# append conversion table to pattern space
G
: loop
# look up converted character and place it instead of old one
s/\n(.)(.*\n.*\1.{51}(.))/\n\3\2/
# advance \n even if prev. command fails, thus skip non-alphabetical characters
/\n\n/! s/\n([^\n])/\1\n/
t loop
s/\n\n.*//```
Output:
```\$ ./caesar.sed
3
The five boxing wizards jump quickly
Wkh ilyh eralqj zlcdugv mxps txlfnob
23
Wkh ilyh eralqj zlcdugv mxps txlfnob
The five boxing wizards jump quickly
26
Error: Key must be <= 25
```

## Seed7

```\$ include "seed7_05.s7i";

const func string: rot (in string: stri, in integer: encodingKey) is func
result
var string: encodedStri is "";
local
var char: ch is ' ';
var integer: index is 0;
begin
encodedStri := stri;
for ch key index range stri do
if ch >= 'a' and ch <= 'z' then
ch := chr((ord(ch) - ord('a') + encodingKey) rem 26 + ord('a'));
elsif ch >= 'A' and ch <= 'Z' then
ch := chr((ord(ch) - ord('A') + encodingKey) rem 26 + ord('A'));
end if;
encodedStri @:= [index] ch;
end for;
end func;

const proc: main is func
local
const integer: exampleKey is 3;
const string: testText is "The five boxing wizards jump quickly";
begin
writeln("Original:  " <& testText);
writeln("Encrypted: " <& rot(testText, exampleKey));
writeln("Decrypted: " <& rot(rot(testText, exampleKey), 26 - exampleKey));
end func;```
Output:
```Original:  The five boxing wizards jump quickly
Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted: The five boxing wizards jump quickly
```

## SequenceL

You only have to write an encrypt and decrypt function for characters. The semantics of Normalize Transpose allow those functions to be applied to strings.

```import <Utilities/Sequence.sl>;
import <Utilities/Conversion.sl>;

lowerAlphabet := "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
upperAlphabet := "abcdefghijklmnopqrstuvwxyz";

caesarEncrypt(ch, key) :=
let
correctAlphabet :=
lowerAlphabet when some(ch = lowerAlphabet)
else
upperAlphabet;

index := Sequence::firstIndexOf(correctAlphabet, ch);

newIndex := (index + key - 1) mod 26 + 1;
in
ch when not(some(ch = lowerAlphabet) or some(ch = upperAlphabet))
else
correctAlphabet[newIndex];

caesarDecrypt(ch, key) := caesarEncrypt(ch, 26 - key);

main(args(2)) :=
let
key := Conversion::stringToInt(args[2]);
encrypted := caesarEncrypt(args[1], key);
decrypted := caesarDecrypt(encrypted, key);
in
"Input: \t" ++ args[1] ++ "\n" ++
"Encrypted:\t" ++ encrypted ++ "\n" ++
"Decrypted:\t" ++ decrypted;```
Output:
```cmd:> main.exe "Pack my box with five dozen liquor jugs." 5
"Original: Pack my box with five dozen liquor jugs.
Encrypted: Ufhp rd gtc bnym knaj itejs qnvztw ozlx.
Decrypted: Pack my box with five dozen liquor jugs."
```

## Sidef

Translation of: Perl
```func caesar(msg, key, decode=false) {
decode && (key = (26 - key));
msg.gsub(/([A-Z])/i, {|c| ((c.uc.ord - 65 + key) % 26) + 65 -> chr});
};

var msg = 'THE FIVE BOXING WIZARDS JUMP QUICKLY';

var enc = caesar(msg, 10);
var dec = caesar(enc, 10, true);

say "msg: #{msg}";
say "enc: #{enc}";
say "dec: #{dec}";```
Output:
```msg: THE FIVE BOXING WIZARDS JUMP QUICKLY
enc: DRO PSFO LYHSXQ GSJKBNC TEWZ AESMUVI
dec: THE FIVE BOXING WIZARDS JUMP QUICKLY
```

## Sinclair ZX81 BASIC

Works with 1k of RAM. A negative key decodes.

``` 10 INPUT KEY
20 INPUT T\$
30 LET C\$=""
40 FOR I=1 TO LEN T\$
50 LET L\$=T\$(I)
60 IF L\$<"A" OR L\$>"Z" THEN GOTO 100
70 LET L\$=CHR\$ (CODE L\$+KEY)
80 IF L\$>"Z" THEN LET L\$=CHR\$ (CODE L\$-26)
90 IF L\$<"A" THEN LET L\$=CHR\$ (CODE L\$+26)
100 LET C\$=C\$+L\$
110 NEXT I
120 PRINT C\$```
Input:
```12
GALLIA EST OMNIS DIVISA IN PARTES TRES```
Output:
`SMXXUM QEF AYZUE PUHUEM UZ BMDFQE FDQE`
Input:
```-12
SMXXUM QEF AYZUE PUHUEM UZ BMDFQE FDQE```
Output:
`GALLIA EST OMNIS DIVISA IN PARTES TRES`

## Smalltalk

Works with: Smalltalk/X

well, I'm lucky: the standard library already contains a rot:n method!

`'THE QUICK BROWN FOX' rot:3 -> 'WKH TXLFN EURZQ IRA'`

but if it wasn't, here is an implementation for other smalltalks:

```!CharacterArray methodsFor:'encoding'!
rot:n
^ self class
streamContents:[:aStream |
self do:[:char |
aStream nextPut:(char rot:n) ]]

!Character methodsFor:'encoding'!
rot:n
(self isLetter) ifTrue:[
self isLowercase ifTrue:[
^ 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz' at:(self-\$a+1+n)
] ifFalse:[
^ 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ' at:(self-\$A+1+n)
]
].
^ self```

## SparForte

As a structured script.

```#!/usr/local/bin/spar
pragma annotate( summary, "caesar" )
@( description, "Implement a Caesar cipher, both encoding and ")
@( description, "decoding.  The key is an integer from 1 to " )
@( description, "25.  This cipher rotates (either towards left ")
@( description, "or right) the letters of the alphabet (A to " )
@( description, "Z). " )
@( see_also, "http://rosettacode.org/wiki/Caesar_cipher" )
@( author, "Ken O. Burtch" );

pragma restriction( no_external_commands );

procedure caesar is

type cipher_value is new natural;

function to_cipher_value(c: character; offset: character) return cipher_value is
cv : integer;
begin
cv := ( numerics.pos(c)-numerics.pos(offset) ) mod 26;
return cipher_value(cv);
end to_cipher_value;

function to_character(cv: cipher_value; offset: character) return character is
begin
return strings.val( integer(cv) + numerics.pos(offset) );
end to_character;

function encrypt( plain: string; key: cipher_value) return string is
cv : cipher_value;
cipher_char : character;
cipher_text : string;
plain_char  : character;
begin
for i in 1..strings.length( plain ) loop
plain_char := strings.element( plain, i);
if plain_char >= 'A' and plain_char <= 'Z' then
cv := ( to_cipher_value( plain_char, 'A')+key ) mod 26;
cipher_char := to_character( cv, 'A' );
elsif plain_char >= 'a' and plain_char <= 'z' then
cv := ( to_cipher_value( plain_char, 'a')+key ) mod 26;
cipher_char := to_character( cv, 'a' );
else
cipher_char := plain_char;
end if;
cipher_text := strings.overwrite( @, i, string( cipher_char ) );
end loop;
return cipher_text;
end encrypt;

text:  string := get_line;
key: constant cipher_value := 3; -- Default key from "Commentarii de Bello Gallico"

begin
put_line("Plaintext ------------>" & text);
text := encrypt(text, key);
put_line("Ciphertext ----------->" & text);
text := encrypt(text, -key);
put_line("Decrypted Ciphertext ->" & text);
end caesar;```

## SSEM

ASCII didn't exit in 1948, and the task specification explicitly says we only need to convert Roman capitals; so we adopt a simpler encoding, representing the letters of the alphabet from A=0 to Z=25.

The program will convert one character at a time. Load the character code into storage address 20, and the key into address 19. The machine will halt with the cyphered encoding in the accumulator. A negative (two's complement) key decodes.

This is in fact a general solution that will work equally well with alphabets of more or fewer than 26 characters: simply replace the constant 26 in storage address 18 with 22 for Hebrew, 24 for Greek, 28 for Arabic, 33 for Russian, etc.

```00101000000000100000000000000000   0. -20 to c
11001000000000010000000000000000   1. Sub. 19
10101000000001100000000000000000   2. c to 21
10101000000000100000000000000000   3. -21 to c
00000000000000110000000000000000   4. Test
10001000000000000000000000000000   5. 17 to CI
10101000000001100000000000000000   6. c to 21
10101000000000100000000000000000   7. -21 to c
01001000000000010000000000000000   8. Sub. 18
10101000000001100000000000000000   9. c to 21
10101000000000100000000000000000  10. -21 to c
00000000000001110000000000000000  11. Stop
01001000000000010000000000000000  12. Sub. 18
00000000000000110000000000000000  13. Test
00000000000001110000000000000000  14. Stop
10101000000000100000000000000000  15. -21 to c
00000000000001110000000000000000  16. Stop
11010000000000000000000000000000  17. 11
01011000000000000000000000000000  18. 26```

## Stata

```function caesar(s, k) {
u = ascii(s)
i = selectindex(u:>=65 :& u:<=90)
if (length(i)>0) u[i] = mod(u[i]:+(k-65), 26):+65
i = selectindex(u:>=97 :& u:<=122)
if (length(i)>0) u[i] = mod(u[i]:+(k-97), 26):+97
return(char(u))
}

caesar("layout", 20)
fusion```

## Swift

```func usage(_ e:String) {
print("error: \(e)")
print("./caeser -e 19 a-secret-string")
print("./caeser -d 19 tskxvjxlskljafz")
}

func charIsValid(_ c:Character) -> Bool {
return c.isASCII && ( c.isLowercase || 45 == c.asciiValue ) // '-' = 45
}

func charRotate(_ c:Character, _ by:Int) -> Character {
var cv:UInt8! = c.asciiValue
if 45 == cv { cv = 96 }  // if '-', set it to 'a'-1
cv += UInt8(by)
if 122 < cv { cv -= 27 } // if larget than 'z', reduce by 27
if 96 == cv { cv = 45 }  // restore '-'
return Character(UnicodeScalar(cv))
}

func caesar(_ enc:Bool, _ key:Int, _ word:String) -> String {
let r = enc ? key : 27 - key
func charRotateWithKey(_ c:Character) -> Character {
return charRotate(c,r)
}
return String(word.map(charRotateWithKey))
}

func main() {
var encrypt = true

if 4 != CommandLine.arguments.count {
return usage("caesar expects exactly three arguments")
}

switch ( CommandLine.arguments[1] ) {
case "-e":
encrypt = true
case "-d":
encrypt = false
default:
return usage("first argument must be -e (encrypt) or -d (decrypt)")
}

guard let key = Int(CommandLine.arguments[2]) else {
return usage("second argument not a number (must be in range 0-26)")
}

if key < 0 || 26 < key {
return usage("second argument not in range 0-26")
}

if !CommandLine.arguments[3].allSatisfy(charIsValid) {
return usage("third argument must only be lowercase ascii characters, or -")
}

let ans = caesar(encrypt,key,CommandLine.arguments[3])
print("\(ans)")
}

func test() {
if ( Character("a") != charRotate(Character("a"),0) ) {
print("Test Fail 1")
}
if ( Character("-") != charRotate(Character("-"),0) ) {
print("Test Fail 2")
}
if ( Character("-") != charRotate(Character("z"),1) ) {
print("Test Fail 3")
}
if ( Character("z") != charRotate(Character("-"),26)) {
print("Test Fail 4")
}
if ( "ihgmkzma" != caesar(true,8,"a-zecret") ) {
print("Test Fail 5")
}
if ( "a-zecret" != caesar(false,8,"ihgmkzma") ) {
print("Test Fail 6")
}
}

test()
main()```

## Tcl

```package require Tcl 8.6;    # Or TclOO package for 8.5

oo::class create Caesar {
variable encryptMap decryptMap
constructor shift {
for {set i 0} {\$i < 26} {incr i} {
# Play fast and loose with string/list duality for shorter code
append encryptMap [format "%c %c %c %c " \
[expr {\$i+65}] [expr {(\$i+\$shift)%26+65}] \
[expr {\$i+97}] [expr {(\$i+\$shift)%26+97}]]
append decryptMap [format "%c %c %c %c " \
[expr {\$i+65}] [expr {(\$i-\$shift)%26+65}] \
[expr {\$i+97}] [expr {(\$i-\$shift)%26+97}]]
}
}

method encrypt text {
string map \$encryptMap \$text
}
method decrypt text {
string map \$decryptMap \$text
}
}```

Demonstrating:

```set caesar [Caesar new 3]
set txt "The five boxing wizards jump quickly."
set enc [\$caesar encrypt \$txt]
set dec [\$caesar decrypt \$enc]
puts "Original message  = \$txt"
puts "Encrypted message = \$enc"
puts "Decrypted message = \$dec"```
Output:
```Original message  = The five boxing wizards jump quickly.
Encrypted message = Wkh ilyh eralqj zlcdugv mxps txlfnob.
Decrypted message = The five boxing wizards jump quickly.
```

## True BASIC

Works with: QBasic
Translation of: BASIC256
```LET dec\$ = ""
LET tipo\$ = "cleartext "

PRINT "If decrypting enter 'd' -- else press enter ";
INPUT dec\$
PRINT "Enter offset ";
INPUT llave

IF dec\$ = "d" THEN
LET llave = 26 - llave
LET tipo\$ = "ciphertext "
END IF

PRINT "Enter "; tipo\$;

FOR i = 1 TO longitud
LET itemp = ORD((cadena\$)[i:i+1-1][1:1])  !'True BASIC

IF iTemp > 64 AND iTemp < 91 THEN
!LET iTemp = ((iTemp - 65) + llave) MOD 26    'QBasic
LET iTemp = MOD(((iTemp - 65) + llave), 26)  !'True BASIC
PRINT CHR\$(iTemp + 65);
ELSE
PRINT CHR\$(iTemp);
END IF
NEXT i
END```

## TUSCRIPT

```\$\$ MODE TUSCRIPT
text="THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG"
PRINT "text orginal    ",text

abc="ABCDEFGHIJKLMNOPQRSTUVWXYZ",key=3,caesarskey=key+1
secretbeg=EXTRACT (abc,#caesarskey,0)
secretend=EXTRACT (abc,0,#caesarskey)
secretabc=CONCAT (secretbeg,secretend)

abc=STRINGS (abc,":</:"),secretabc=STRINGS (secretabc,":</:")
abc=SPLIT (abc),         secretabc=SPLIT (secretabc)
abc2secret=JOIN(abc," ",secretabc),secret2abc=JOIN(secretabc," ",abc)

BUILD X_TABLE abc2secret=*
DATA  {abc2secret}

BUILD X_TABLE secret2abc=*
DATA  {secret2abc}

ENCODED = EXCHANGE (text,abc2secret)
PRINT "text encoded    ",encoded

DECODED = EXCHANGE (encoded,secret2abc)
PRINT "encoded decoded ",decoded```
Output:
```text orginal    THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
text encoded    WKH TXLFN EURZQ IRA MXPSV RYHU WKH ODCB GRJ
encoded decoded THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
```

## TXR

The strategy here, one of many possible ones, is to build, at run time,the arguments to be passed to deffilter to construct a pair of filters `enc` and `dec` for encoding and decoding. Filters are specified as tuples of strings.

```@(next :args)
@(cases)
@{key /[0-9]+/}
@text
@(or)
@  (throw error "specify <key-num> <text>")
@(end)
@(do
(defvar k (int-str key 10)))
@(bind enc-dec
@(collect-each ((i (range 0 25)))
(let* ((p (tostringp (+ #\a i)))
(e (tostringp (+ #\a (mod (+ i k) 26))))
(P (upcase-str p))
(E (upcase-str e)))
^(((,p ,e) (,P ,E))
((,e ,p) (,E ,P))))))
@(deffilter enc . @(mappend (fun first) enc-dec))
@(deffilter dec . @(mappend (fun second) enc-dec))
@(output)
encoded: @{text :filter enc}
decoded: @{text :filter dec}
@(end)```
Output:
```\$ ./txr caesar.txr 12 'Hello, world!'
decoded: Vszzc, kcfzr!
\$ ./txr caesar.txr 12 'Vszzc, kcfzr!'
encoded: Hello, world!
decoded: Jgnnq, yqtnf!
```

## TypeScript

```function replace(input: string, key: number) : string {
return input.replace(/([a-z])/g,
(\$1) => String.fromCharCode((\$1.charCodeAt(0) + key + 26 - 97) % 26 + 97)
).replace(/([A-Z])/g,
(\$1) => String.fromCharCode((\$1.charCodeAt(0) + key + 26 - 65) % 26 + 65));
}

// test
var str = 'The five boxing wizards jump quickly';
var encoded = replace(str, 3);
var decoded = replace(encoded, -3);

console.log('Enciphered: ' + encoded);
console.log('Deciphered: ' + decoded);```

## UNIX Shell

Works with: bash

I added a tr function to make this "pure" bash. In practice, you'd remove that function and use the external tr utility.

```caesar() {
local OPTIND
local encrypt n=0
while getopts :edn: option; do
case \$option in
e) encrypt=true ;;
d) encrypt=false ;;
n) n=\$OPTARG ;;
:) echo "error: missing argument for -\$OPTARG" >&2
return 1 ;;
?) echo "error: unknown option -\$OPTARG" >&2
return 1 ;;
esac
done
shift \$((OPTIND-1))
if [[ -z \$encrypt ]]; then
echo "error: specify one of -e or -d" >&2
return 1
fi

local upper=ABCDEFGHIJKLMNOPQRSTUVWXYZ
local lower=abcdefghijklmnopqrstuvwxyz
if \$encrypt; then
tr "\$upper\$lower" "\${upper:n}\${upper:0:n}\${lower:n}\${lower:0:n}" <<< "\$1"
else
tr "\${upper:n}\${upper:0:n}\${lower:n}\${lower:0:n}" "\$upper\$lower" <<< "\$1"
fi
}

tr() {
local -A charmap
local i trans line char
for ((i=0; i<\${#1}; i++)); do
charmap[\${1:i:1}]=\${2:i:1}
done
while IFS= read -r line; do
trans=""
for ((i=0; i<\${#line}; i++)); do
char=\${line:i:1}
if [[ -n \${charmap[\$char]} ]]; then
trans+=\${charmap[\$char]}
else
trans+=\$char
fi
done
echo "\$trans"
done
}

txt="The five boxing wizards jump quickly."
enc=\$(caesar -e -n 5 "\$txt")
dec=\$(caesar -d -n 5 "\$enc")

echo "original:  \$txt"
echo "encrypted: \$enc"
echo "decrypted: \$dec"```
Output:
```original:  The five boxing wizards jump quickly.
encrypted: Ymj knaj gtcnsl bnefwix ozru vznhpqd.
decrypted: The five boxing wizards jump quickly.```

## Ursa

```decl string mode
while (not (or (= mode "encode") (= mode "decode")))
out "encode/decode: " console
set mode (lower (in string console))
end while

decl string message
out "message:       " console
set message (upper (in string console))

decl int key
out "key:           " console
set key (in int console)
if (or (> key 26) (< key 0))
out endl "invalid key" endl console
stop
end if

if (= mode "decode")
set key (int (- 26 key))
end if

for (decl int i) (< i (size message)) (inc i)
if (and (> (ord message<i>) 64) (< (ord message<i>) 91))
out (chr (int (+ (mod (int (+ (- (ord message<i>) 65) key)) 26) 65))) console
end if
end for
out endl console```

## Ursala

The reification operator (`-:`) generates efficient code for applications like this given a table of inputs and outputs, which is obtained in this case by zipping the alphabet with itself rolled the right number of times, done separately for the upper and lower case letters and then combined.

```#import std
#import nat

enc "n" = * -:~&@T ^p(rep"n" ~&zyC,~&)~~K30K31X letters    # encryption function
dec "n" = * -:~&@T ^p(~&,rep"n" ~&zyC)~~K30K31X letters    # decryption function

plaintext = 'the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY'

#show+ # exhaustive test

test = ("n". <.enc"n",dec"n"+ enc"n"> plaintext)*= nrange/1 25```
Output:
```uif gjwf cpyjoh xjabset kvnq rvjdlmz UIF GJWF CPYJOH XJABSET KVNQ RVJDLMZ
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
vjg hkxg dqzkpi ykbctfu lwor swkemna VJG HKXG DQZKPI YKBCTFU LWOR SWKEMNA
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
wkh ilyh eralqj zlcdugv mxps txlfnob WKH ILYH ERALQJ ZLCDUGV MXPS TXLFNOB
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
xli jmzi fsbmrk amdevhw nyqt uymgopc XLI JMZI FSBMRK AMDEVHW NYQT UYMGOPC
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
ymj knaj gtcnsl bnefwix ozru vznhpqd YMJ KNAJ GTCNSL BNEFWIX OZRU VZNHPQD
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
znk lobk hudotm cofgxjy pasv waoiqre ZNK LOBK HUDOTM COFGXJY PASV WAOIQRE
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
aol mpcl ivepun dpghykz qbtw xbpjrsf AOL MPCL IVEPUN DPGHYKZ QBTW XBPJRSF
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
bpm nqdm jwfqvo eqhizla rcux ycqkstg BPM NQDM JWFQVO EQHIZLA RCUX YCQKSTG
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
cqn oren kxgrwp frijamb sdvy zdrltuh CQN OREN KXGRWP FRIJAMB SDVY ZDRLTUH
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
dro psfo lyhsxq gsjkbnc tewz aesmuvi DRO PSFO LYHSXQ GSJKBNC TEWZ AESMUVI
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
esp qtgp mzityr htklcod ufxa bftnvwj ESP QTGP MZITYR HTKLCOD UFXA BFTNVWJ
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
ftq ruhq najuzs iulmdpe vgyb cguowxk FTQ RUHQ NAJUZS IULMDPE VGYB CGUOWXK
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
gur svir obkvat jvmneqf whzc dhvpxyl GUR SVIR OBKVAT JVMNEQF WHZC DHVPXYL
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
hvs twjs pclwbu kwnofrg xiad eiwqyzm HVS TWJS PCLWBU KWNOFRG XIAD EIWQYZM
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
iwt uxkt qdmxcv lxopgsh yjbe fjxrzan IWT UXKT QDMXCV LXOPGSH YJBE FJXRZAN
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
jxu vylu renydw mypqhti zkcf gkysabo JXU VYLU RENYDW MYPQHTI ZKCF GKYSABO
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
kyv wzmv sfozex nzqriuj aldg hlztbcp KYV WZMV SFOZEX NZQRIUJ ALDG HLZTBCP
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
lzw xanw tgpafy oarsjvk bmeh imaucdq LZW XANW TGPAFY OARSJVK BMEH IMAUCDQ
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
max ybox uhqbgz pbstkwl cnfi jnbvder MAX YBOX UHQBGZ PBSTKWL CNFI JNBVDER
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
nby zcpy vircha qctulxm dogj kocwefs NBY ZCPY VIRCHA QCTULXM DOGJ KOCWEFS
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
ocz adqz wjsdib rduvmyn ephk lpdxfgt OCZ ADQZ WJSDIB RDUVMYN EPHK LPDXFGT
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
pda bera xktejc sevwnzo fqil mqeyghu PDA BERA XKTEJC SEVWNZO FQIL MQEYGHU
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
qeb cfsb ylufkd tfwxoap grjm nrfzhiv QEB CFSB YLUFKD TFWXOAP GRJM NRFZHIV
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
rfc dgtc zmvgle ugxypbq hskn osgaijw RFC DGTC ZMVGLE UGXYPBQ HSKN OSGAIJW
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
sgd ehud anwhmf vhyzqcr itlo pthbjkx SGD EHUD ANWHMF VHYZQCR ITLO PTHBJKX
the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY```

## Vala

This is a port of the C# code present in this page.

```static void println(string str) {
stdout.printf("%s\r\n", str);
}

static unichar encrypt_char(unichar ch, int code) {
if (!ch.isalpha()) return ch;

unichar offset = ch.isupper() ? 'A' : 'a';
return (unichar)((ch + code - offset) % 26 + offset);
}

static string encrypt(string input, int code) {
var builder = new StringBuilder();

unichar c;
for (int i = 0; input.get_next_char(ref i, out c);) {
builder.append_unichar(encrypt_char(c, code));
}

return builder.str;
}

static string decrypt(string input, int code) {
return encrypt(input, 26 - code);
}

const string test_case = "The quick brown fox jumped over the lazy dog";

void main() {
println(test_case);
println(encrypt(test_case, -1));
println(decrypt(encrypt(test_case, -1), -1));
}```
Output:
```The quick brown fox jumped over the lazy dog
Sgd pthbj aqnvm enw itlodc nudq sgd kvyx cnf
The quick brown fox jumped over the lwzy dog
```

## VBA

```Option Explicit

Sub Main_Caesar()
Dim ch As String
ch = Caesar_Cipher("CAESAR: Who is it in the press that calls on me? I hear a tongue, shriller than all the music, Cry 'Caesar!' Speak; Caesar is turn'd to hear.", 14)
Debug.Print ch
Debug.Print Caesar_Cipher(ch, -14)
End Sub

Function Caesar_Cipher(sText As String, lngNumber As Long) As String
Dim Tbl, strGlob As String, strTemp As String, i As Long, bytAscii As Byte
Const MAJ As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
Const NB_LETTERS As Byte = 26
Const DIFFASCIIMAJ As Byte = 65 - NB_LETTERS
Const DIFFASCIIMIN As Byte = 97 - NB_LETTERS

strTemp = sText
If lngNumber < NB_LETTERS And lngNumber > NB_LETTERS * -1 Then
strGlob = String(NB_LETTERS * 4, " ")
LSet strGlob = MAJ & MAJ & MAJ
Tbl = Split(StrConv(strGlob, vbUnicode), Chr(0))
For i = 1 To Len(strTemp)
If Mid(strTemp, i, 1) Like "[a-zA-Z]" Then
bytAscii = Asc(Mid(strTemp, i, 1))
If Mid(strTemp, i, 1) = Tbl(bytAscii - DIFFASCIIMAJ) Then
Mid(strTemp, i) = Tbl(bytAscii - DIFFASCIIMAJ + lngNumber)
Else
Mid(strTemp, i) = LCase(Tbl(bytAscii - DIFFASCIIMIN + lngNumber))
End If
End If
Next i
End If
Caesar_Cipher = strTemp
End Function```
Output:
```QOSGOF: Kvc wg wh wb hvs dfsgg hvoh qozzg cb as? W vsof o hcbuis, gvfwzzsf hvob ozz hvs aigwq, Qfm 'Qosgof!' Gdsoy; Qosgof wg hifb'r hc vsof.
CAESAR: Who is it in the press that calls on me? I hear a tongue, shriller than all the music, Cry 'Caesar!' Speak; Caesar is turn'd to hear.```

## VBScript

Note that a left rotation has an equivalent right rotation so all rotations are converted to the equivalent right rotation prior to translation.

```
str = "IT WAS THE BEST OF TIMES, IT WAS THE WORST OF TIMES."

Wscript.Echo str
Wscript.Echo Rotate(str,5)
Wscript.Echo Rotate(Rotate(str,5),-5)

'Rotate (Caesar encrypt/decrypt) test <numpos> positions.
'  numpos < 0 - rotate left
'  numpos > 0 - rotate right
'Left rotation is converted to equivalent right rotation

Function Rotate (text, numpos)

dim dic: set dic = CreateObject("Scripting.Dictionary")
dim ltr: ltr = Split("A B C D E F G H I J K L M N O P Q R S T U V W X Y Z")
dim rot: rot = (26 + numpos Mod 26) Mod 26 'convert all to right rotation
dim ch
dim i

for i = 0 to ubound(ltr)
dic(ltr(i)) = ltr((rot+i) Mod 26)
next

Rotate = ""

for i = 1 to Len(text)
ch = Mid(text,i,1)
if dic.Exists(ch) Then
Rotate = Rotate & dic(ch)
else
Rotate = Rotate & ch
end if
next

End Function```
Output:
```D:\script>Caesar.vbs
IT WAS THE BEST OF TIMES, IT WAS THE WORST OF TIMES.
NY BFX YMJ GJXY TK YNRJX, NY BFX YMJ BTWXY TK YNRJX.
IT WAS THE BEST OF TIMES, IT WAS THE WORST OF TIMES.
```

## Vedit macro language

This implementation ciphers/deciphers a highlighted block of text in-place in current edit buffer.

```#10 = Get_Num("Enter the key: positive to cipher, negative to de-cipher: ", STATLINE)

Goto_Pos(Block_Begin)
while(Cur_Pos < Block_End) {
#11 = Cur_Char & 0x60 + 1
if (Cur_Char >= 'A') {
Ins_Char((Cur_Char - #11 + 26 + #10) % 26 + #11, OVERWRITE)
} else {
Char(1)
}
}```
Output:

with key 13

```Original text:    Quick brown Fox jumps over the lazy Dog.
Encrypted text:   Dhvpx oebja Sbk whzcf bire gur ynml Qbt.
Decrypted text:   Quick brown Fox jumps over the lazy Dog.
```

## Visual Basic .NET

Translation of: C#
```Module Module1

Function Encrypt(ch As Char, code As Integer) As Char
If Not Char.IsLetter(ch) Then
Return ch
End If

Dim offset = AscW(If(Char.IsUpper(ch), "A"c, "a"c))
Dim test = (AscW(ch) + code - offset) Mod 26 + offset
Return ChrW(test)
End Function

Function Encrypt(input As String, code As Integer) As String
Return New String(input.Select(Function(ch) Encrypt(ch, code)).ToArray())
End Function

Function Decrypt(input As String, code As Integer) As String
Return Encrypt(input, 26 - code)
End Function

Sub Main()
Dim str = "Pack my box with five dozen liquor jugs."

Console.WriteLine(str)
str = Encrypt(str, 5)
Console.WriteLine("Encrypted: {0}", str)
str = Decrypt(str, 5)
Console.WriteLine("Decrypted: {0}", str)
End Sub

End Module```
Output:
```Pack my box with five dozen liquor jugs.
Encrypted: Ufhp rd gtc bnym knaj itejs qnvztw ozlx.
Decrypted: Pack my box with five dozen liquor jugs.```

## V (Vlang)

```import rand

const (
lo_abc = 'abcdefghijklmnopqrstuvwxyz'
up_abc = 'ABCDEFGHIJKLMNIPQRSTUVWXYZ'
)

fn main() {
key := rand.int_in_range(2, 25) or {13}
encrypted := caesar_encrypt('The five boxing wizards jump quickly', key)
println(encrypted)
println(caesar_decrypt(encrypted, key))
}

fn caesar_encrypt(str string, key int) string {
offset := key % 26
if offset == 0 {return str}
mut nchr := u8(0)
mut chr_arr := []u8{}
for chr in str {
if chr.ascii_str() in up_abc.split('') {
nchr = chr + u8(offset)
if nchr > u8(90) {nchr -= 26}
}
else if chr.ascii_str() in lo_abc.split('') {
nchr = chr + u8(offset)
if nchr > u8(122) {nchr -= 26}
}
else {nchr = chr}
chr_arr << nchr
}
return chr_arr.bytestr()
}

fn caesar_decrypt(str string, key int) string {
return caesar_encrypt(str, 26 - key)
}```
Output:
```Jxu vylu renydw mypqhti zkcf gkysabo
The five boxing wizards jump quickly
```

## Wortel

```@let {
; this function only replaces letters and keeps case
ceasar &[s n] !!s.replace &"[a-z]"gi &[x] [
@vars {
t x.charCodeAt.
l ?{
&& > t 96 < t 123 97
&& > t 64 < t 91 65
0
}
}
!String.fromCharCode ?{
l +l ~% 26 -+ n t l
t
}
]
!!ceasar "abc \$%^ ABC" 10
}```

Returns:

`"klm \$%^ KLM"`

## Wren

Translation of: Kotlin
```class Caesar {
static encrypt(s, key) {
var offset = key % 26
if (offset == 0) return s
var chars = List.filled(s.count, 0)
for (i in 0...s.count) {
var c = s[i].bytes[0]
var d = c
if (c >= 65 && c <= 90) { // 'A' to 'Z'
d = c + offset
if (d > 90) d = d - 26
} else if (c >= 97 && c <= 122) {  // 'a' to 'z'
d = c + offset
if (d > 122) d = d - 26
}
chars[i] = d
}
return chars.reduce("") { |acc, c| acc + String.fromByte(c) }
}

static decrypt(s, key) { encrypt(s, 26 - key) }
}

var encoded = Caesar.encrypt("Bright vixens jump; dozy fowl quack.", 8)
System.print(encoded)
System.print(Caesar.decrypt(encoded, 8))```
Output:
```Jzqopb dqfmva rcux; lwhg nwet yciks.
Bright vixens jump; dozy fowl quack.
```

## X86 Assembly

Translation of: C custom implementation
Works with: GCC version 7.3.0 - Ubuntu 18.04 64-bit
```                                        # Author: Ettore Forigo - Hexwell

.intel_syntax noprefix

.text
.globl main
main:
.PROLOGUE:
push    rbp
mov rbp, rsp
sub rsp, 32
mov QWORD PTR [rbp-32], rsi         # argv

.BODY:
mov BYTE PTR [rbp-1], 0             # shift = 0

.I_LOOP_INIT:
mov BYTE PTR [rbp-2], 0         # i = 0
jmp .I_LOOP_CONDITION           # I_LOOP_CONDITION
.I_LOOP_BODY:
movzx edx, BYTE PTR[rbp-1]      # shift
mov eax, edx                    # shift
sal eax, 2                      # shift << 2 == i * 4
add eax, edx                    # shift * 4 + shift = shift * 5
add eax, eax                    # shift * 5 + shift * 5 = shift * 10
mov ecx, eax                    # shift * 10
mov rax, QWORD PTR [rbp-32]     # argv
add rax, 8                      # argv + 1
mov rdx, QWORD PTR [rax]        # argv[1]
movzx eax, BYTE PTR [rbp-2]     # i
add rax, rdx                    # argv[1] + i
movzx eax, BYTE PTR [rax]       # argv[1][i]
add eax, ecx                    # shift * 10 + argv[1][i]
sub eax, 48                     # shift * 10 + argv[1][i] - '0'
mov BYTE PTR [rbp-1], al        # shift = shift * 10 + argv[1][i] - '0'
.I_LOOP_INCREMENT:
movzx eax, BYTE PTR [rbp-2]     # i
add eax, 1                      # i + 1
mov BYTE PTR [rbp-2], al        # i++
.I_LOOP_CONDITION:
mov rax, QWORD PTR [rbp-32]     # argv
add rax, 8                      # argv + 1
mov rax, QWORD PTR [rax]        # argv[1]
movzx edx, BYTE PTR [rbp-2]     # i
add rax, rdx                    # argv[1] + i
movzx rax, BYTE PTR [rax]       # argv[1][i]
test al, al                     # argv[1][i]?
jne .I_LOOP_BODY                # I_LOOP_BODY

.CAESAR_LOOP_INIT:
mov BYTE PTR [rbp-2], 0         # i = 0
jmp .CAESAR_LOOP_CONDITION      # CAESAR_LOOP_CONDITION
.CAESAR_LOOP_BODY:
mov rax, QWORD PTR [rbp-32]     # argv
add rax, 16                     # argv + 2
mov rdx, QWORD PTR [rax]        # argv[2]
movzx eax, BYTE PTR [rbp-2]     # i
add rax, rdx                    # argv[2] + i
mov rbx, rax                    # argv[2] + i
movzx eax, BYTE PTR [rax]       # argv[2][i]
cmp al, 32                      # argv[2][i] == ' '
je .CAESAR_LOOP_INCREMENT       # CAESAR_LOOP_INCREMENT
movzx edx, BYTE PTR [rbx]       # argv[2][i]
mov ecx, edx                    # argv[2][i]
movzx edx, BYTE PTR [rbp-1]     # shift
add edx, ecx                    # argv[2][i] + shift
sub edx, 97                     # argv[2][i] + shift - 'a'
mov BYTE PTR [rbx], dl          # argv[2][i] = argv[2][i] + shift - 'a'
movzx eax, BYTE PTR [rbx]       # argv[2][i]
cmp al, 25                      # argv[2][i] <=> 25
jle .CAESAR_RESTORE_ASCII       # <= CAESAR_RESTORE_ASCII
movzx edx, BYTE PTR [rbx]       # argv[2][i]
sub edx, 26                     # argv[2][i] - 26
mov BYTE PTR [rbx], dl          # argv[2][i] = argv[2][i] - 26
.CAESAR_RESTORE_ASCII:
movzx edx, BYTE PTR [rbx]       # argv[2][i]
add edx, 97                     # argv[2][i] + 'a'
mov BYTE PTR [rbx], dl          # argv[2][i] = argv[2][i] + 'a'
.CAESAR_LOOP_INCREMENT:
movzx eax, BYTE PTR [rbp-2]     # i
add eax, 1                      # i + 1
mov BYTE PTR [rbp-2], al        # i++
.CAESAR_LOOP_CONDITION:
mov rax, QWORD PTR [rbp-32]     # argv
add rax, 16                     # argv + 2
mov rdx, QWORD PTR [rax]        # argv[2]
movzx eax, BYTE PTR [rbp-2]     # i
add rax, rdx                    # argv[2] + i
movzx eax, BYTE PTR [rax]       # argv[2][i]
test al, al                     # argv[2][i]?
jne .CAESAR_LOOP_BODY           # CAESAR_LOOP_BODY

mov rax, QWORD PTR [rbp-32]         # argv
add rax, 16                         # argv + 2
mov rax, QWORD PTR [rax]            # argv[2]
mov rdi, rax                        # argv[2]
call    puts                        # puts(argv[2])

.RETURN:
mov eax, 0                          # 0
leave
ret                                 # return 0```

Usage:

```\$ gcc caesar.S -o caesar
\$ ./caesar 10 abc
klm
\$ ./caesar 16 klm
abc```

## XBasic

Translation of: Modula-2
Works with: Windows XBasic
```PROGRAM "caesarcipher"
VERSION "0.0001"

DECLARE FUNCTION Entry()
INTERNAL FUNCTION Encrypt\$(p\$, key%%)
INTERNAL FUNCTION Decrypt\$(p\$, key%%)

FUNCTION Entry()
txt\$ = "The five boxing wizards jump quickly"
key%% = 3
PRINT "Original:  "; txt\$
enc\$ = Encrypt\$(txt\$, key%%)
PRINT "Encrypted: "; enc\$
PRINT "Decrypted: "; Decrypt\$(enc\$, key%%)
END FUNCTION

FUNCTION Encrypt\$(p\$, key%%)
e\$ = p\$ ' In order to avoid iterative concatenations
FOR i = 0 TO LEN(p\$) - 1
t@@ = p\${i} ' or (slower) t@@ = ASC(p\$, i + 1)
SELECT CASE TRUE
CASE (t@@ >= 'A') AND (t@@ <= 'Z'):
t@@ = t@@ + key@@
IF t&& > 'Z' THEN
t@@ = t@@ - 26
END IF
CASE (t@@ >= 'a') AND (t@@ <= 'z'):
t@@ = t@@ + key%%
IF t@@ > 'z' THEN
t@@ = t@@ - 26
END IF
END SELECT
e\${i} = t@@
NEXT i
END FUNCTION e\$

FUNCTION Decrypt\$(p\$, key%%)
e\$ = p\$ ' In order to avoid iterative concatenations
FOR i = 0 TO LEN(p\$) - 1
t@@ = p\${i} ' or (slower) t@@ = ASC(p\$, i + 1)
SELECT CASE TRUE
CASE (t@@ >= 'A') AND (t@@ <= 'Z'):
t@@ = t@@ - key%%
IF t@@ < 'A' THEN
t@@ = t@@ + 26
END IF
CASE (t@@ >= 'a') AND (t@@ <= 'z'):
t@@ = t@@ - key%%
IF t@@ < 'a' THEN
t@@ = t@@ + 26
END IF
END SELECT
e\${i} = t@@
NEXT i
END FUNCTION e\$
END PROGRAM```
Output:
```Original:  The five boxing wizards jump quickly
Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted: The five boxing wizards jump quickly
```

## XBS

```set letters="ABCDEFGHIJKLMNOPQRSTUVWXYZ"::split();

func caesar(text,shift:number=1){
set res:string="";
for(i=0;?text-1;1){
set t=text::at(i);
set n=(letters::find(t::upper())+shift)%?letters;
while(n<0){
n=?letters+n;
}
set l=letters[n];
(t::upper()==t)|=>l=l::lower()
res+=l;
}
send res;
}

func decode(text,shift:number=1){
set res:string="";
for(i=0;?text-1;1){
set t=text::at(i);
set n=(letters::find(t::upper())-shift)%?letters;
while(n<0){
n=?letters+n;
}
set l=letters[n];
(t::upper()==t)|=>l=l::lower()
res+=l;
}
send res;
}

set e=caesar("Hi",20);
set d=decode(e,20);

log(e);
log(d);```
Output:
```Bc
Hi
```

## XLISP

```(defun caesar-encode (text key)
(defun encode (ascii-code)
(defun rotate (character alphabet)
(define code (+ character key))
(cond
((> code (+ alphabet 25)) (- code 26))
((< code alphabet) (+ code 26))
(t code)))
(cond
((and (>= ascii-code 65) (<= ascii-code 90)) (rotate ascii-code 65))
((and (>= ascii-code 97) (<= ascii-code 122)) (rotate ascii-code 97))
(t ascii-code)))
(list->string (mapcar integer->char (mapcar encode (mapcar char->integer (string->list text))))))

(defun caesar-decode (text key)
(caesar-encode text (- 26 key)))```

Test it in a REPL:

```[1] (define caesar-test (caesar-encode "CAESAR: Who is it in the press that calls on me? I hear a tongue, shriller than all the music, Cry 'Caesar!' Speak; Caesar is turn'd to hear." 14))

CAESAR-TEST
[2] caesar-test

"QOSGOF: Kvc wg wh wb hvs dfsgg hvoh qozzg cb as? W vsof o hcbuis, gvfwzzsf hvob ozz hvs aigwq, Qfm 'Qosgof!' Gdsoy; Qosgof wg hifb'r hc vsof."
[3] (caesar-decode caesar-test 14)

"CAESAR: Who is it in the press that calls on me? I hear a tongue, shriller than all the music, Cry 'Caesar!' Speak; Caesar is turn'd to hear."```

## XPL0

To decrypt a message use the negative value of the encrypting key. Usage: caesar key <infile.txt >outfile.xxx

```code ChIn=7, ChOut=8, IntIn=10;
int  Key, C;
[Key:= IntIn(8);
repeat  C:= ChIn(1);
if C>=^a & C<=^z then C:= C-\$20;
if C>=^A & C<=^Z then
[C:= C+Key;
if C>^Z then C:= C-26
else if C<^A then C:= C+26;
];
ChOut(0, C);
until   C=\$1A; \EOF
]```

Example outfile.xxx:

```SDFN PB ERA ZLWK ILYH GRCHQ OLTXRU MXJV.
```

## Yabasic

```REM *** By changing the key and pattern, an encryption system that is difficult to break can be achieved. ***

text\$ = "You are encouraged to solve this task according to the task description, using any language you may know."
key\$ = "desoxirribonucleic acid" // With a single character you get a Caesar encryption. With more characters the key is much more difficult to discover.
CIPHER = 1 : DECIPHER = -1

print text\$ : print
encrypted\$ = criptex\$(text\$, key\$, CIPHER)
a = open("cryptedText.txt", "w") : if a then print #a encrypted\$ : close #a end if
print encrypted\$ : print
print criptex\$(encrypted\$, key\$, DECIPHER)

sub criptex\$(text\$, key\$, mode)
local i, k, delta, longtext, longPattern, longkey, pattern\$, res\$

pattern\$ = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890 .,;:()-"

longPattern = len(pattern\$)
longtext = len(text\$)
longkey = len(key\$)

for i = 1 to longtext
k = k + 1 : if k > longkey k = 1
delta = instr(pattern\$, mid\$(text\$, i, 1))
delta = delta + (mode * instr(pattern\$, mid\$(key\$, k, 1)))
if delta > longPattern then
delta = delta - longPattern
elseif delta < 1 then
delta = longPattern + delta
end if
res\$ = res\$ + mid\$(pattern\$, delta, 1)
next i

return res\$
end sub```
Output:
```You are encouraged to solve this task according to the task description, using any language you may know.

3tNhyAwknprCPumlng4urbwsqOtqCzAB,IoNneflfhsgrrk(MDqCzwbvpGF;pjBfkjsCmssnhSBAFp,pBT;xfwjnbjn:CtNhKjQktpDKo

You are encouraged to solve this task according to the task description, using any language you may know.```

## Zig

```const std = @import("std");
const stdout = @import("std").io.getStdOut().writer();

pub fn rot(txt: []u8, key: u8) void {
for (txt, 0..txt.len) |c, i| {
if (std.ascii.isLower(c)) {
txt[i] = (c - 'a' + key) % 26 + 'a';
} else if (std.ascii.isUpper(c)) {
txt[i] = (c - 'A' + key) % 26 + 'A';
}
}
}

pub fn main() !void {
const key = 3;
var txt = "The five boxing wizards jump quickly".*;

try stdout.print("Original:  {s}\n", .{txt});
rot(&txt, key);
try stdout.print("Encrypted: {s}\n", .{txt});
rot(&txt, 26 - key);
try stdout.print("Decrypted: {s}\n", .{txt});
}```
Output:
```Original:  The five boxing wizards jump quickly
Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob
Decrypted: The five boxing wizards jump quickly
```

## zkl

```fcn caesarCodec(str,n,encode=True){
var [const] letters=["a".."z"].chain(["A".."Z"]).pump(String);  // static
if(not encode) n=26 - n;
m,sz := n + 26, 26 - n;
ltrs:=String(letters[n,sz],letters[0,n],letters[m,sz],letters[26,n]);
str.translate(letters,ltrs)
}```
```text:="The five boxing wizards jump quickly";
N:=3;
code:=caesarCodec(text,N);
println("text = ",text);
println("encoded(%d) = %s".fmt(N,code));
println("decoded = ",caesarCodec(code,N,False));```
Output:
```text = The five boxing wizards jump quickly
encoded(3) = Wkh ilyh eralqj zlcdugv mxps txlfnob
decoded = The five boxing wizards jump quickly
```

## zonnon

```module Caesar;
const
size = 25;

type
Operation = (code,decode);

procedure C_D(s:string;k:integer;op: Operation): string;
var
i,key: integer;
resp: string;
n,c: char;
begin
resp := "";
if op = Operation.decode then key := k else key := (26 - k) end;
for i := 0 to len(s) - 1 do
c := cap(s[i]);
if (c >= 'A') & (c <= 'Z') then
resp := resp +
string(char(integer('A') + ((integer(c) - integer('A') + key )) mod 26));
else
resp := resp + string(c)
end;
end;
return  resp
end C_D;

procedure {public} Cipher(s:string;k:integer):string;
var
i: integer;
resp: string;
n,c: char;
begin
return C_D(s,k,Operation.code)
end Cipher;

procedure {public} Decipher(s:string;k:integer):string;
var
i: integer;
resp: string;
n,c: char;
begin
return C_D(s,k,Operation.decode)
end Decipher;

var
txt,cipher,decipher: string;

begin
txt := "HI";cipher := Caesar.Cipher(txt,2);decipher := Caesar.Decipher(cipher,2);
writeln(txt," -c-> ",cipher," -d-> ",decipher);
txt := "ZA";cipher := Caesar.Cipher(txt,2);decipher := Caesar.Decipher(cipher,2);
writeln(txt," -c-> ",cipher," -d-> ",decipher);
txt := "The five boxing wizards jump quickly";
cipher := Caesar.Cipher(txt,2);decipher := Caesar.Decipher(cipher,2);
writeln(txt," -c-> ",cipher," -d-> ",decipher)
end Caesar.```
Output:
```  HI -c->   FG -d->   HI
ZA -c->   XY -d->   ZA
The five boxing wizards jump quickly -c-> RFC DGTC ZMVGLE UGXYPBQ HSKN OSGAIJW -d-> THE FIVE BOXING WIZARDS JUMP QUICKLY
```

## ZX Spectrum Basic

Translation of: BBC BASIC
```10 LET t\$="PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS"
20 PRINT t\$''
30 LET key=RND*25+1
40 LET k=key: GO SUB 1000: PRINT t\$''
50 LET k=26-key: GO SUB 1000: PRINT t\$
60 STOP
1000 FOR i=1 TO LEN t\$
1010 LET c= CODE t\$(i)
1020 IF c<65 OR c>90 THEN GO TO 1050
1030 LET c=c+k: IF c>90 THEN LET c=c-90+64
1040 LET t\$(i)=CHR\$ c
1050 NEXT i
1060 RETURN```
Translation of: Yabasic
```10 LET t\$="Wonderful ZX Spectrum."
20 LET c\$="a":REM more characters, more difficult for decript
30 LET CIFRA=1: LET DESCIFRA=-1
40 PRINT t\$''
50 LET modo=CIFRA: GO SUB 1000
60 PRINT r\$''
70 LET t\$=r\$: LET modo=DESCIFRA: GO SUB 1000
80 PRINT r\$''
90 STOP
1000 REM Criptex
1010 LET p\$="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890 .,;:()-"
1020 LET longPatron=LEN p\$
1030 LET longTexto=LEN t\$
1040 LET longClave=LEN c\$
1045 LET k=0: LET r\$=""
1050 FOR i=1 TO longTexto
1060 LET k=k+1: IF k>longClave THEN LET k=1
1070 LET x\$=t\$(i)
1080 FOR j=1 TO longPatron
1090 IF x\$=p\$(j) THEN LET delta=j: GO TO 1110
1100 NEXT j
1110 LET x\$=c\$(k)
1120 FOR j=1 TO longPatron
1130 IF x\$=p\$(j) THEN LET delta=delta+modo*j: GO TO 1150
1140 NEXT j
1150 IF delta>longPatron THEN LET delta=delta-longPatron: GO TO 1170
1160 IF delta<1 THEN LET delta=longPatron+delta
1170 LET r\$=r\$+p\$(delta)
1180 NEXT i
1190 RETURN```