Vigenère cipher: Difference between revisions

</pre>

=={{header|Action!}}==

<lang Action!>PROC Fix(CHAR ARRAY in,fixed)

INT i

CHAR c

fixed(0)=0

FOR i=1 TO in(0)

DO

c=in(i)

IF c>='a AND c<='z THEN

c==-('a-'A)

FI

IF c>='A AND c<='Z THEN

fixed(0)==+1

fixed(fixed(0))=c

FI

OD

RETURN

PROC Process(CHAR ARRAY in,key,out INT dir)

CHAR ARRAY inFixed(256),keyFixed(256)

INT keyI,tmp,i

CHAR c

out(0)=0

Fix(in,inFixed)

Fix(key,keyFixed)

IF inFixed(0)=0 OR keyFixed(0)=0 THEN

RETURN

FI

keyI=1

FOR i=1 TO inFixed(0)

DO

c=inFixed(i)

tmp=c-'A+dir*(keyFixed(keyI)-'A)

IF tmp<0 THEN

tmp==+26

FI

out(0)==+1

out(out(0))='A+tmp MOD 26

keyI==+1

IF keyI>keyFixed(0) THEN

keyI=1

FI

OD

RETURN

PROC Encrypt(CHAR ARRAY in,key,out)

Process(in,key,out,1)

RETURN

PROC Decrypt(CHAR ARRAY in,key,out)

Process(in,key,out,-1)

RETURN

PROC Test(CHAR ARRAY in,key)

CHAR ARRAY enc(256),dec(256)

PrintE("Original:") PrintE(in)

Encrypt(in,key,enc)

PrintF("Encrypted key=%S:%E",key) PrintE(enc)

Decrypt(enc,key,dec)

PrintF("Decrypted key=%S:%E",key) PrintE(dec)

PutE()

RETURN

PROC Main()

Test("Attack at dawn!","LEMONLEMONLE")

Test("Crypto is short for cryptography.","ABCDABCDABCDABCDABCDABCDABCD")

RETURN</lang>

{{out}}

[https://gitlab.com/amarok8bit/action-rosetta-code/-/raw/master/images/Vigen%C3%A8re_cipher.png Screenshot from Atari 8-bit computer]

<pre>

Original:

Attack at dawn!

Encrypted key=LEMONLEMONLE:

LXFOPVEFRNHR

Decrypted key=LEMONLEMONLE:

ATTACKATDAWN

Original:

Crypto is short for cryptography.

Encrypted key=ABCDABCDABCDABCDABCDABCDABCD:

CSASTPKVSIQUTGQUCSASTPIUAQJB

Decrypted key=ABCDABCDABCDABCDABCDABCDABCD:

CRYPTOISSHORTFORCRYPTOGRAPHY