Straddling checkerboard
You are encouraged to solve this task according to the task description, using any language you may know.
- Task
Implement functions to encrypt and decrypt a message using the straddling checkerboard method. The checkerboard should take a 28 character alphabet (A-Z plus a full stop and an escape character) and two different numbers representing the blanks in the first row. The output will be a series of decimal digits.
Numbers should be encrypted by inserting the escape character before each digit, then including the digit unencrypted. This should be reversed for decryption.
11l
V t = [[String(‘79’), ‘0’, ‘1’, ‘2’, ‘3’, ‘4’, ‘5’, ‘6’, ‘7’, ‘8’, ‘9’],
[String(‘’), ‘H’, ‘O’, ‘L’, ‘’, ‘M’, ‘E’, ‘S’, ‘’, ‘R’, ‘T’],
[String(‘3’), ‘A’, ‘B’, ‘C’, ‘D’, ‘F’, ‘G’, ‘I’, ‘J’, ‘K’, ‘N’],
[String(‘7’), ‘P’, ‘Q’, ‘U’, ‘V’, ‘W’, ‘X’, ‘Y’, ‘Z’, ‘.’, ‘/’]]
F straddle(s)
R multiloop_filtered(Array(s.uppercase()), :t, (c, l) -> c C l, (c, l) -> l[0]‘’:t[0][l.index(c)]).join(‘’)
F unstraddle(s)
[String] r
V si = 0
F next()
R @s[@si++]
L
I si == s.len
L.break
V c = s[si++]
I c C (:t[2][0], :t[3][0])
V i = [:t[2][0], :t[3][0]].index(c)
V n = :t[2 + i][:t[0].index(next())]
r [+]= I n == ‘/’ {next()} E n
E
r [+]= :t[1][:t[0].index(c)]
R r
V O = ‘One night-it was on the twentieth of March, 1888-I was returning’
print(‘Encoded: ’straddle(O))
print(‘Decoded: ’unstraddle(straddle(O)).join(‘’))- Output:
Encoded: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
ALGOL 68
Note: This specimen retains the original C++ coding style.
#!/usr/local/bin/a68g --script #
PRIO MIN=5, MAX=5;
OP MIN = (INT a, b)INT: (a<b|a|b),
MAX = (INT a, b)INT: (a>b|a|b);
MODE STRADDLINGCHECKERBOARD=STRUCT(
[0:9]CHAR first, second, third,
[ABS ".": ABS "Z"]STRING table,
INT row u, row v,
CHAR esc, skip
);
STRUCT(
PROC (REF STRADDLINGCHECKERBOARD #self#, STRING #alphabet#, INT #u#, INT #v#)VOID init,
PROC (REF STRADDLINGCHECKERBOARD #self#, STRING #plain#)STRING encode,
PROC (REF STRADDLINGCHECKERBOARD #self#, STRING #plain#)STRING decode
) sc class = (
# PROC init = # (REF STRADDLINGCHECKERBOARD self, STRING in alphabet, INT u, v)VOID:
(
STRING alphabet = in alphabet[@0];
esc OF self := alphabet[UPB alphabet]; # use the last CHAR as the escape #
skip OF self := alphabet[UPB alphabet-1];
row u OF self := u MIN v;
row v OF self := u MAX v;
OP DIGIT = (INT i)CHAR: REPR(ABS "0" + i );
INT j := LWB alphabet;
# (first OF self)[u] := (first OF self)[v] := skip; #
FOR i FROM LWB first OF self TO UPB first OF self DO
IF i NE u AND i NE v THEN
(first OF self)[i] := alphabet[j];
(table OF self)[ABS alphabet[j]] := DIGIT i;
j+:=1
FI;
(second OF self)[i] := alphabet[i+8];
(table OF self)[ABS alphabet[i+8]] := DIGIT (row u OF self) + DIGIT i;
(third OF self)[i] := alphabet[i+18];
(table OF self)[ABS alphabet[i+18]] := DIGIT (row v OF self) + DIGIT i
OD
),
# PROC encode = # (REF STRADDLINGCHECKERBOARD self, STRING plain)STRING:
(
STRING esc = (table OF self)[ABS (esc OF self)];
INT l2u = ABS "A" - ABS "a";
STRING out := "";
FOR i FROM LWB plain TO UPB plain DO
CHAR c := plain[i];
IF "a" <= c AND c <= "z" THEN
c := REPR ( ABS c + l2u) FI;
IF "A" <= c AND c <= "Z" THEN
out +:= (table OF self)[ABS c]
ELIF "0" <= c AND c <= "9" THEN
out +:= esc + c
FI
OD;
out # EXIT #
),
# PROC decode = # (REF STRADDLINGCHECKERBOARD self, STRING cipher)STRING:
(
CHAR null = REPR 0;
STRING out;
INT state := 0;
FOR i FROM LWB cipher TO UPB cipher DO
INT n := ABS cipher[i] - ABS "0";
CHAR next :=
CASE state IN
#1:# (second OF self)[n],
#2:# (third OF self)[n],
#3:# cipher[i]
OUT
IF n = row u OF self THEN
state := 1; null
ELIF n = row v OF self THEN
state := 2; null
ELSE
(first OF self)[n]
FI
ESAC;
IF next = "/" THEN
state := 3
ELIF next NE null THEN
state := 0;
out +:= next
FI
OD;
out # EXIT #
)
);
main:
(
STRADDLINGCHECKERBOARD sc; (init OF sc class)(sc, "HOLMESRTABCDFGIJKNPQUVWXYZ./", 3, 7);
STRING original := "One night-it was on the twentieth of March, 1888-I was returning"[@0];
STRING en := (encode OF sc class)(sc, original);
STRING de := (decode OF sc class)(sc, en);
printf(($ggl$,
"Original: ", original,
"Encoded: ", en,
"Decoded: ", de
))
)Output:
Original: One night-it was on the twentieth of March, 1888-I was returning Encoded: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
AutoHotkey
board := "
(
ET AON RIS
BCDFGHJKLM
PQ/UVWXYZ.
)"
Text = One night-it was on the twentieth of March, 1888-I was returning
StringUpper, Text, Text
Text := RegExReplace(text, "[^A-Z0-9]")
Num2 := InStr(board, A_Space) -1
Num3 := InStr(board, A_Space, true, Num1+1) -1
Loop Parse, Text
{
char := A_LoopField
Loop Parse, board, `n
{
If (Pos := InStr(A_LoopField, char))
out .= Num%A_Index% . Pos-1
else if (Pos := InStr(A_LoopField, "/")) && InStr("0123456789", char)
out .= Num%A_Index% . Pos-1 . char
}
}
MsgBox % out
i := 0
While (LoopField := SubStr(out, ++i, 1)) <> ""
{
If (LoopField = num2) or (LoopField = num3)
col := SubStr(out, ++i, 1)
else col := 0
Loop Parse, board, `n
{
If !col && A_Index = 1
dec .= SubStr(A_LoopField, LoopField+1, 1)
Else If (Num%A_Index% = LoopField) && col
dec .= SubStr(A_LoopField, col+1, 1)
If SubStr(dec, 0) = "/"
dec := SubStr(dec, 1, StrLen(dec)-1) . SubStr(out, ++i, 1)
}
}
MsgBox % dec
C
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <ctype.h>
#include <glib.h>
#define ROWS 4
#define COLS 10
#define NPRX "/"
/* wikipedia table
const char *table[ROWS][COLS] =
{
{ "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" },
{ "E", "T", NULL, "A", "O", "N", NULL, "R", "I", "S },
{ "B", "C", "D", "F", "G", "H", "J", "K", "L", "M" },
{ "P", "Q", NPRX, "U", "V", "W", "X", "Y", "Z", "." }
};
*/
/* example of extending the table, COLS must be 11
const char *table[ROWS][COLS] =
{
{ "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", ":" },
{ "H", "O", "L", NULL, "M", "E", "S", NULL, "R", "T", "," },
{ "A", "B", "C", "D", "F", "G", "I", "J", "K", "N", "-" },
{ "P", "Q", "U", "V", "W", "X", "Y", "Z", ".", NPRX, "?" }
};
*/
// task table
const char *table[ROWS][COLS] =
{
{ "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" },
{ "H", "O", "L", NULL, "M", "E", "S", NULL, "R", "T" },
{ "A", "B", "C", "D", "F", "G", "I", "J", "K", "N" },
{ "P", "Q", "U", "V", "W", "X", "Y", "Z", ".", NPRX }
};
GHashTable *create_table_from_array(const char *table[ROWS][COLS], bool is_encoding)
{
char buf[16];
GHashTable *r = g_hash_table_new_full(g_str_hash, g_str_equal, free, free);
size_t i, j, k, m;
for(i = 0, m = 0; i < COLS; i++)
{
if (table[1][i] == NULL) m++;
}
const size_t SELNUM = m;
size_t selectors[SELNUM];
size_t numprefix_row, numprefix_col;
bool has_numprefix = false;
// selectors keep the indexes of the symbols to select 2nd and 3rd real row;
// nulls must be placed into the 2nd row of the table
for(i = 0, k = 0; i < COLS && k < SELNUM; i++)
{
if ( table[1][i] == NULL )
{
selectors[k] = i;
k++;
}
}
// numprefix is the prefix to insert symbols from the 1st row of table (numbers)
for(j = 1; j < ROWS; j++)
{
for(i = 0; i < COLS; i++)
{
if (table[j][i] == NULL) continue;
if ( strcmp(table[j][i], NPRX) == 0 )
{
numprefix_col = i;
numprefix_row = j;
has_numprefix = true;
break;
}
}
}
// create the map for each symbol
for(i = has_numprefix ? 0 : 1; i < ROWS; i++)
{
for(j = 0; j < COLS; j++)
{
if (table[i][j] == NULL) continue;
if (strlen(table[i][j]) > 1)
{
fprintf(stderr, "symbols must be 1 byte long\n");
continue; // we continue just ignoring the issue
}
if (has_numprefix && i == (ROWS-1) && j == numprefix_col && i == numprefix_row) continue;
if (has_numprefix && i == 0)
{
snprintf(buf, sizeof(buf), "%s%s%s", table[0][selectors[SELNUM-1]], table[0][numprefix_col], table[0][j]);
}
else if (i == 1)
{
snprintf(buf, sizeof(buf), "%s", table[0][j]);
}
else
{
snprintf(buf, sizeof(buf), "%s%s", table[0][selectors[i-2]], table[0][j]);
}
if (is_encoding) g_hash_table_insert(r, strdup(table[i][j]), strdup(buf));
else g_hash_table_insert(r, strdup(buf), strdup(table[i][j]));
}
}
if (is_encoding) g_hash_table_insert(r, strdup("mode"), strdup("encode"));
else g_hash_table_insert(r, strdup("mode"), strdup("decode"));
return r;
}
char *decode(GHashTable *et, const char *enctext)
{
char *r = NULL;
if (et == NULL || enctext == NULL || strlen(enctext) == 0 ||
g_hash_table_lookup(et, "mode") == NULL ||
strcmp(g_hash_table_lookup(et, "mode"), "decode") != 0) return NULL;
GString *res = g_string_new(NULL);
GString *en = g_string_new(NULL);
for( ; *enctext != '\0'; enctext++ )
{
if (en->len < 3)
{
g_string_append_c(en, *enctext);
r = g_hash_table_lookup(et, en->str);
if (r == NULL) continue;
g_string_append(res, r);
g_string_truncate(en, 0);
}
else
{
fprintf(stderr, "decoding error\n");
break;
}
}
r = res->str;
g_string_free(res, FALSE);
g_string_free(en, TRUE);
return r;
}
char *encode(GHashTable *et, const char *plaintext, int (*trasf)(int), bool compress_spaces)
{
GString *s;
char *r = NULL;
char buf[2] = { 0 };
if (plaintext == NULL ||
et == NULL || g_hash_table_lookup(et, "mode") == NULL ||
strcmp(g_hash_table_lookup(et, "mode"), "encode") != 0) return NULL;
s = g_string_new(NULL);
for(buf[0] = trasf ? trasf(*plaintext) : *plaintext;
buf[0] != '\0';
buf[0] = trasf ? trasf(*++plaintext) : *++plaintext)
{
if ( (r = g_hash_table_lookup(et, buf)) != NULL )
{
g_string_append(s, r);
}
else if (isspace(buf[0]))
{
if (!compress_spaces) g_string_append(s, buf);
}
else
{
fprintf(stderr, "char '%s' is not encodable%s\n",
isprint(buf[0]) ? buf : "?",
!compress_spaces ? ", replacing with a space" : "");
if (!compress_spaces) g_string_append_c(s, ' ');
}
}
r = s->str;
g_string_free(s, FALSE);
return r;
}
int main()
{
GHashTable *enctab = create_table_from_array(table, true); // is encoding? true
GHashTable *dectab = create_table_from_array(table, false); // is encoding? false (decoding)
const char *text = "One night-it was on the twentieth of March, 1888-I was returning";
char *encoded = encode(enctab, text, toupper, true);
printf("%s\n", encoded);
char *decoded = decode(dectab, encoded);
printf("%s\n", decoded);
free(decoded);
free(encoded);
g_hash_table_destroy(enctab);
g_hash_table_destroy(dectab);
return 0;
}
Shorter version
#include <stdio.h>
#include <stdlib.h>
const char * board = "ET AON RIS"
"BCDFGHJKLM"
"PQ/UVWXYZ.";
char encode[128] = {0};
char decode[128] = {0};
int row[2] = {0};
void read_table(const char *s)
{
int i, code;
for (i = 0; i < 30; i++) {
if (s[i] == '\0') {
fprintf(stderr, "Table too short\n");
exit(1);
}
if (s[i] == ' ') {
row[ row[0] ? 1 : 0 ] = i;
continue;
}
code = ((i < 10) ? 0 : i < 20 ? row[0] : row[1])
* 10 + (i % 10);
encode[0 + s[i]] = code; /* guess what 0 + s[i] does, sigh */
decode[code] = s[i];
}
}
void encipher(const char *in, char *out, int strip)
{
#define PUTCODE(c) { if (c > 9) {*(out++) = c / 10 + '0'; c %= 10;} *(out++) = c + '0'; }
int c, code;
while ((c = *(in++)) != '\0') {
if (c >= '0' && c <= '9') {
code = encode['.'];
c -= '0';
PUTCODE(code);
PUTCODE(c);
continue;
}
c &= ~0x20;
if (c >= 'A' && c <= 'Z') code = encode[c];
else if (strip && !c ) continue;
else code = encode['/'];
PUTCODE(code);
}
*(out++) = '\0';
}
void decipher(const char *in, char *out, int strip)
{
int c;
while ((c = *(in++)) != '\0') {
c -= '0';
if (c == row[0] || c == row[1])
c = c * 10 + *(in++) - '0';
c = decode[c];
if (c == '.') c = *(in++);
if (c == '/' && !strip) c = ' ';
*(out++) = c;
}
*(out++) = '\0';
}
int main()
{
const char *msg = "In the winter 1965/we were hungry/just barely alive";
char enc[100] = {0}, dec[100] = {0};
read_table(board);
printf("message: %s\n", msg);
encipher(msg, enc, 0); printf("encoded: %s\n", enc);
decipher(enc, dec, 0); printf("decoded: %s\n", dec);
printf("\nNo spaces:\n");
encipher(msg, enc, 1); printf("encoded: %s\n", enc);
decipher(enc, dec, 1); printf("decoded: %s\n", dec);
return 0;
}
Output:
message: In the winter 1965/we were hungry/just barely alive
encoded: 85621250626585107626916996966956265062650706225635247676226639162203702867623288640
decoded: IN THE WINTER 1965 WE WERE HUNGRY JUST BARELY ALIVE
No spaces:
encoded: 851250658510769169969669562650650702563524767622663912037028673288640
decoded: INTHEWINTER1965/WEWEREHUNGRY/JUSTBARELYALIVE
C#
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
namespace StraddlingCheckerboard
{
class Program
{
public readonly static IReadOnlyDictionary<char, string> val2Key;
public readonly static IReadOnlyDictionary<string, char> key2Val;
static Program()
{
val2Key = new Dictionary<char, string> {
{'A',"30"}, {'B',"31"}, {'C',"32"}, {'D',"33"}, {'E',"5"}, {'F',"34"}, {'G',"35"},
{'H',"0"}, {'I',"36"}, {'J',"37"}, {'K',"38"}, {'L',"2"}, {'M',"4"}, {'.',"78"},
{'N',"39"}, {'/',"79"}, {'O',"1"}, {'0',"790"}, {'P',"70"}, {'1',"791"}, {'Q',"71"},
{'2',"792"}, {'R',"8"}, {'3',"793"}, {'S',"6"}, {'4',"794"}, {'T',"9"}, {'5',"795"},
{'U',"72"}, {'6',"796"},{'V',"73"}, {'7',"797"}, {'W',"74"}, {'8',"798"}, {'X',"75"},
{'9',"799"}, {'Y',"76"}, {'Z',"77"}};
key2Val = val2Key.ToDictionary(kv => kv.Value, kv => kv.Key);
}
public static string Encode(string s)
{
return string.Concat(s.ToUpper().ToCharArray()
.Where(c => val2Key.ContainsKey(c)).Select(c => val2Key[c]));
}
public static string Decode(string s)
{
return string.Concat(Regex.Matches(s, "79.|7.|3.|.").Cast<Match>()
.Where(m => key2Val.ContainsKey(m.Value)).Select(m => key2Val[m.Value]));
}
static void Main(string[] args)
{
var enc = Encode("One night-it was on the twentieth of March, 1888-I was returning");
Console.WriteLine(enc);
Console.WriteLine(Decode(enc));
Console.ReadLine();
}
}
}
139539363509369743061399059745399365901344308320791798798798367430685972839363935 ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
C++
#include <iostream>
#include <string>
#include <map>
#include <algorithm> // for min, max
using namespace std;
class StraddlingCheckerboard
{
map<char, string> table;
char first[10], second[10], third[10];
int rowU, rowV;
public:
StraddlingCheckerboard(const string &alphabet, int u, int v)
{
rowU = min(u, v);
rowV = max(u, v);
for(int i = 0, j = 0; i < 10; ++i)
{
if(i != u && i != v)
{
first[i] = alphabet[j];
table[alphabet[j]] = '0' + i;
++j;
}
second[i] = alphabet[i+8];
table[alphabet[i+8]] = '0' + rowU;
table[alphabet[i+8]] += '0' + i;
third[i] = alphabet[i+18];
table[alphabet[i+18]] = '0' + rowV;
table[alphabet[i+18]] += '0' + i;
}
}
string encode(const string &plain)
{
string out;
for(int i = 0; i < plain.size(); ++i)
{
char c = plain[i];
if(c >= 'a' && c <= 'z')
c += 'A' - 'a';
if(c >= 'A' && c <= 'Z')
out += table[c];
else if(c >= '0' && c <= '9')
{
out += table['/'];
out += c;
}
}
return out;
}
string decode(const string &cipher)
{
string out;
int state = 0;
for(int i = 0; i < cipher.size(); ++i)
{
int n = cipher[i] - '0';
char next = 0;
if(state == 1)
next = second[n];
else if(state == 2)
next = third[n];
else if(state == 3)
next = cipher[i];
else if(n == rowU)
state = 1;
else if(n == rowV)
state = 2;
else
next = first[n];
if(next == '/')
state = 3;
else if(next != 0)
{
state = 0;
out += next;
}
}
return out;
}
};
Test program:
int main()
{
StraddlingCheckerboard sc("HOLMESRTABCDFGIJKNPQUVWXYZ./", 3, 7);
string original = "One night-it was on the twentieth of March, 1888-I was returning";
string en = sc.encode(original);
string de = sc.decode(en);
cout << "Original: " << original << endl;
cout << "Encoded: " << en << endl;
cout << "Decoded: " << de << endl;
return 0;
}
Output:
Original: One night-it was on the twentieth of March, 1888-I was returning Encoded: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
D
Partially based on the PicoLisp version:
import std.stdio, std.algorithm, std.string, std.array;
immutable T = ["79|0|1|2|3|4|5|6|7|8|9", "|H|O|L||M|E|S||R|T",
"3|A|B|C|D|F|G|I|J|K|N", "7|P|Q|U|V|W|X|Y|Z|.|/"]
.map!(r => r.split("|")).array;
enum straddle = (in string s) pure /*nothrow @safe*/ =>
toUpper(s)
.split("")
.cartesianProduct(T)
.filter!(cL => cL[1].canFind(cL[0]))
.map!(cL => cL[1][0] ~ T[0][cL[1].countUntil(cL[0])])
.join;
string unStraddle(string s) pure nothrow @safe {
string result;
for (; !s.empty; s.popFront) {
immutable i = [T[2][0], T[3][0]].countUntil([s[0]]);
if (i >= 0) {
s.popFront;
immutable n = T[2 + i][T[0].countUntil([s[0]])];
if (n == "/") {
s.popFront;
result ~= s[0];
} else result ~= n;
} else
result ~= T[1][T[0].countUntil([s[0]])];
}
return result;
}
void main() {
immutable O = "One night-it was on the twentieth of March, 1888-I was returning";
writeln("Encoded: ", O.straddle);
writeln("Decoded: ", O.straddle.unStraddle);
}
- Output:
Encoded: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
Alternative Version
Same output:
import std.stdio, std.algorithm, std.ascii;
struct StraddlingCheckerboard {
private:
string[char] table;
char[10] first, second, third;
const int rowU, rowV;
public:
this(in string alphabet, in int u, in int v) pure nothrow {
rowU = min(u, v);
rowV = max(u, v);
int j = 0;
foreach (immutable i; 0 .. 10) {
if (i != u && i != v) {
first[i] = alphabet[j];
table[alphabet[j]] = digits[i .. i + 1];
j++;
}
second[i] = alphabet[i + 8];
table[alphabet[i + 8]] = [digits[rowU], digits[i]];
third[i] = alphabet[i + 18];
table[alphabet[i + 18]] = [digits[rowV], digits[i]];
}
}
string encode(in string plain) const pure nothrow {
string r;
foreach (immutable char c; plain) {
if (c.isLower) r ~= table[c.toUpper];
else if (c.isUpper) r ~= table[c];
else if (c.isDigit) r ~= table['/'] ~ c;
}
return r;
}
string decode(in string cipher) const pure nothrow {
string r;
int state = 0;
foreach (immutable char c; cipher) {
immutable int n = c - '0';
char next = '\0';
if (state == 1) next = second[n];
else if (state == 2) next = third[n];
else if (state == 3) next = c;
else if (n == rowU) state = 1;
else if (n == rowV) state = 2;
else next = first[n];
if (next == '/')
state = 3;
else if (next != 0) {
state = 0;
r ~= next;
}
}
return r;
}
}
void main() {
immutable orig =
"One night-it was on the twentieth of March, 1888-I was returning";
writeln("Original: ", orig);
const sc = StraddlingCheckerboard("HOLMESRTABCDFGIJKNPQUVWXYZ./",
3, 7);
const en = sc.encode(orig);
writeln("Encoded: ", en);
writeln("Decoded: ", sc.decode(en));
}
Dictionary-Based Version
import std.stdio, std.string, std.algorithm, std.regex, std.array, std.range, std.typecons;
immutable string[const string] val2key, key2val;
static this() pure /*nothrow @safe*/ {
immutable aa = ["A":"30", "B":"31", "C":"32", "D":"33", "E":"5", "F":"34", "G":"35",
"H":"0", "I":"36", "J":"37", "K":"38", "L":"2", "M":"4", ".":"78", "N":"39",
"/":"79", "O":"1", "0":"790", "P":"70", "1":"791", "Q":"71", "2":"792",
"R":"8", "3":"793", "S":"6", "4":"794", "T":"9", "5":"795", "U":"72",
"6":"796", "V":"73", "7":"797", "W":"74", "8":"798", "X":"75", "9":"799",
"Y":"76", "Z":"77"];
val2key = aa;
key2val = aa.byKeyValue.map!(t => tuple(t.value, t.key)).assocArray;
}
string encode(in string s) pure /*nothrow*/ @safe {
return s.toUpper.split("").map!(c => val2key.get(c, "")).join;
}
string decode(in string s) /*pure nothrow*/ @safe {
return s.matchAll("79.|3.|7.|.").map!(g => key2val.get(g[0], "")).join;
}
void main() @safe {
immutable s = "One night-it was on the twentieth of March, 1888-I was returning";
s.encode.writeln;
s.encode.decode.writeln;
}
- Output:
139539363509369743061399059745399365901344308320791798798798367430685972839363935 ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
FreeBASIC
Function Encipher(bd As String, pt As String) As String
Dim As String enc(256), row(3), r2d, r3d, d, num, ct
Dim As Integer i = 1, j, col
For j = 0 To 3
row(j) = Mid(bd, i, Instr(i, bd, Chr(10)) - i)
i = Instr(i, bd, Chr(10)) + 1
Next j
r2d = Mid(row(2), 1, 1)
r3d = Mid(row(3), 1, 1)
For col = 1 To 10
d = Mid(row(0), col+1, 1)
enc(Asc(Mid(row(1), col+1, 1))) = d
enc(Asc(Mid(row(2), col+1, 1))) = r2d + d
enc(Asc(Mid(row(3), col+1, 1))) = r3d + d
Next col
num = enc(Asc("/"))
enc(Asc("/")) = ""
enc(Asc(" ")) = ""
ct = ""
For i = 0 To Len(pt)-1
j = Asc(Mid(pt, i+1, 1))
If j <= Asc("9") And j >= Asc("0") Then
ct += num + Chr(j)
Else
If j <= Asc("z") And j >= Asc("a") Then
j -= Asc("a") - Asc("A")
End If
ct += enc(j)
End If
Next i
Return ct
End Function
Function Decipher(bd As String, ct As String) As String
Dim As String row(3), pt, b
Dim As Integer i = 1, j, cx(10), r2d, r3d, r, d
For j = 0 To 3
row(j) = Mid(bd, i, Instr(i, bd, Chr(10)) - i)
i = Instr(i, bd, Chr(10)) + 1
Next j
For i = 1 To 10
cx(Asc(Mid(row(0), i+1, 1)) - Asc("0")) = i
Next i
r2d = Asc(Mid(row(2), 1, 1)) - Asc("0")
r3d = Asc(Mid(row(3), 1, 1)) - Asc("0")
pt = ""
i = 0
While i < Len(ct)
d = Asc(Mid(ct, i+1, 1)) - Asc("0")
If d = r2d Then
r = 2
Elseif d = r3d Then
r = 3
Else
pt += Mid(row(1), cx(d)+1, 1)
i += 1
Continue While
End If
i += 1
b = Mid(row(r), cx(Asc(Mid(ct, i+1, 1)) - Asc("0"))+1, 1)
If b = "/" Then
i += 1
pt += Mid(ct, i+1, 1)
Else
pt += b
End If
i += 1
Wend
Return pt
End Function
Dim As String key = _
" 8752390146" + Chr(10) + _
" ET AON RIS" + Chr(10) + _
"5BC/FGHJKLM" + Chr(10) + _
"0PQD.VWXYZU"
Dim p As String = "you have put on 7.5 pounds since I saw you."
Print p
Dim c As String = Encipher(key, p)
Print c
Print Decipher(key, c)
Sleep
- Output:
Same as Go entry.
F#
(*
Encode and Decode using StraddlingCheckerboard
Nigel Galloway May 15th., 2017
*)
type G={n:char;i:char;g:System.Collections.Generic.Dictionary<(char*char),string>;e:System.Collections.Generic.Dictionary<char,string>}
member G.encode n=n|>Seq.map(fun n->if (n='/') then G.e.['/']+string n else match (G.e.TryGetValue(n)) with |(true,n)->n|(false,_)->G.e.['/']+string n)
member G.decode n =
let rec fn n = seq{ if not (Seq.isEmpty n)
then match (match Seq.head n with |g when g=G.n||g=G.i->(G.g.[(g,(Seq.item 1 n))],(Seq.skip 2 n))|g->(G.g.[('/',g)],(Seq.tail n))) with
|(a,b) when a="/"->yield string (Seq.head b); yield! fn (Seq.tail b)
|(a,b) ->yield a; yield! fn b
}
fn n
let G n i g e l z=
let a = new System.Collections.Generic.Dictionary<(char*char),string>()
let b = new System.Collections.Generic.Dictionary<char,string>()
Seq.iter2 (fun ng gn->a.[('/' ,char ng)]<-string gn;b.[gn]<-ng) (List.except [n;i] z) g
Seq.iter2 (fun ng gn->a.[(char n,char ng)]<-string gn;b.[gn]<-n+ng) z e
Seq.iter2 (fun ng gn->a.[(char i,char ng)]<-string gn;b.[gn]<-i+ng) z l
{n=char n;i=char i;g=a;e=b}
- Output:
let N = G "2" "6" "ETAONRIS" "BCDFGHJKLM" "PQ/UVWXYZ." ["0";"1";"2";"3";"4";"5";"6";"7";"8";"9"]
N.decode "450582425181653945125016505180125423293721256216286286288653970163758524"|>Seq.iter(fun n->printf "%s" n);; //ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
N.encode "IN THE WINTER 1965 WE WERE HUNGRY JUST BARELY ALIVE"|>Seq.iter(fun n->printfn "%s" n);; //8562 125062 658510762 62162962662562 65062 6507062 256352476762 26639162 20370286762 3288640
N.decode "8562 125062 658510762 62162962662562 65062 6507062 256352476762 26639162 20370286762 3288640"|>Seq.iter(fun n->printf "%s" n);; //IN THE WINTER 1965 WE WERE HUNGRY JUST BARELY ALIVE
Go
package main
import (
"fmt"
"strings"
)
func main() {
key := `
8752390146
ET AON RIS
5BC/FGHJKLM
0PQD.VWXYZU`
p := "you have put on 7.5 pounds since I saw you."
fmt.Println(p)
c := enc(key, p)
fmt.Println(c)
fmt.Println(dec(key, c))
}
func enc(bd, pt string) (ct string) {
enc := make(map[byte]string)
row := strings.Split(bd, "\n")[1:]
r2d := row[2][:1]
r3d := row[3][:1]
for col := 1; col <= 10; col++ {
d := string(row[0][col])
enc[row[1][col]] = d
enc[row[2][col]] = r2d+d
enc[row[3][col]] = r3d+d
}
num := enc['/']
delete(enc, '/')
delete(enc, ' ')
for i := 0; i < len(pt); i++ {
if c := pt[i]; c <= '9' && c >= '0' {
ct += num + string(c)
} else {
if c <= 'z' && c >= 'a' {
c -= 'a'-'A'
}
ct += enc[c]
}
}
return
}
func dec(bd, ct string) (pt string) {
row := strings.Split(bd, "\n")[1:]
var cx [10]int
for i := 1; i <= 10; i++ {
cx[row[0][i]-'0'] = i
}
r2d := row[2][0]-'0'
r3d := row[3][0]-'0'
for i := 0; i < len(ct); i++ {
var r int
switch d := ct[i]-'0'; d {
case r2d:
r = 2
case r3d:
r = 3
default:
pt += string(row[1][cx[d]])
continue
}
i++
if b := row[r][cx[ct[i]-'0']]; b == '/' {
i++
pt += string(ct[i])
} else {
pt += string(b)
}
}
return
}
- Output:
you have put on 7.5 pounds since I saw you. 01306592038080673955702555083069056649578462090130602 YOUHAVEPUTON7.5POUNDSSINCEISAWYOU.
Haskell
import Data.Char
import Data.Map
charToInt :: Char -> Int
charToInt c = ord c - ord '0'
-- Given a string, decode a single character from the string.
-- Return the decoded char and the remaining undecoded string.
decodeChar :: String -> (Char,String)
decodeChar ('7':'9':r:rs) = (r,rs)
decodeChar ('7':r:rs) = ("PQUVWXYZ. " !! charToInt r, rs)
decodeChar ('3':r:rs) = ("ABCDFGIJKN" !! charToInt r, rs)
decodeChar (r:rs) = ("HOL MES RT" !! charToInt r, rs)
-- Decode an entire string.
decode :: String -> String
decode [] = []
decode st = let (c, s) = decodeChar st in c:decode s
-- Given a string, decode a single character from the string.
-- Return the decoded char and the part of the encoded string
-- used to encode that character.
revEnc :: String -> (Char, String)
revEnc enc = let (dec, rm) = decodeChar enc in (dec, take (length enc - length rm) enc)
ds :: String
ds = ['0'..'9']
-- Decode all 1000 possible encodings of three digits and
-- use results to construct map used to encode.
encodeMap :: Map Char String
encodeMap = fromList [ revEnc [d2,d1,d0] | d2 <- ds, d1 <- ds, d0 <- ds ]
-- Encode a single char using encoding map.
encodeChar :: Char -> String
encodeChar c = findWithDefault "" c encodeMap
-- Encode an entire string.
encode :: String -> String
encode st = concatMap encodeChar $ fmap toUpper st
-- Test by encoding, decoding, printing results.
main = let orig = "One night-it was on the twentieth of March, 1888-I was returning"
enc = encode orig
dec = decode enc
in mapM_ putStrLn [ "Original: " ++ orig
, "Encoded: " ++ enc
, "Decoded: " ++ dec ]
- Output:
Original: One night-it was on the twentieth of March, 1888-I was returning Encoded: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
Icon and Unicon
Output:
text = "One night. it was on the twentieth of March, 1888. I was returning" encode = "1395393635097836974306139905974539936590134430832079179879879878367430685972839363935" decode = "ONENIGHT.ITWASONTHETWENTIETHOFMARCH1888.IWASRETURNING"
J
Solution:
'Esc Stop'=: '/.'
'Nums Alpha'=: '0123456789';'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
Charset=: Nums,Alpha,Stop
escapenum=: (,@:((; Esc&,)&>) Nums) rplc~ ] NB. escape numbers
unescapenum=: ((, ; ' '&,@])"1 0 Nums"_) rplc~ ] NB. unescape coded numbers (x is escape code, y is cipher)
expandKeyatUV=: 0:`[`(1 #~ 2 + #@])} #inv ]
makeChkBrd=: Nums , expandKeyatUV
chkbrd=: conjunction define
'uv key'=. n
board=. uv makeChkBrd key
select. m
case. 0 do. NB. encode
digits=. board 10&#.inv@i. escapenum y
' ' -.~ ,(":@{:"1 digits) ,.~ (1 1 0 2{":uv) {~ {."1 digits
case. 1 do. NB. decode
esc=. 0 chkbrd (uv;key) Esc NB. find code for Esc char
tmp=. esc unescapenum esc,'0',y
tmp=. ((":uv) ((-.@e.~ _1&|.) *. e.~) tmp) <;.1 tmp NB. box on chars from rows 0 2 3
idx=. (}. ,~ (1 1 0 2{":uv) ":@i. {.) each tmp NB. recreate indices for rows 0 2 3
idx=. ;(2&{. , [: ((0 1 $~ +:@#) #inv!.'1' ]) 2&}.) each idx NB. recreate indices for row 1
}.board {~ _2 (_&".)\ idx
end.
)
Example usage:
preprocess=: (#~ Charset e.~ ])@toupper NB. verb to compress out non-alphanumerics
chkbrdRC=: chkbrd (3 7;'HOLMESRTABCDFGIJKNPQUVWXYZ./') NB. define adverb by applying Rosetta Code key to chkbrd conjunction
0 chkbrdRC preprocess 'One night-it was on the twentieth of March, 1888-I was returning'
139539363509369743061399059745399365901344308320791798798798367430685972839363935
1 chkbrdRC 0 chkbrdRC preprocess 'One night-it was on the twentieth of March, 1888-I was returning'
ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
Or using the rules proposed by Util on the discussion page:
preprocess=: Stop&([`([: I. Charset -.@e.~ ])`]} toupper) NB. replace all non-alphanumerics with Stop
1 chkbrdRC 0 chkbrdRC preprocess 'One night-it was on the twentieth of March, 1888-I was returning'
ONE.NIGHT.IT.WAS.ON.THE.TWENTIETH.OF.MARCH..1888.I.WAS.RETURNING
Another method is to create a set of keys which correspond to the encoded letters in the alphabet. This allows for the relatively simple design of the encoding and decoding functions as they are essentially hash table lookups.
Solution:
NB. stops setcode alphabet
NB. creates verbs encode and decode which change between unencoded text and lists of encoded numbers
setcode=: 3 :0
2 6 setcode y
:
alphabet=: y, ,":"0 i.10
stops=. x
alphkeys=. (a: , ,&.> x) ([ -.~ [: , ,&.>/) i.10
esckey=. >(alphabet i. '/'){alphkeys
numkeys=. esckey&,&.> i.10
keys=. alphkeys,numkeys
encode=: ([: ; keys {~ alphabet&i.) :. decode
break=. </.~ i.@# - _1|. ([: >/\.&.|. e.&stops) + _1|.2*esckey&E.
decode=: (alphabet {~ keys i. break f.) :. encode
i.0 0
)
Example usage:
3 7 setcode 'HOLMESRTABCDFGIJKNPQUVWXYZ./'
preprocess=: (#~ alphabet e.~ ])@toupper
,":"0 encode message=: preprocess 'One night-it was on the twentieth of March, 1888-I was returning'
139539363509369743061399059745399365901344308320791798798798367430685972839363935
decode encode message
ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
]s=. ((10|+) 0 4 5 2$~$)&.encode message NB. scramble by taking a modular sum with 0 4 5 2 while encoded
OWVKRNEOAMTMXROWOHTMTMTROTQ4SEMRRLRZLVSTTLLOROMHALSFOHECMRWESWEE
((10|-) 0 4 5 2$~$)&.encode s
ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
Java
import java.util.HashMap;
import java.util.Map;
import java.util.regex.*;
public class StraddlingCheckerboard {
final static String[] keyvals = {"H:0", "O:1", "L:2", "M:4", "E:5", "S:6",
"R:8", "T:9", "A:30", "B:31", "C:32", "D:33", "F:34", "G:35", "I:36",
"J:37", "K:38", "N:39", "P:70", "Q:71", "U:72", "V:73", "W:74", "X:75",
"Y:76", "Z:77", ".:78", "/:79", "0:790", "1:791", "2:792", "3:793",
"4:794", "5:795", "6:796", "7:797", "8:798", "9:799"};
final static Map<String, String> val2key = new HashMap<>();
final static Map<String, String> key2val = new HashMap<>();
public static void main(String[] args) {
for (String keyval : keyvals) {
String[] kv = keyval.split(":");
val2key.put(kv[0], kv[1]);
key2val.put(kv[1], kv[0]);
}
String enc = encode("One night-it was on the twentieth of March, "
+ "1888-I was returning");
System.out.println(enc);
System.out.println(decode(enc));
}
static String encode(String s) {
StringBuilder sb = new StringBuilder();
for (String c : s.toUpperCase().split("")) {
c = val2key.get(c);
if (c != null)
sb.append(c);
}
return sb.toString();
}
static String decode(String s) {
Matcher m = Pattern.compile("(79.|3.|7.|.)").matcher(s);
StringBuilder sb = new StringBuilder();
while (m.find()) {
String v = key2val.get(m.group(1));
if (v != null)
sb.append(v);
}
return sb.toString();
}
}
139539363509369743061399059745399365901344308320791798798798367430685972839363935 ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
JavaScript
<script>
var alphabet=new Array("ESTONIA R","BCDFGHJKLM","PQUVWXYZ./") // scramble alphabet as you wish
var prefixes=new Array("",alphabet[0].indexOf(" "),alphabet[0].lastIndexOf(" "))
function straddle(message){
var out=""
message=message.toUpperCase()
message=message.replace(/([0-9])/g,"/$1") // dumb way to escape numbers
for(var i=0;i<message.length;i++){
var chr=message[i]
if(chr==" ")continue
for(var j=0;j<3;j++){
var k=alphabet[j].indexOf(chr)
if(k<0)continue
out+=prefixes[j].toString()+k
}
if(chr=="/")out+=message[++i]
}
return out
}
function unstraddle(message){
var out=""
var n,o
for(var i=0;i<message.length;i++){
n=message[i]*1
switch(n){
case prefixes[1]: o=alphabet[1][message[++i]];break
case prefixes[2]: o=alphabet[2][message[++i]];break
default: o=alphabet[0][n]
}
o=="/"?out+=message[++i]:out+=o
}
return out
}
str="One night-it was on the twentieth of March, 1888-I was returning."
document.writeln(str)
document.writeln(straddle(str))
document.writeln(unstraddle(straddle(str)))
</script>
Output:
One night-it was on the twentieth of March, 1888-I was returning. 34045747525284613427502840425027537379697175891898898898584619028294547488 ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING.
Julia
Unlike the precomputed table versions, this version takes a 30-character string specifying the 3 rows of the checkerboard as an argument, recomputing the lookup table each run, which allows easier changes of keys without modifying the code.
function straddlingcheckerboard(board, msg, doencode)
lookup = Dict()
reverselookup = Dict()
row2 = row3 = slash = -1
function encode(x)
s = ""
for ch in replace(replace(uppercase(x), r"([01-9])", s";=;\1"), r";=;", slash)
c = string(ch)
if haskey(lookup, c)
s *= lookup[c]
elseif contains("0123456789", c)
s *= c
end
end
s
end
function decode(x)
s = ""
i = 1
while i <= length(x)
c = string(x[i])
if haskey(reverselookup, c)
s *= reverselookup[c]
i += 1
else
if "$c$(x[i+1])" == slash
s *= string(x[i+2])
i += 3
else
s *= reverselookup["$c$(x[i+1])"]
i += 2
end
end
end
s
end
for (i,c) in enumerate(board)
c = string(c)
if c == " "
if row2 == -1
row2 = i-1
else
row3 = i-1
end
else
if i < 11
lookup[c] = "$(i-1)"; reverselookup["$(i-1)"] = c
elseif i < 21
lookup[c] = "$row2$(i-11)"; reverselookup["$row2$(i-11)"] = c
else
lookup[c] = "$row3$(i-21)"; reverselookup["$row3$(i-21)"] = c
end
if c == "/"
slash = lookup[c]
end
end
end
doencode ? encode(msg) : decode(msg)
end
btable = "ET AON RISBCDFGHJKLMPQ/UVWXYZ."
message = "Thecheckerboardcakerecipespecifies3largeeggsand2.25cupsofflour."
encoded = straddlingcheckerboard(btable, message, true)
decoded = straddlingcheckerboard(btable, encoded, false)
println("Original: $message\nEncoded: $encoded\nDecoded: $decoded")
- Output:
Original: Thecheckerboardcakerecipespecifies3largeeggsand2.25cupsofflour. Encoded: 125021250212707204372221327070218600960021823809623283724002424935226226962262521636094232328463769 Decoded: THECHECKERBOARDCAKERECIPESPECIFIES3LARGEEGGSAND2.25CUPSOFFLOUR.
Kotlin
// version 1.2.0
val board = "ET AON RISBCDFGHJKLMPQ/UVWXYZ."
val digits = "0123456789"
val rows = " 26"
val escape = "62"
val key = "0452"
fun encrypt(message: String): String {
val msg = message.toUpperCase()
.filter { (it in board || it in digits) && it !in " /" }
val sb = StringBuilder()
for (c in msg) {
val idx = board.indexOf(c)
if (idx > -1) {
val row = idx / 10
val col = idx % 10
sb.append(if (row == 0) "$col" else "${rows[row]}$col")
}
else {
sb.append("$escape$c")
}
}
val enc = sb.toString().toCharArray()
for ((i, c) in enc.withIndex()) {
val k = key[i % 4] - '0'
if (k == 0) continue
val j = c - '0'
enc[i] = '0' + ((j + k) % 10)
}
return String(enc)
}
fun decrypt(encoded: String): String {
val enc = encoded.toCharArray()
for ((i, c) in enc.withIndex()) {
val k = key[i % 4] - '0'
if (k == 0) continue
val j = c - '0'
enc[i] = '0' + if (j >= k) (j - k) % 10 else (10 + j - k) % 10
}
val len = enc.size
val sb = StringBuilder()
var i = 0
while (i < len) {
val c = enc[i]
val idx = rows.indexOf(c)
if (idx == -1) {
val idx2 = c - '0'
sb.append(board[idx2])
i++
}
else if ("$c${enc[i + 1]}" == escape) {
sb.append(enc[i + 2])
i += 3
}
else {
val idx2 = idx * 10 + (enc[i + 1] - '0')
sb.append(board[idx2])
i += 2
}
}
return sb.toString()
}
fun main(args: Array<String>) {
val messages = listOf(
"Attack at dawn",
"One night-it was on the twentieth of March, 1888-I was returning",
"In the winter 1965/we were hungry/just barely alive",
"you have put on 7.5 pounds since I saw you.",
"The checkerboard cake recipe specifies 3 large eggs and 2.25 cups of flour."
)
for (message in messages) {
val encrypted = encrypt(message)
val decrypted = decrypt(encrypted)
println("\nMessage : $message")
println("Encrypted : $encrypted")
println("Decrypted : $decrypted")
}
}
- Output:
Message : Attack at dawn Encrypted : 3565257935743007 Decrypted : ATTACKATDAWN Message : One night-it was on the twentieth of March, 1888-I was returning Encrypted : 495786945533698149645468540384645875238925776668221480708005915367278976 Decrypted : ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING Message : In the winter 1965/we were hungry/just barely alive Encrypted : 89645417896270736648201450026959060839767024608116557470618482160 Decrypted : INTHEWINTER1965WEWEREHUNGRYJUSTBARELYALIVE Message : you have put on 7.5 pounds since I saw you. Encrypted : 61983605685800834914704829124087264189730245691940889 Decrypted : YOUHAVEPUTON7.5POUNDSSINCEISAWYOU. Message : The checkerboard cake recipe specifies 3 large eggs and 2.25 cups of flour. Encrypted : 160225770664742408892673362274738052905225343251668487244454469139746678907466041088039436848815704 Decrypted : THECHECKERBOARDCAKERECIPESPECIFIES3LARGEEGGSAND2.25CUPSOFFLOUR.
Lua
local brd = { "HOL MES RT", "ABCDFGIJKN", "PQUVWXYZ./" }
local dicE, dicD, s1, s2 = {}, {}, 0, 0
function dec( txt )
local i, numb, s, t, c = 1, false
while( i < #txt ) do
c = txt:sub( i, i )
if not numb then
if tonumber( c ) == s1 then
i = i + 1; s = string.format( "%d%s", s1, txt:sub( i, i ) )
t = dicD[s]
elseif tonumber( c ) == s2 then
i = i + 1; s = string.format( "%d%s", s2, txt:sub( i, i ) )
t = dicD[s]
else
t = dicD[c]
end
if t == "/" then
numb = true
else
io.write( t )
end
else
io.write( c )
numb = false
end
i = i + 1
end
print()
end
function enc( txt )
local c
for i = 1, #txt do
c = txt:sub( i, i )
if c >= "A" and c <= "Z" then
io.write( dicE[c] )
elseif c >= "0" and c <= "9" then
io.write( string.format( "%s%s", dicE["/"], c ) )
end
end
print()
end
function createDictionaries()
for i = 1, 10 do
c = brd[1]:sub( i, i )
if c == " " then
if s1 == 0 then s1 = i - 1
elseif s2 == 0 then s2 = i - 1 end
else
dicE[c] = string.format( "%d", i - 1 )
dicD[string.format( "%d", i - 1 )] = c
end
end
for i = 1, 10 do
dicE[brd[2]:sub( i, i )] = string.format( "%d%d", s1, i - 1 )
dicE[brd[3]:sub( i, i )] = string.format( "%d%d", s2, i - 1 )
dicD[string.format( "%d%d", s1, i - 1 )] = brd[2]:sub( i, i )
dicD[string.format( "%d%d", s2, i - 1 )] = brd[3]:sub( i, i )
end
end
function enterText()
createDictionaries()
io.write( "\nEncrypt or Decrypt (E/D)? " )
d = io.read()
io.write( "\nEnter the text:\n" )
txt = io.read():upper()
if d == "E" or d == "e" then enc( txt )
elseif d == "D" or d == "d" then dec( txt )
end
end
-- entry point
enterText()
- Output:
Lua 5.3.3 Copyright (C) 1994-2016 Lua.org, PUC-Rio > dofile "straddling.lua" Encrypt or Decrypt (E/D)? e Enter the text: One night-it was on the twentieth of March, 1888-I was returning 139539363509369743061399059745399365901344308320791798798798367430685972839363935 > dofile "straddling.lua" Encrypt or Decrypt (E/D)? d Enter the text: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
M2000 Interpreter
module Straddling_checkerboard {
function encrypt$(message$, alphabet) {
message$=filter$(ucase$(message$),"-/,. ")
def num1, num2
num1=instr(alphabet#val$(0)," ")
num2=instr(alphabet#val$(0)," ", num1+1)-1
num1--
escapenum=instr(alphabet#val$(2),"/")-1
escapenum1=instr(alphabet#val$(2),".")-1
num0=-10
num10=num1*10-20
num20=num2*10-30
numbers=(escapenum+num2*10)*10
numbers1=(escapenum1+num2*10)*10
boardrow=each(alphabet)
cipherkey$="0123456789" : while boardrow :cipherkey$+=array$(boardrow) :end while
encoded$=""
for i=1 to len(message$)
n=instr(cipherkey$, mid$(message$,i,1))-1
if n<10 then
n+=if(random(10)<5->numbers, numbers1)
else.if n<20 then
n+=num0
else.if n<30 then
n+=num10
else
n+=num20
end if
encoded$+=str$(n,"")
next
=encoded$
}
function decrypt$(encoded$, alphabet) {
def num1, num2
num1=instr(alphabet#val$(0)," ")
num2=instr(alphabet#val$(0)," ", num1+1)-1
num1--
escapenum=instr(alphabet#val$(2),"/")-1
escapenum1=instr(alphabet#val$(2),".")-1
def i=1, decoded$
j=len(encoded$)+1
while i<j
m=val(mid$(encoded$,i,1))
if m=num1 then
decoded$+=mid$(alphabet#val$(1), val(mid$(encoded$,i+1,1))+1,1)
i++
else.if m=num2 then
if i+1<j then
mm=val(mid$(encoded$,i+1,1))
if mm=escapenum or mm=escapenum1 then
decoded$+=mid$(encoded$,i+2,1)
i+=2
else
decoded$+=mid$(alphabet#val$(2), val(mid$(encoded$,i+1,1))+1,1)
i++
end if
else
decoded$+=mid$(alphabet#val$(2), val(mid$(encoded$,i+1,1))+1,1)
i++
end if
else
decoded$+=mid$(alphabet#val$(0), m+1,1)
end if
i++
end while
=decoded$
}
Module DisplayBoard (alphabet, &Doc$){
num1=instr(alphabet#val$(0)," ")
num2=instr(alphabet#val$(0)," ", num1+1)-1
num1--
escapenum=instr(alphabet#val$(2),"/")-1
escapenum1=instr(alphabet#val$(2),".")-1
\\ display straddling checkerboard
checkerboard =cons(("0123456789",),alphabet)
labels=(" "," ",str$(num1,""), str$(num2,""))
disp=each(checkerboard)
while disp
Doc$=labels#val$(disp^)+" "+array$(disp)+{
}
end while
}
Document Doc$
Const nl$={
}
Function OnePad$(Message$, PadSerial, n=1) {
x=random(!PadSerial) ' push old seed, set the new one
encoded$=""
for i=1 to len(Message$)
encoded$+=str$((val(mid$(Message$,i,1))+10+n*random(1, 10))mod 10,"")
next i
x=random(!) ' restore old seed
=encoded$
}
\\ select a random alphabet
select case random(1,3)
case 1
alphabet=("ESTONIAR ","BCDFGHJKLM","/PQUVWXYZ.") : Doc$="First "+nl$
case 2
alphabet=("ET AON RIS","BCDFGHJKLM","PQ/UVWXYZ.") : Doc$="Second"+nl$
case 3
alphabet=("ESTONIAR ","BCDFGHJKLM","PQU.VWXYZ/") : Doc$="Third"+nl$
end select
DisplayBoard alphabet, &Doc$
msg$="One night-it was on the twentieth of March, 1888-I was returning"
Doc$= "original message:"+nl$
Doc$= msg$+nl$
Doc$= "encrypted message:"+nl$
crypt$=encrypt$(msg$, alphabet)
Doc$=crypt$+nl$
serial=random(1234567,9345678)
Doc$= "encrypted message using one pad using serial:"+str$(serial)+nl$
crypt$=OnePad$(crypt$, serial)
Doc$=crypt$+nl$
Doc$= "decrypted message using one pad:"+nl$
crypt$=OnePad$(crypt$, serial,-1)
Doc$=crypt$+nl$
Doc$= "decrypted message:"+nl$
Doc$=decrypt$(crypt$, alphabet)
Print #-2, Doc$ ' render to console using new lines codes from Doc$
Clipboard Doc$
}
Straddling_checkerboard- Output:
First 0123456789 ESTONIAR 8 BCDFGHJKLM 9 /PQUVWXYZ. original message: One night-it was on the twentieth of March, 1888-I was returning encrypted message: 340458485252956134285029504250285383896781859019989989985956170293745484 encrypted message using one pad using serial: 7745037 811354381526409435575275634030693156335135381796263056259799033307312819 decrypted message using one pad: 340458485252956134285029504250285383896781859019989989985956170293745484 decrypted message: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING Second 0123456789 ET AON RIS 2 BCDFGHJKLM 6 PQ/UVWXYZ. original message: One night-it was on the twentieth of March, 1888-I was returning encrypted message: 450582425181653945125016505180125423293721256216986986288653970163758524 encrypted message using one pad using serial: 8485713 339360039726873741044731817004082441136155821888897367354417518371636266 decrypted message using one pad: 450582425181653945125016505180125423293721256216986986288653970163758524 decrypted message: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
Nim
I used the same example as in the Go solution (and, fortunately, got the same result).
import strutils, tables
const
FullStop = '.'
Escape = '/'
type Checkerboard = object
encryptTable: Table[char, string]
decryptTable: Table[string, char]
proc initCheckerboard(digits: string; row1, row2, row3: string): Checkerboard =
## Initialize a checkerboard with given digits in row 0 and the following given rows.
## No sanity check is performed.
var rowChars: seq[char] # The two characters to use to identify rows 2 and 3.
# Process row 1.
for col, ch in row1:
if ch == ' ':
rowChars.add digits[col]
else:
result.encryptTable[ch] = $digits[col]
if rowChars.len != 2:
raise newException(ValueError, "expected two blank spots in first letter row.")
# Add rows 2 and 3.
for col, ch in row2:
result.encryptTable[ch] = rowChars[0] & digits[col]
for col, ch in row3:
result.encryptTable[ch] = rowChars[1] & digits[col]
if Escape notin result.encryptTable:
raise newException(ValueError, "missing Escape character.")
# Build decrypt table from encrypt table.
for c, s in result.encryptTable.pairs:
result.decryptTable[s] = c
proc encrypt(board: Checkerboard; message: string): string =
## Encrypt a string.
let message = message.toUpperAscii
for ch in message:
case ch
of 'A'..'Z', FullStop, Escape:
result.add board.encryptTable[ch]
of '0'..'9':
result.add board.encryptTable[Escape]
result.add ch
else:
discard # Ignore other characters.
proc raiseError() =
## Raise a ValueError to signal a corrupt message.
raise newException(ValueError, "corrupt message")
proc decrypt(board: Checkerboard; message: string): string =
## Decrypt a message.
var escaped = false # Escape char previously encountered.
var str = "" # Current sequence of characters (contains 0, 1 or 2 chars).
for ch in message:
if ch notin '0'..'9': raiseError()
if escaped:
# Digit is kept as is.
result.add ch
escaped = false
else:
# Try to decrypt this new digit.
str.add ch
if str in board.decryptTable:
let c = board.decryptTable[str]
if c == Escape: escaped = true
else: result.add c
str.setLen(0)
elif str.len == 2:
# Illegal combination of two digits.
raiseError()
when isMainModule:
let board = initCheckerboard("8752390146", "ET AON RIS", "BC/FGHJKLM", "PQD.VWXYZU")
let message = "you have put on 7.5 pounds since I saw you."
echo "Message: ", message
let crypted = board.encrypt(message)
echo "Crypted: ", crypted
echo "Decrypted: ", board.decrypt(crypted)
- Output:
Message: you have put on 7.5 pounds since I saw you. Crypted: 01306592038080673955702555083069056649578462090130602 Decrypted: YOUHAVEPUTON7.5POUNDSSINCEISAWYOU.
Perl
use strict;
use warnings;
use feature 'say';
use List::Util <min max>;
my(%encode,%decode,@table);
sub build {
my($u,$v,$alphabet) = @_;
my(@flat_board,%p2c,%c2p);
my $numeric_escape = '/';
@flat_board = split '', uc $alphabet;
splice @flat_board, min($u,$v), 0, undef;
splice @flat_board, max($u,$v), 0, undef;
push @table, [' ', 0..9];
push @table, [' ', map { defined $_ ? $_ : ' '} @flat_board[ 0 .. 9] ];
push @table, [$u, @flat_board[10 .. 19]];
push @table, [$v, @flat_board[20 .. 29]];
my @nums = my @order = 0..9;
push @nums, (map { +"$u$_" } @order), map { +"$v$_" } @order;
@c2p{@nums} = @flat_board;
for (keys %c2p) { delete $c2p{$_} unless defined $c2p{$_} }
@p2c{values %c2p} = keys %c2p;
$p2c{$_} = $p2c{$numeric_escape} . $_ for 0..9;
while (my ($k, $v) = each %p2c) {
$encode{$k} = $v;
$decode{$v} = $k unless $k eq $numeric_escape;
}
}
sub decode {
my($string) = @_;
my $keys = join '|', keys %decode;
$string =~ s/($keys)/$decode{$1}/gr;
}
sub encode {
my($string) = uc shift;
$string =~ s#(.)#$encode{$1} // $encode{'.'}#ger;
}
my $sc = build(3, 7, 'HOLMESRTABCDFGIJKNPQUVWXYZ./');
say join ' ', @$_ for @table;
say '';
say 'Original: ', my $original = 'One night-it was on the twentieth of March, 1888-I was returning';
say 'Encoded: ', my $en = encode($original);
say 'Decoded: ', decode($en);
- Output:
0 1 2 3 4 5 6 7 8 9 H O L M E S R T 3 A B C D F G I J K N 7 P Q U V W X Y Z . / Original: One night-it was on the twentieth of March, 1888-I was returning Encoded: 13957839363509783697874306781397890578974539936590781347843083207878791798798798783678743067885972839363935 Decoded: ONE.NIGHT.IT.WAS.ON.THE.TWENTIETH.OF.MARCH..1888.I.WAS.RETURNING
Phix
with javascript_semantics function read_table(string cb) sequence encode = repeat("",128), decode = repeat(0,128), row = {0} if length(cb)!=30 then crash("table wrong length") end if for i=1 to 30 do integer c = cb[i] if c=' ' then row &= i-1 else integer code = row[floor((i-1)/10)+1]*10+mod((i-1),10) encode[c] = sprintf("%d",code) decode[code+1] = c end if end for return {encode, decode} end function function encipher(sequence encode, string s, bool strip=false) string res = "" for i=1 to length(s) do integer c = upper(s[i]), code if c>='0' and c<='9' then res &= encode['.']&c elsif c>='A' and c<='Z' then res &= encode[c] elsif not strip or c='/' then -- (see note) res &= encode['/'] end if end for return res end function function decipher(sequence decode, string s, bool strip=false) string res = "" integer i = 1 while i<=length(s) do integer c = s[i]-'0'+1 if decode[c]=0 then i += 1 c = (c-1)*10+s[i]-'0'+1 end if integer d = decode[c] if d='.' then i += 1 d = s[i] elsif d='/' and not strip then -- (see note) d = ' ' end if res &= d i += 1 end while return res end function constant cb = "ET AON RIS"& "BCDFGHJKLM"& "PQ/UVWXYZ." sequence {encode,decode} = read_table(cb) -- Note there is a subtle difference in space handling, to exactly match other outputs try -- {encode,decode} = read_table("HOL MES RTABCDFGIJKNPQUVWXYZ/.") instead of -- {encode,decode} = read_table("HOL MES RTABCDFGIJKNPQUVWXYZ./"), and -- {encode,decode} = read_table("ET AON RISBCDFGHJKLMPQ.UVWXYZ/") instead of -- {encode,decode} = read_table("ET AON RISBCDFGHJKLMPQ/UVWXYZ.") string msg = "In the winter 1965/we were hungry/just barely alive" printf(1,"message: %s\n", {msg}) string enc = encipher(encode, msg), dec = decipher(decode, enc) printf(1,"encoded: %s\n", {enc}) printf(1,"decoded: %s\n", {dec}) printf(1,"\nNo spaces:\n") enc = encipher(encode, msg, true) dec = decipher(decode, enc, true) printf(1,"encoded: %s\n", {enc}) printf(1,"decoded: %s\n", {dec})
- Output:
message: In the winter 1965/we were hungry/just barely alive encoded: 85621250626585107626916996966956265062650706225635247676226639162203702867623288640 decoded: IN THE WINTER 1965 WE WERE HUNGRY JUST BARELY ALIVE No spaces: encoded: 851250658510769169969669562650650702563524767622663912037028673288640 decoded: INTHEWINTER1965/WEWEREHUNGRY/JUSTBARELYALIVE
PHP
$key2val = ["A"=>"30", "B"=>"31", "C"=>"32", "D"=>"33", "E"=>"5", "F"=>"34", "G"=>"35",
"H"=>"0", "I"=>"36", "J"=>"37", "K"=>"38", "L"=>"2", "M"=>"4", "."=>"78", "N"=>"39",
"/"=>"79", "O"=>"1", "0"=>"790", "P"=>"70", "1"=>"791", "Q"=>"71", "2"=>"792",
"R"=>"8", "3"=>"793", "S"=>"6", "4"=>"794", "T"=>"9", "5"=>"795", "U"=>"72",
"6"=>"796", "V"=>"73", "7"=>"797", "W"=>"74", "8"=>"798", "X"=>"75", "9"=>"799",
"Y"=>"76", "Z"=>"77"];
$val2key = array_flip($key2val);
function encode(string $s) : string {
global $key2val;
$callback = function($c) use ($key2val) { return $key2val[$c] ?? ''; };
return implode(array_map($callback, str_split(strtoupper($s))));
}
function decode(string $s) : string {
global $val2key;
$callback = function($c) use ($val2key) { return $val2key[$c] ?? ''; };
preg_match_all('/79.|7.|3.|./', $s, $m);
return implode(array_map($callback, $m[0]));
}
function main($s) {
$encoded = encode($s);
echo $encoded;
echo "\n";
echo decode($encoded);
}
main('One night-it was on the twentieth of March, 1888-I was returning');
139539363509369743061399059745399365901344308320791798798798367430685972839363935 ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
PicoLisp
(de *Straddling
(NIL "H" "O" "L" NIL "M" "E" "S" NIL "R" "T")
("3" "A" "B" "C" "D" "F" "G" "I" "J" "K" "N")
("7" "P" "Q" "U" "V" "W" "X" "Y" "Z" "." "/")
("79" "0" "1" "2" "3" "4" "5" "6" "7" "8" "9") )
(de straddle (Str)
(pack
(mapcar
'((C)
(pick
'((L)
(and
(index C (cdr L))
(cons (car L) (dec @)) ) )
*Straddling ) )
(chop (uppc Str)) ) ) )
(de unStraddle (Str)
(pack
(make
(for (L (chop Str) L)
(let C (pop 'L)
(setq C
(if (assoc C *Straddling)
(get (cdr @) (inc (format (pop 'L))))
(get (cdar *Straddling) (inc (format C))) ) )
(link (if (= "/" C) (pop 'L) C)) ) ) ) ) )Output:
: (straddle "One night-it was on the twentieth of March, 1888-I was returning") -> "139539363509369743061399059745399365901344308320791798798798367430685972839363935" : (unStraddle @) -> "ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING"
PureBasic
Procedure.s encrypt_SC(originalText.s, alphabet.s, blank_1, blank_2)
Static notEscape.s = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ."
Protected preDigit_1.s = Str(blank_1), preDigit_2.s = Str(blank_2)
Protected i, index, curChar.s, escapeChar.s, outputText.s
Protected NewMap cipher.s()
;build cipher reference
alphabet = UCase(alphabet)
For i = 1 To 28
curChar = Mid(alphabet, i, 1)
If Not FindString(notEscape, curChar)
escapeChar = curChar
EndIf
Select i
Case 1 To 8
If index = blank_1 Or index = blank_2: index + 1: EndIf ;adjust index for blank
cipher(curChar) = Str(index)
index + 1
Case 9 To 18
cipher(curChar) = preDigit_1 + Str(i - 9)
Case 19 To 28
cipher(curChar) = preDigit_2 + Str(i - 19)
EndSelect
Next
For i = 0 To 9: cipher(Str(i)) = cipher(escapeChar) + Str(i): Next
;encrypt each character
originalText = UCase(originalText)
Protected length = Len(originalText)
For i = 1 To length
outputText + cipher(Mid(originalText, i, 1))
Next
ProcedureReturn outputText
EndProcedure
Procedure.s decrypt_SC(cipherText.s, alphabet.s, blank_1, blank_2)
Static notEscape.s = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ."
Protected preDigit_1.s = Str(blank_1), preDigit_2.s = Str(blank_2)
Protected i, index, curChar.s, escapeCipher.s, outputText.s
Protected NewMap cipher.s()
;build decipher reference
alphabet = UCase(alphabet)
For i = 1 To 28
curChar = Mid(alphabet, i, 1)
Select i
Case 1 To 8
If index = blank_1 Or index = blank_2: index + 1: EndIf ;adjust index for blank
cipher(Str(index)) = curChar
index + 1
Case 9 To 18
cipher(preDigit_1 + Str(i - 9)) = curChar
Case 19 To 28
cipher(preDigit_2 + Str(i - 19)) = curChar
EndSelect
If Not FindString(notEscape, curChar)
escapeCipher = MapKey(cipher())
EndIf
Next
For i = 0 To 9: cipher(escapeCipher + Str(i)) = Str(i): Next
;decrypt each character
Protected length = Len(cipherText)
index = 1
While index <=length
curChar = Mid(cipherText, index, 1)
If curChar = preDigit_1 Or curChar = preDigit_2
curChar = Mid(cipherText, index, 2)
If curChar = escapeCipher: curChar = Mid(cipherText, index, 3): EndIf
EndIf
outputText + cipher(curChar)
index + Len(curChar)
Wend
ProcedureReturn outputText
EndProcedure
If OpenConsole()
Define message.s = "One night-it was on the twentieth of March, 1888-I was returning"
Define cipher.s = "HOLMESRTABCDFGIJKNPQUVWXYZ./", encoded.s
PrintN("Original: " + message)
encoded = encrypt_SC(message, cipher, 3, 7)
PrintN("encoded: " + encoded)
PrintN("decoded: " + decrypt_SC(encoded, cipher, 3, 7))
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
CloseConsole()
EndIf
Sample output:
Original: One night-it was on the twentieth of March, 1888-I was returning encoded: 13953936350936974306139905974539936590134430832079179879879836743068597 2839363935 decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
Python
Partially based on the PicoLisp version:
T = [["79", "0", "1", "2", "3", "4", "5", "6", "7", "8", "9"],
["", "H", "O", "L", "", "M", "E", "S", "", "R", "T"],
["3", "A", "B", "C", "D", "F", "G", "I", "J", "K", "N"],
["7", "P", "Q", "U", "V", "W", "X", "Y", "Z", ".", "/"]]
def straddle(s):
return "".join(L[0]+T[0][L.index(c)] for c in s.upper() for L in T if c in L)
def unstraddle(s):
s = iter(s)
for c in s:
if c in [T[2][0], T[3][0]]:
i = [T[2][0], T[3][0]].index(c)
n = T[2 + i][T[0].index(s.next())]
yield s.next() if n == "/" else n
else:
yield T[1][T[0].index(c)]
O = "One night-it was on the twentieth of March, 1888-I was returning"
print "Encoded:", straddle(O)
print "Decoded:", "".join(unstraddle(straddle(O)))
Output:
Encoded: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
Racket
Based in the PicoLisp version.
We store the straddling checkerboard in a structure, so it can be reused or changed for the different examples. The “constructor” transforms the lines of the checkboard into an internal representation.
#lang racket
(struct *straddling (header main original)
#:reflection-name 'straddling
#:methods gen:custom-write
[(define (write-proc board port mode)
(write-string "#<straddling " port)
(write (*straddling-original board) port)
(write-string ">" port))])
(define string->vector (compose list->vector string->list))
(define (straddling . lines)
(define header-tail (reverse
(for/fold ([rev-ret '()])
([char (in-list (string->list (car lines)))]
[i (in-naturals)])
(if (equal? char #\space)
(cons (number->string i) rev-ret)
rev-ret))))
(define main (list->vector
(map string->vector
(cons "0123456789"
(map string-upcase
lines)))))
(define temporal-board
(*straddling (list->vector (list* "?" "" header-tail)) main lines))
(define escape (straddling-encode-char #\/ temporal-board))
(*straddling (list->vector (list* escape "" header-tail)) main lines))
Now we define the functions to straddle and unstraddle the message.
(define (straddling-encode-char char board)
(or (for/or ([head (in-vector (*straddling-header board))]
[line (in-vector (*straddling-main board))])
(let ([pos (vector-member char line)])
(if pos
(string-append head (number->string pos))
#f)))
""))
(define (straddle message board)
(apply string-append
(map (lambda (char)
(if (or (equal? char #\space) (equal? char #\/))
""
(straddling-encode-char char board)))
(string->list (string-upcase message)))))
(define (unstraddle message board)
(define char->string string)
(define (straddling-decode-char str row)
(vector-ref (vector-ref (*straddling-main board) row) (string->number str)))
(list->string
(reverse
(let-values ([(row rev-ret)
(for/fold ([row #f] ;row to read in multichar codes
;#f means start of new code
[rev-ret '()]) ;result
([str (map char->string (string->list (string-upcase message)))])
(if (not row)
(let ([pos (vector-member str (*straddling-header board))])
(if pos
(values pos rev-ret)
(values #f (cons (straddling-decode-char str 1) rev-ret))))
(let ([decoded (straddling-decode-char str row)])
(if (equal? decoded #\/)
(values 0 rev-ret)
(values #f (cons decoded rev-ret))))))])
(unless row ;check that last number was not missing
rev-ret)))))
Two examples:
(define (test-straddling message board)
(let* ([encoded (straddle message board)]
[decoded (unstraddle encoded board)])
(displayln board)
(displayln message)
(displayln encoded)
(displayln decoded)))
(test-straddling "One night-it was on the twentieth of March, 1888-I was returning"
(straddling "HOL MES RT"
"ABCDFGIJKN"
"PQUVWXYZ./"))
(newline)
(test-straddling "One night-it was on the twentieth of March, 1888-I was returning"
(straddling "ET AON RIS"
"BCDFGHJKLM"
"PQ/UVWXYZ."))
- Output:
#<straddling ("HOL MES RT" "ABCDFGIJKN" "PQUVWXYZ./")>
One night-it was on the twentieth of March, 1888-I was returning
139539363509369743061399059745399365901344308320791798798798367430685972839363935
ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
#<straddling ("ET AON RIS" "BCDFGHJKLM" "PQ/UVWXYZ.")>
One night-it was on the twentieth of March, 1888-I was returning
450582425181653945125016505180125423293721256216286286288653970163758524
ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
Raku
(formerly Perl 6)
The .trans method in Raku improves on Perl 5's tr/// by allowing multi-character translation tables.
We build the full table during .new, which simplifies .encode and .decode.
class Straddling_Checkerboard {
has @!flat_board; # 10x3 stored as 30x1
has $!plain2code; # full translation table, invertable
has @!table; # Printable layout, like Wikipedia entry
my $numeric_escape = '/';
my $exclude = /<-[A..Z0..9.]>/; # Omit the escape character
method display_table { gather { take ~ .list for @!table } };
method decode ( Str $s --> Str ) {
$s.trans($!plain2code.antipairs);
}
method encode ( Str $s, :$collapse? --> Str ) {
my $replace = $collapse ?? '' !! '.';
$s.uc.subst( $exclude, $replace, :g ).trans($!plain2code);
}
submethod BUILD ( :$alphabet, :$u where 0..9, :$v where 0..9 ) {
die if $u == $v;
die if $alphabet.comb.sort.join ne [~] flat './', 'A'..'Z';
@!flat_board = $alphabet.uc.comb;
@!flat_board.splice( $u min $v, 0, Any );
@!flat_board.splice( $u max $v, 0, Any );
@!table = [ ' ',| [ 0 .. 9] ],
[ ' ',|@!flat_board[ 0 .. 9].map: {.defined ?? $_ !! ' '} ],
[ $u, |@!flat_board[10 .. 19] ],
[ $v, |@!flat_board[20 .. 29] ];
my @order = 0..9; # This may be passed as a param in the future
my @nums = flat @order,
@order.map({ +"$u$_" }),
@order.map({ +"$v$_" });
my %c2p = @nums Z=> @!flat_board;
%c2p{$_}:delete if %c2p{$_} eqv Any for keys %c2p;
my %p2c = %c2p.invert;
%p2c{$_} = %p2c{$numeric_escape} ~ $_ for 0..9;
$!plain2code = [%p2c.keys] => [%p2c.values];
}
}
sub MAIN ( :$u = 3, :$v = 7, :$alphabet = 'HOLMESRTABCDFGIJKNPQUVWXYZ./' ) {
my Straddling_Checkerboard $sc .= new: :$u, :$v, :$alphabet;
$sc.display_table;
for 0..1 -> $collapse {
my $original = 'One night-it was on the twentieth of March, 1888-I was returning';
my $en = $sc.encode($original, :$collapse);
my $de = $sc.decode($en);
say '';
say "Original: $original";
say "Encoded: $en";
say "Decoded: $de";
}
}
Output:
0 1 2 3 4 5 6 7 8 9 H O L M E S R T 3 A B C D F G I J K N 7 P Q U V W X Y Z . / Original: One night-it was on the twentieth of March, 1888-I was returning Encoded: 13957839363509783697874306781397890578974539936590781347843083207878791798798798783678743067885972839363935 Decoded: ONE.NIGHT.IT.WAS.ON.THE.TWENTIETH.OF.MARCH..1888.I.WAS.RETURNING Original: One night-it was on the twentieth of March, 1888-I was returning Encoded: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
REXX
Extra coding was added to:
- allow the use of any table (specifiable on the invocation of the genCipher subroutine, the 5th line in the REXX program),
- no hard-coding of the location of blanks,
- no hard-coding or the numbered lines in the straddled checkerboard table,
- no hard-coding of the location of the escape character,
- support the usage of a blank in the 1st character (the top line of the table).
/*REXX program uses the straddling checkerboard cipher to encrypt/decrypt a message. */
parse arg msg /*obtain optional message from the C.L.*/
if msg='' then msg= 'One night-it was the twentieth of March, 1888-I was returning'
say 'plain text=' msg
call genCipher 'et aon ris', 'bcdfghjklm', 'pq/uvwxyz.' /*build the cipher (board)*/
enc= encrypt(msg); say ' encrypted=' enc /*encrypt message and show encryption. */
dec= decrypt(enc); say ' decrypted=' dec /*decrypt " " " decryption. */
exit 0 /*stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
genCipher: @.=; arg @..,two,three; z= -1; @.z= @.. /*build top row of cipher.*/
_= pos(' ', @.. ) - 1; @._= two /* " 2nd " " " */
_= pos(' ', @.., _+2) - 1; @._= three /* " 3rd " " " */
do j=0 for 9; @..= @.. || @.j /*construct a table for fast searching.*/
if @.j\=='' then @.r= @.r || j
_= pos('/', @.j) /*is the escape character in this row? */
if _\==0 then @.dig= j || (_-1) /*define " " for numerals.*/
end /*j*/
@..= space(@.., 0); return /*purify the table of encryptable chars*/
/*──────────────────────────────────────────────────────────────────────────────────────*/
encrypt: procedure expose @.; arg !,,$ /*$: output (encrypted text) so far.*/
do j=1 for length(!) /*process each of the plain─text chars.*/
x= substr(!, j, 1) /*obtain a message char to be encrypted*/
if datatype(x, 'W') then do; $= $ || @.dig || x; iterate; end /*numeral?*/
if pos(x, @..)==0 then iterate /*Not one of the allowable chars? Skip*/
do k=-1 for 10; y= pos(x, @.k) /*traipse thru rows, looking for match.*/
if y==0 then iterate /*Not in this row? Then keep looking.*/
z= k; if z==-1 then z= /*construct the index of the cypher row*/
$= $ || z || (y-1); leave /*add an encrypted character to output.*/
end /*k*/
end /*j*/; return $
/*──────────────────────────────────────────────────────────────────────────────────────*/
decrypt: procedure expose @.; parse arg !,,$ /*$: output (decrypted text) so far.*/
do j=1 to length(!); rw= -1 /*process each of the encypted numbers.*/
x= substr(!,j,1) /*obtain a message char to be decrypted*/
if substr(!,j,2)==@.dig then do; j= j+2; $= $ || substr(!, j, 1); iterate; end
if pos(x, @.r)\==0 then do; j= j+1; rw=x; x=substr(!, j, 1); end
$= $ || substr(@.rw, x+1, 1) /*add a character to decrypted message.*/
end /*j*/; return $
- output when using the default input:
plain text= One night-it was the twentieth of March, 1888-I was returning encrypted= 4505824251816539125016505180125423293721256216286286288653970163758524 decrypted= ONENIGHTITWASTHETWENTIETHOFMARCH1888IWASRETURNING
Ruby
class StraddlingCheckerboard
EncodableChars = "A-Z0-9."
SortedChars = " ./" + [*"A".."Z"].join
def initialize(board = nil)
if board.nil?
# create a new random board
rest = "BCDFGHJKLMPQUVWXYZ/.".chars.shuffle
@board = [" ESTONIAR".chars.shuffle, rest[0..9], rest[10..19]]
elsif board.chars.sort.join == SortedChars
@board = board.chars.each_slice(10).to_a
else
raise ArgumentError, "invalid #{self.class}: #{board}"
end
# find the indices of the first row blanks
@row_labels = @board[0].each_with_index.select {|v, i| v == " "}.map {|v,i| i}
@mapping = {}
@board[0].each_with_index {|char, idx| @mapping[char] = idx.to_s unless char == " "}
@board[1..2].each_with_index do |row, row_idx|
row.each_with_index do |char, idx|
@mapping[char] = "%d%d" % [@row_labels[row_idx], idx]
end
end
end
def encode(message)
msg = message.upcase.delete("^#{EncodableChars}")
msg.chars.inject("") do |crypt, char|
crypt << (char =~ /[0-9]/ ? @mapping["/"] + char : @mapping[char])
end
end
def decode(code)
msg = ""
tokens = code.chars
until tokens.empty?
token = tokens.shift
itoken = token.to_i
unless @row_labels.include?(itoken)
msg << @board[0][itoken]
else
token2 = tokens.shift
if @mapping["/"] == token + token2
msg << tokens.shift
else
msg << @board[1+@row_labels.index(itoken)][token2.to_i]
end
end
end
msg
end
def to_s
@board.inject("") {|res, row| res << row.join}
end
def inspect
"#<%s board=%p, row_labels=%p, mapping=%p>" % [self.class, to_s, @row_labels, @mapping]
end
end
The test suite
require 'test/unit'
class StraddlingCheckerboardTest < Test::Unit::TestCase
def setup
@msg = "One night-it was on the twentieth of March, 1888-I was returning"
@expected = "ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING"
end
def test1
sc = StraddlingCheckerboard.new "ET AON RISBCDFGHJKLMPQ/UVWXYZ."
code = sc.encode(@msg)
plaintext = sc.decode(code)
puts "using checkerboard: #{sc}"
puts "original: #{@msg}"
puts "encoded: #{code}"
puts "decoded: #{plaintext}"
assert_equal("450582425181653945125016505180125423293721256216286286288653970163758524", code)
assert_equal(@expected, plaintext)
end
def test_board_with_space_in_first_char
sc = StraddlingCheckerboard.new " RIOESN ATG./LXYBDKQMJUHWPVCFZ"
code = sc.encode(@msg)
plaintext = sc.decode(code)
#p sc
#puts "encoded: #{code}"
#puts "decoded: #{plaintext}"
assert_equal(@expected, plaintext)
end
def test_random_board
sc = StraddlingCheckerboard.new
plaintext = sc.decode(sc.encode(@msg))
assert_equal(@expected, plaintext)
end
def test_invalid_input
assert_raise(ArgumentError) {StraddlingCheckerboard.new "ET ON RISBCDFGHJKLMPQ/UVWXYZ.!"}
end
end
output
Run options: # Running tests: using checkerboard: ET AON RISBCDFGHJKLMPQ/UVWXYZ. original: One night-it was on the twentieth of March, 1888-I was returning encoded: 450582425181653945125016505180125423293721256216286286288653970163758524 decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING .... Finished tests in 0.007873s, 508.0378 tests/s, 635.0472 assertions/s. 4 tests, 5 assertions, 0 failures, 0 errors, 0 skips
Scala
- Output:
Best seen running in your browser either by ScalaFiddle (ES aka JavaScript, non JVM) or Scastie (remote JVM).
object StraddlingCheckerboard extends App {
private val dictonary = Map("H" -> "0", "O" -> "1",
"L" -> "2", "M" -> "4", "E" -> "5", "S" -> "6", "R" -> "8", "T" -> "9",
"A" -> "30", "B" -> "31", "C" -> "32", "D" -> "33", "F" -> "34", "G" -> "35",
"I" -> "36", "J" -> "37", "K" -> "38", "N" -> "39", "P" -> "70", "Q" -> "71",
"U" -> "72", "V" -> "73", "W" -> "74", "X" -> "75", "Y" -> "76", "Z" -> "77",
"." -> "78", "/" -> "79", "0" -> "790", "1" -> "791", "2" -> "792", "3" -> "793",
"4" -> "794", "5" -> "795", "6" -> "796", "7" -> "797", "8" -> "798", "9" -> "799")
private def encode(s: String) =
s.toUpperCase.map { case ch: Char => dictonary.getOrElse(ch.toString, "") }.mkString
private def decode(s: String) = {
val revDictionary: Map[String, String] = dictonary.map {case (k, v) => (v, k)}
val pat = "(79.|3.|7.|.)".r
pat.findAllIn(s).map { el => revDictionary.getOrElse(el, "")}.addString(new StringBuilder)
}
val enc = encode(
"One night-it was on the twentieth of March, " + "1888-I was returning"
)
println(enc)
println(decode(enc))
}
Tcl
Structured as a class, the instances of which contain encoding and decoding mappings suitable for use with Tcl's built in string remapping engine. This uses the fact that no sequence of digits in the encoded form that maps to one character is a prefix of the sequence for any other character. (Inspired by the description of the Raku solution.)
package require Tcl 8.6
oo::class create StraddlingCheckerboardCypher {
variable encmap decmap
constructor table {
# Sanity check the table
foreach ch [lindex $table 0] i {"" 0 1 2 3 4 5 6 7 8 9} {
if {$ch eq "" && $i ne "" && [lsearch -index 0 $table $i] < 1} {
error "bad checkerboard table"
}
}
# Synthesize the escaped number row
foreach row $table {
if {"/" ni $row} continue
set pfx [lindex $row 0][expr {[lsearch -exact $row "/"]-1}]
lappend table [list $pfx 0 1 2 3 4 5 6 7 8 9]
break
}
# Build the actual per-character mapping
foreach row $table {
foreach ch [lrange $row 1 end] n {0 1 2 3 4 5 6 7 8 9} {
if {$ch in {"" "/"}} continue; # Skip escape cases
lappend encmap $ch [lindex $row 0]$n
lappend decmap [lindex $row 0]$n $ch
}
}
}
# These methods just sanitize their input and apply the map
method encode msg {
string map $encmap [regsub -all {[^A-Z0-9.]} [string toupper $msg] ""]
}
method decode msg {
string map $decmap [regsub -all {[^0-9]} $msg ""]
}
}
Demonstration code:
StraddlingCheckerboardCypher create demo {
{{} E T {} A O N {} R I S}
{2 B C D F G H J K L M}
{6 P Q / U V W X Y Z .}
}
set input "One night-it was on the twentieth of March, 1888-I was returning"
set encrypted [demo encode $input]
set output [demo decode $encrypted]
puts "Input: $input"
puts "Encoded: $encrypted"
puts "Decoded: $output"
Output:
Input: One night-it was on the twentieth of March, 1888-I was returning Encoded: 450582425181653945125016505180125423293721256216286286288653970163758524 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
VBScript
' Straddling checkerboard - VBScript - 19/04/2019
Function encrypt(ByVal originalText, ByVal alphabet, blank1, blank2)
Const notEscape = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ."
Dim i, j, curChar, escChar, outText
Dim cipher 'Hash table
Set cipher = CreateObject("Scripting.Dictionary")
'build cipher reference
alphabet = UCase(alphabet) : j = 0
For i = 1 To 28
curChar = Mid(alphabet, i, 1)
Select Case True
Case i>= 1 And i<= 8
If j = blank1 Or j = blank2 Then j = j + 1 'adjust for blank
cipher.Add curChar, CStr(j)
j = j + 1
Case i>= 9 And i<=18
cipher.Add curChar, CStr(blank1) & CStr(i - 9)
Case i>=19 And i<=28
cipher.Add curChar, CStr(blank2) & CStr(i - 19)
End Select 'i
If InStr(notEscape, curChar) = 0 Then
escChar = curChar
'Wscript.Echo "escChar=" & escChar & " cipher(escChar)=" & cipher(escChar)
End If
Next 'i
For i = 0 To 9: cipher.Add CStr(i), cipher(escChar) & CStr(i): Next
'encrypt each character
originalText = UCase(originalText)
For i = 1 To Len(originalText)
outText = outText & cipher(Mid(originalText, i, 1))
Next
encrypt=outText
End Function 'encrypt
Function decrypt(ByVal cipherText, ByVal alphabet, blank1, blank2)
Const notEscape = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ."
Dim i, j, curChar, escCipher, outText
Dim cipher 'Hash table
Set cipher = CreateObject("Scripting.Dictionary")
'build decipher reference
alphabet = UCase(alphabet) : j = 0
For i = 1 To 28
curChar = Mid(alphabet, i, 1)
Select Case True
Case i>= 1 And i<= 8
If j = blank1 Or j = blank2 Then j = j + 1 'adjust for blank
cipher.Add CStr(j),curChar
j = j + 1
Case i>= 9 And i<=18
cipher.Add CStr(blank1) & CStr(i - 9), curChar
Case i>=19 And i<=28
cipher.Add CStr(blank2) & CStr(i - 19), curChar
End Select 'i
If InStr(notEscape, curChar) = 0 Then
'the last element of cipher
arrayKeys=cipher.keys
escCipher = arrayKeys(cipher.count-1)
'Wscript.Echo "escCipher=" & escCipher & " cipher(escCipher)=" & cipher(escCipher)
End If
Next 'i
For i = 0 To 9: cipher.Add escCipher & CStr(i), CStr(i): Next
'decrypt each character
i = 1
Do While i <= Len(cipherText)
curChar = Mid(cipherText, i, 1)
If curChar = CStr(blank1) Or curChar = CStr(blank2) Then
curChar = Mid(cipherText, i, 2)
If curChar = escCipher Then curChar = Mid(cipherText, i, 3)
End If
outText = outText & cipher(curChar)
i = i + Len(curChar)
Loop 'i
decrypt=outText
End Function 'decrypt
message = "One night-it was on the twentieth of March, 1888-I was returning"
cipher = "HOLMESRTABCDFGIJKNPQUVWXYZ./"
'3 7 <=8
'HOL MES RT
'ABCDFGIJKN
'PQUVWXYZ./
Buffer=Buffer & "Original: " & message & vbCrlf
encoded = encrypt(message, cipher, 3, 7)
Buffer=Buffer & "encoded: " & encoded & vbCrlf
decoded = decrypt(encoded, cipher, 3, 7)
Buffer=Buffer & "decoded: " & decoded & vbCrlf
Wscript.Echo Buffer
- Output:
Original: One night-it was on the twentieth of March, 1888-I was returning encoded: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
Wren
import "./str" for Str
var board = "ET AON RISBCDFGHJKLMPQ/UVWXYZ."
var digits = "0123456789"
var rows = " 26"
var escape = "62"
var key = "0452"
var encrypt = Fn.new { |message|
var msg = Str.upper(message).
where { |c| (board.contains(c) || digits.contains(c)) && !" /".contains(c) }.join()
var sb = ""
for (c in msg) {
var idx = board.indexOf(c)
if (idx > -1) {
var row = (idx/10).floor
var col = idx % 10
sb = sb + ((row == 0) ? "%(col)" : "%(rows[row])%(col)")
} else {
sb = sb + "%(escape)%(c)"
}
}
var enc = sb.bytes.toList
var i = 0
for (c in enc) {
var k = key[i%4].bytes[0] - 48
if (k != 0) {
var j = c - 48
enc[i] = 48 + ((j + k) % 10)
}
i = i + 1
}
return enc.map { |b| String.fromByte(b) }.join()
}
var decrypt = Fn.new { |encoded|
var enc = encoded.bytes.toList
var i = 0
for (c in enc) {
var k = key[i%4].bytes[0] - 48
if (k != 0) {
var j = c - 48
enc[i] = 48 + ((j >= k) ? (j - k) % 10 : (10 + j - k) % 10)
}
i = i + 1
}
var len = enc.count
var sb = ""
i = 0
while (i < len) {
var c = enc[i]
var idx = rows.indexOf((c-48).toString)
if (idx == -1) {
var idx2 = c - 48
sb = sb + board[idx2]
i = i + 1
} else if ("%(c-48)%(enc[i + 1]-48)" == escape) {
sb = sb + (enc[i + 2] - 48).toString
i = i + 3
} else {
var idx2 = idx * 10 + enc[i + 1] - 48
sb = sb + board[idx2]
i = i + 2
}
}
return sb
}
var messages = [
"Attack at dawn",
"One night-it was on the twentieth of March, 1888-I was returning",
"In the winter 1965/we were hungry/just barely alive",
"you have put on 7.5 pounds since I saw you.",
"The checkerboard cake recipe specifies 3 large eggs and 2.25 cups of flour."
]
for (message in messages) {
var encrypted = encrypt.call(message)
var decrypted = decrypt.call(encrypted)
System.print("\nMessage : %(message)")
System.print("Encrypted : %(encrypted)")
System.print("Decrypted : %(decrypted)")
}
- Output:
Message : Attack at dawn Encrypted : 3565257935743007 Decrypted : ATTACKATDAWN Message : One night-it was on the twentieth of March, 1888-I was returning Encrypted : 495786945533698149645468540384645875238925776668221480708005915367278976 Decrypted : ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING Message : In the winter 1965/we were hungry/just barely alive Encrypted : 89645417896270736648201450026959060839767024608116557470618482160 Decrypted : INTHEWINTER1965WEWEREHUNGRYJUSTBARELYALIVE Message : you have put on 7.5 pounds since I saw you. Encrypted : 61983605685800834914704829124087264189730245691940889 Decrypted : YOUHAVEPUTON7.5POUNDSSINCEISAWYOU. Message : The checkerboard cake recipe specifies 3 large eggs and 2.25 cups of flour. Encrypted : 160225770664742408892673362274738052905225343251668487244454469139746678907466041088039436848815704 Decrypted : THECHECKERBOARDCAKERECIPESPECIFIES3LARGEEGGSAND2.25CUPSOFFLOUR.
zkl
var [const]
val2key=Dictionary(
"A","30", "B","31", "C","32", "D","33", "E","5", "F","34", "G","35",
"H","0", "I","36", "J","37", "K","38", "L","2", "M","4", ".","78",
"N","39", "/","79", "O","1", "0","790", "P","70", "1","791", "Q","71",
"2","792", "R","8", "3","793", "S","6", "4","794" ,"T","9", "5","795",
"U","72", "6","796", "V","73", "7","797", "W","74", "8","798", "X","75",
"9","799", "Y","76", "Z","77"),
key2val=val2key.pump(Dictionary(),"reverse");
fcn encode(txt){ txt.toUpper().pump(String,val2key.find.fp1("")) }
fcn decode(str){ RegExp("79.|3.|7.|.").pump(str,String,key2val.get) }txt:="One night-it was on the twentieth of March, 1888-I was returning";
str:=encode(txt);
println("Encoded: ", str);
println("Decoded: ", decode(str));- Output:
ncoded: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING