Straddling checkerboard
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.
ALGOL 68
Note: This specimen retains the original C++ coding style.
<lang algol68>#!/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 ))
)</lang> Output:
Original: One night-it was on the twentieth of March, 1888-I was returning Encoded: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
AutoHotkey
<lang 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</lang>
C
<lang 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;
}</lang>
Shorter version
<lang C>#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;
}</lang>Output:<lang>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</lang>
C++
<lang cpp>#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; }
};</lang>
Test program: <lang cpp>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;
}</lang>
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: <lang d>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);
}</lang>
- Output:
Encoded: 139539363509369743061399059745399365901344308320791798798798367430685972839363935 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
Alternative version
Same output: <lang d>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));
}</lang>
Go
<lang 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
}</lang>
- Output:
you have put on 7.5 pounds since I saw you. 01306592038080673955702555083069056649578462090130602 YOUHAVEPUTON7.5POUNDSSINCEISAWYOU.
Icon and Unicon
<lang Icon>procedure main() StraddlingCheckerBoard("setup","HOLMESRTABCDFGIJKNPQUVWXYZ./", 3,7)
text := "One night. it was on the twentieth of March, 1888. I was returning" write("text = ",image(text)) write("encode = ",image(en := StraddlingCheckerBoard("encode",text))) write("decode = ",image(StraddlingCheckerBoard("decode",en))) end
procedure StraddlingCheckerBoard(act,text,b1,b2) static SCE,SCD case act of {
"setup" : { if (b1 < b2 < 10) & (*text = *cset(text) = 28) then { SCE := table("") SCD := table() esc := text[-1] # escape every text[(b1|b2)+1+:0] := " " # blanks uix := ["",b1,b2] # 1st position every c := text[1 + (i := 0 to *text-1)] do # build translation if c ~== " " then # skip blanks SCD[SCE[c] := SCE[map(c)] := uix[i/10+1]||(i%10) ] := c every c := !&digits do SCD[SCE[c] := SCE[esc] || c] := c delete(SCD,SCE[esc]) delete(SCE,esc) } else stop("Improper setup: ",image(text),", ",b1,", ",b2) } "encode" : { every (s := "") ||:= x := SCE[c := !text] return s } "decode" : { s := "" text ? until pos(0) do s ||:= \SCD[k := move(1 to 3)] return s } }
end</lang>
Output:
text = "One night. it was on the twentieth of March, 1888. I was returning" encode = "1395393635097836974306139905974539936590134430832079179879879878367430685972839363935" decode = "ONENIGHT.ITWASONTHETWENTIETHOFMARCH1888.IWASRETURNING"
J
Solution: <lang j>'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.
)</lang> Example usage: <lang j> 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</lang> Or using the rules proposed by Util on the discussion page: <lang j> 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</lang>
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: <lang j>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 )</lang>
Example usage: <lang j> 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</lang>
Java
<lang java>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(); }
}</lang>
139539363509369743061399059745399365901344308320791798798798367430685972839363935 ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING
JavaScript
<lang 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></lang>
Output:
One night-it was on the twentieth of March, 1888-I was returning. 34045747525284613427502840425027537379697175891898898898584619028294547488 ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING.
Perl 6
The .trans method in Perl 6 improves on Perl 5's tr/// by allowing multi-character translation tables.
We build the full table during .new, which simplifies .encode and .decode. <lang perl6>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 { say ~ .list for @!table };
method decode ( Str $s --> Str ) { $s.trans($!plain2code.invert); }
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 [~] './', '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: * // ' ' ], [ $u, @!flat_board[10 .. 19] ], [ $v, @!flat_board[20 .. 29] ];
my @order = 0..9; # This may be passed as a param in the future
my @nums = @order, @order.map({ +"$u$_" }), @order.map({ +"$v$_" });
my %p2c = @!flat_board Z=> @nums; %p2c.delete(Any); %p2c{$_} = %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"; }
}</lang>
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
PicoLisp
<lang 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)) ) ) ) ) )</lang>
Output:
: (straddle "One night-it was on the twentieth of March, 1888-I was returning") -> "139539363509369743061399059745399365901344308320791798798798367430685972839363935" : (unStraddle @) -> "ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING"
PureBasic
<lang 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</lang> 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: <lang python>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)))</lang> 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>#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))</lang>
Now we define the functions to straddle and unstraddle the message. <lang Racket>(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)))))</lang>
Two examples: <lang Racket>(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."))</lang>
- 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
Ruby
<lang 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</lang>
The test suite <lang ruby>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</lang>
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
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 Perl 6 solution.) <lang tcl>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 ""]
}
}</lang> Demonstration code: <lang tcl>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"</lang> Output:
Input: One night-it was on the twentieth of March, 1888-I was returning Encoded: 450582425181653945125016505180125423293721256216286286288653970163758524 Decoded: ONENIGHTITWASONTHETWENTIETHOFMARCH1888IWASRETURNING