Caesar cipher
Implement a Caesar cipher, both encoding and decoding.
The key is an integer from 1 to 25.
You are encouraged to solve this task according to the task description, using any language you may know.
- Task
This cipher rotates (either towards left or right) the letters of the alphabet (A to Z).
The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A).
So key 2 encrypts "HI" to "JK", but key 20 encrypts "HI" to "BC".
This simple "mono-alphabetic substitution cipher" provides almost no security, because an attacker who has the encoded message can either use frequency analysis to guess the key, or just try all 25 keys.
Caesar cipher is identical to Vigenère cipher with a key of length 1.
Also, Rot-13 is identical to Caesar cipher with key 13.
- Related tasks
11l
<lang 11l>F caesar(string, =key, decode = 0B)
I decode
key = 26 - key
V r = ‘ ’ * string.len
L(c) string
r[L.index] = S c
‘a’..‘z’
Char(code' (c.code - ‘a’.code + key) % 26 + ‘a’.code)
‘A’..‘Z’
Char(code' (c.code - ‘A’.code + key) % 26 + ‘A’.code)
E
c
R r
V msg = ‘The quick brown fox jumped over the lazy dogs’ print(msg) V enc = caesar(msg, 11) print(enc) print(caesar(enc, 11, decode' 1B))</lang>
- Output:
The quick brown fox jumped over the lazy dogs Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozrd The quick brown fox jumped over the lazy dogs
360 Assembly
A good example of the use of TR instruction to translate a character. <lang 360asm>* Caesar cypher 04/01/2019 CAESARO PROLOG
XPRNT PHRASE,L'PHRASE print phrase
LH R3,OFFSET offset
BAL R14,CYPHER call cypher
LNR R3,R3 -offset
BAL R14,CYPHER call cypher
EPILOG
CYPHER LA R4,REF(R3) @ref+offset
MVC A,0(R4) for A to I
MVC J,9(R4) for J to R
MVC S,18(R4) for S to Z
TR PHRASE,TABLE translate
XPRNT PHRASE,L'PHRASE print phrase
BR R14 return
OFFSET DC H'22' between -25 and +25 PHRASE DC CL37'THE FIVE BOXING WIZARDS JUMP QUICKLY'
DC CL26'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
REF DC CL26'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
DC CL26'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
TABLE DC CL256' ' translate table for TR
ORG TABLE+C'A'
A DS CL9
ORG TABLE+C'J'
J DS CL9
ORG TABLE+C'S'
S DS CL8
ORG
YREGS
END CAESARO</lang>
- Output:
THE FIVE BOXING WIZARDS JUMP QUICKLY PDA BERA XKTEJC SEVWNZO FQIL MQEYGHU THE FIVE BOXING WIZARDS JUMP QUICKLY
8th
<lang forth>\ Ensure the output char is in the correct range:
- modulate \ char base -- char
tuck n:- 26 n:+ 26 n:mod n:+ ;
\ Symmetric Caesar cipher. Input is text and number of characters to advance \ (or retreat, if negative). That value should be in the range 1..26
- caesar \ intext key -- outext
>r
(
\ Ignore anything below '.' as punctuation:
dup '. n:> if
\ Do the conversion
dup r@ n:+ swap
\ Wrap appropriately
'A 'Z between if 'A else 'a then modulate
then
) s:map rdrop ;
"The five boxing wizards jump quickly!" dup . cr 1 caesar dup . cr -1 caesar . cr bye</lang>
- Output:
The five boxing wizards jump quickly! Uif gjwf cpyjoh xjabset kvnq rvjdlmz! The five boxing wizards jump quickly!
Action!
<lang Action!>CHAR FUNC Shift(CHAR c BYTE code)
CHAR base
IF c>='a AND c<='z THEN base='a ELSEIF c>='A AND c<='Z THEN base='A ELSE RETURN (c) FI c==+code-base c==MOD 26
RETURN (c+base)
PROC Encrypt(CHAR ARRAY in,out BYTE code)
INT i
out(0)=in(0) FOR i=1 TO in(0) DO out(i)=Shift(in(i),code) OD
RETURN
PROC Decrypt(CHAR ARRAY in,out BYTE code)
Encrypt(in,out,26-code)
RETURN
PROC Test(CHAR ARRAY in BYTE code)
CHAR ARRAY enc(256),dec(256)
PrintE("Original:") PrintE(in)
Encrypt(in,enc,code)
PrintF("Encrypted code=%B:%E",code) PrintE(enc)
Decrypt(enc,dec,code)
PrintF("Decrypted code=%B:%E",code) PrintE(dec)
PutE()
RETURN
PROC Main()
Test("The quick brown fox jumps over the lazy dog.",23)
Test("The quick brown fox jumps over the lazy dog.",5)
RETURN</lang>
- Output:
Screenshot from Atari 8-bit computer
Original: The quick brown fox jumps over the lazy dog. Encrypted code=23: Qeb nrfzh yoltk clu grjmp lsbo qeb ixwv ald. Decrypted code=23: The quick brown fox jumps over the lazy dog. Original: The quick brown fox jumps over the lazy dog. Encrypted code=5: Ymj vznhp gwtbs ktc ozrux tajw ymj qfed itl. Decrypted code=5: The quick brown fox jumps over the lazy dog.
Ada
<lang Ada>with Ada.Text_IO;
procedure Caesar is
type modulo26 is modulo 26;
function modulo26 (Character: Character; Output: Character) return modulo26 is
begin
return modulo26 (Character'Pos(Character)+Character'Pos(Output));
end modulo26;
function Character(Val: in modulo26; Output: Character)
return Character is
begin
return Character'Val(Integer(Val)+Character'Pos(Output));
end Character;
function crypt (Playn: String; Key: modulo26) return String is
Ciph: String(Playn'Range);
begin
for I in Playn'Range loop
case Playn(I) is
when 'A' .. 'Z' =>
Ciph(I) := Character(modulo26(Playn(I)+Key), 'A');
when 'a' .. 'z' =>
Ciph(I) := Character(modulo26(Playn(I)+Key), 'a');
when others =>
Ciph(I) := Playn(I);
end case;
end loop;
return Ciph;
end crypt;
Text: String := Ada.Text_IO.Get_Line; Key: modulo26 := 3; -- Default key from "Commentarii de Bello Gallico" shift cipher
begin -- encryption main program
Ada.Text_IO.Put_Line("Playn ------------>" & Text);
Text := crypt(Text, Key);
Ada.Text_IO.Put_Line("Ciphertext ----------->" & Text);
Ada.Text_IO.Put_Line("Decrypted Ciphertext ->" & crypt(Text, -Key));
end Caesar;</lang>
- Output:
> ./caesar The five boxing wizards jump quickly Plaintext ------------>The five boxing wizards jump quickly Ciphertext ----------->Wkh ilyh eralqj zlcdugv mxps txlfnob Decrypted Ciphertext ->The five boxing wizards jump quickly
ALGOL 68
<lang algol68>#!/usr/local/bin/a68g --script #
program caesar: BEGIN
MODE MODXXVI = SHORT SHORT INT; # MOD26 #
PROC to m26 = (CHAR c, offset)MODXXVI:
BEGIN
ABS c - ABS offset
END #to m26#;
PROC to char = (MODXXVI value, CHAR offset)CHAR:
BEGIN
REPR ( ABS offset + value MOD 26 )
END #to char#;
PROC encrypt = (STRING plain, MODXXVI key)STRING:
BEGIN
[UPB plain]CHAR ciph;
FOR i TO UPB plain DO
CHAR c = plain[i];
ciph[i]:=
IF "A" <= c AND c <= "Z" THEN
to char(to m26(c, "A")+key, "A")
ELIF "a" <= c AND c <= "z" THEN
to char(to m26(c, "a")+key, "a")
ELSE
c
FI
OD;
ciph
END #encrypt#;
- caesar main program #
STRING text := "The five boxing wizards jump quickly" # OR read string #; MODXXVI key := 3; # Default key from "Bello Gallico" #
printf(($gl$, "Plaintext ------------>" + text)); text := encrypt(text, key); printf(($gl$, "Ciphertext ----------->" + text)); printf(($gl$, "Decrypted Ciphertext ->" + encrypt(text, -key)))
END #caesar#</lang>
- Output:
Plaintext ------------>The five boxing wizards jump quickly Ciphertext ----------->Wkh ilyh eralqj zlcdugv mxps txlfnob Decrypted Ciphertext ->The five boxing wizards jump quickly
APL
<lang apl>
∇CAESAR[⎕]∇ ∇
[0] A←K CAESAR V [1] A←'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz' [2] ((,V∊A)/,V)←A[⎕IO+52|(2×K)+((A⍳,V)-⎕IO)~52] [3] A←V
∇
</lang>
- Output:
6 CAESAR ⎕←TEXT_MATRIX
This method uses selective specification
(similar to pattern matching in Haskell)
to modify only alphabetic characters.
Znoy skznuj ayky ykrkizobk yvkioloigzout
(yosorgx zu vgzzkxt sgzinotm ot Ngyqkrr)
zu sujole utre grvnghkzoi ingxgizkxy.
¯1 CAESAR ⎕←ENCRYPTED
Ofhbujwf lfzt (efdszqujoh) xpslt: IBM 9000
Negative keys (decrypting) works: HAL 9000
¯1.5 CAESAR ⎕←CAPSLOCK
fUN FACT: FRACTIONAL KEYS SWITCH FROM upper case TO LOWER CASE.
Esl dyar: dpyargmlyj icwq qugraf dpmk TOODQ BZRD rm jmucp ayqc.
AppleScript
<lang applescript>(* Only non-accented English letters are altered here. *)
on caesarDecipher(txt, |key|)
return caesarEncipher(txt, -|key|)
end caesarDecipher
on caesarEncipher(txt, |key|)
set codePoints to id of txt
set keyPlus25 to |key| mod 26 + 25
repeat with thisCode in codePoints
tell thisCode mod 32
if ((it < 27) and (it > 0) and (thisCode div 64 is 1)) then ¬
set thisCode's contents to thisCode - it + (it + keyPlus25) mod 26 + 1
end tell
end repeat
return string id codePoints
end caesarEncipher
-- Test code: set txt to "ROMANES EUNT DOMUS! The quick brown fox jumps over the lazy dog." set |key| to 9
set enciphered to caesarEncipher(txt, |key|) set deciphered to caesarDecipher(enciphered, |key|) return "Text: '" & txt & ("'" & linefeed & "Key: " & |key| & linefeed & linefeed) & (enciphered & linefeed & deciphered)</lang>
- Output:
<lang applescript>"Text: 'ROMANES EUNT DOMUS! The quick brown fox jumps over the lazy dog.' Key: 9
AXVJWNB NDWC MXVDB! Cqn zdrlt kaxfw oxg sdvyb xena cqn ujih mxp. ROMANES EUNT DOMUS! The quick brown fox jumps over the lazy dog."</lang>
Applesoft BASIC
<lang ApplesoftBasic>100 INPUT ""; T$
110 LET K% = RND(1) * 25 + 1 120 PRINT "ENCODED WITH "; 130 GOSUB 200ENCODED
140 LET K% = 26 - K% 150 PRINT "DECODED WITH "; 160 GOSUB 200DECODED
170 END
REM ENCODED/DECODED 200 PRINT "CAESAR " K%; 210 LET K$(1) = " (ROT-13)" 220 PRINT K$(K% = 13) 230 GOSUB 300CAESAR 240 PRINT T$ 250 RETURN
REM CAESAR T$ K% 300 FOR I = 1 TO LEN(T$) 310 LET C$ = MID$(T$, I, 1) 320 GOSUB 400ENCODE 330 LET L = I - 1 340 LET T$(0) = MID$(T$, 1, L) 350 LET L = I + 1 360 LET T$ = C$ + MID$(T$, L) 370 LET T$ = T$(0) + T$ 380 NEXT I 390 RETURN
REM ENCODE C$ K% 400 LET C = ASC(C$) 410 LET L = (C > 95) * 32 420 LET C = C - L 430 IF C < 65 THEN RETURN 440 IF C > 90 THEN RETURN 450 LET C = C + K% 460 IF C > 90 THEN C = C - 26 470 LET C$ = CHR$(C + L) 480 RETURN</lang>
- Output:
]RUN The quick brown fox jumps over the lazy dog. ENCODED WITH CAESAR 12 Ftq cguow ndaiz raj vgybe ahqd ftq xmlk pas. DECODED WITH CAESAR 14 The quick brown fox jumps over the lazy dog. ]?RND(-6):RUN 4.48226274E-08 PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS ENCODED WITH CAESAR 13 (ROT-13) CNPX ZL OBK JVGU SVIR QBMRA YVDHBE WHTF DECODED WITH CAESAR 13 (ROT-13) PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS ]K%=1:GOTO120 ENCODED WITH CAESAR 1 QBDL NZ CPY XJUI GJWF EPAFO MJRVPS KVHT DECODED WITH CAESAR 25 PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS
Arc
<lang Arc> (= rot (fn (L N)
(if
(and (<= 65 L) (>= 90 L))
(do
(= L (- L 65))
(= L (mod (+ N L) 26))
(= L (+ L 65)))
(and (<= 97 L) (>= 122 L))
(do
(= L (- L 97))
(= L (mod (+ N L) 26))
(= L (+ L 97))))
L))
(= caesar (fn (text (o shift))
(unless shift (= shift 13)) (= output (map [int _] (coerce text 'cons))) (= output (map [rot _ shift] output)) (string output) ))
</lang>
- Output:
<lang arc> (caesar "The quick brown fox jumps over the lazy dog.") "Gur dhvpx oebja sbk whzcf bire gur ynml qbt." </lang>
ARM Assembly
<lang ARM Assembly> /* ARM assembly Raspberry PI */ /* program caresarcode.s */
/* Constantes */ .equ STDOUT, 1 @ Linux output console .equ EXIT, 1 @ Linux syscall .equ WRITE, 4 @ Linux syscall
.equ STRINGSIZE, 500
/* Initialized data */ .data szMessString: .asciz "String :\n" szMessEncrip: .asciz "\nEncrypted :\n" szMessDecrip: .asciz "\nDecrypted :\n" szString1: .asciz "Why study medicine because there is internet ?"
szCarriageReturn: .asciz "\n"
/* UnInitialized data */ .bss szString2: .skip STRINGSIZE szString3: .skip STRINGSIZE /* code section */ .text .global main main:
ldr r0,iAdrszMessString @ display message bl affichageMess ldr r0,iAdrszString1 @ display string bl affichageMess ldr r0,iAdrszString1 ldr r1,iAdrszString2 mov r2,#20 @ key bl encrypt ldr r0,iAdrszMessEncrip bl affichageMess ldr r0,iAdrszString2 @ display string bl affichageMess ldr r0,iAdrszString2 ldr r1,iAdrszString3 mov r2,#20 @ key bl decrypt ldr r0,iAdrszMessDecrip bl affichageMess ldr r0,iAdrszString3 @ display string bl affichageMess ldr r0,iAdrszCarriageReturn bl affichageMess
100: @ standard end of the program
mov r0, #0 @ return code mov r7, #EXIT @ request to exit program svc 0 @ perform system call
iAdrszMessString: .int szMessString iAdrszMessDecrip: .int szMessDecrip iAdrszMessEncrip: .int szMessEncrip iAdrszString1: .int szString1 iAdrszString2: .int szString2 iAdrszString3: .int szString2 iAdrszCarriageReturn: .int szCarriageReturn /******************************************************************/ /* encrypt strings */ /******************************************************************/ /* r0 contains the address of the string1 */ /* r1 contains the address of the encrypted string */ /* r2 contains the key (1-25) */ encrypt:
push {r3,r4,lr} @ save registers
mov r3,#0 @ counter byte string 1
1:
ldrb r4,[r0,r3] @ load byte string 1 cmp r4,#0 @ zero final ? streqb r4,[r1,r3] moveq r0,r3 beq 100f cmp r4,#65 @ < A ? strltb r4,[r1,r3] addlt r3,#1 blt 1b cmp r4,#90 @ > Z bgt 2f add r4,r2 @ add key cmp r4,#90 @ > Z subgt r4,#26 strb r4,[r1,r3] add r3,#1 b 1b
2:
cmp r4,#97 @ < a ? strltb r4,[r1,r3] addlt r3,#1 blt 1b cmp r4,#122 @> z strgtb r4,[r1,r3] addgt r3,#1 bgt 1b add r4,r2 cmp r4,#122 subgt r4,#26 strb r4,[r1,r3] add r3,#1 b 1b
100:
pop {r3,r4,lr} @ restaur registers
bx lr @ return
/******************************************************************/ /* decrypt strings */ /******************************************************************/ /* r0 contains the address of the encrypted string1 */ /* r1 contains the address of the decrypted string */ /* r2 contains the key (1-25) */ decrypt:
push {r3,r4,lr} @ save registers
mov r3,#0 @ counter byte string 1
1:
ldrb r4,[r0,r3] @ load byte string 1 cmp r4,#0 @ zero final ? streqb r4,[r1,r3] moveq r0,r3 beq 100f cmp r4,#65 @ < A ? strltb r4,[r1,r3] addlt r3,#1 blt 1b cmp r4,#90 @ > Z bgt 2f sub r4,r2 @ substract key cmp r4,#65 @ < A addlt r4,#26 strb r4,[r1,r3] add r3,#1 b 1b
2:
cmp r4,#97 @ < a ? strltb r4,[r1,r3] addlt r3,#1 blt 1b cmp r4,#122 @ > z strgtb r4,[r1,r3] addgt r3,#1 bgt 1b sub r4,r2 @ substract key cmp r4,#97 @ < a addlt r4,#26 strb r4,[r1,r3] add r3,#1 b 1b
100:
pop {r3,r4,lr} @ restaur registers
bx lr @ return
/******************************************************************/ /* display text with size calculation */ /******************************************************************/ /* r0 contains the address of the message */ affichageMess:
push {r0,r1,r2,r7,lr} @ save registers
mov r2,#0 @ counter length */
1: @ loop length calculation
ldrb r1,[r0,r2] @ read octet start position + index
cmp r1,#0 @ if 0 its over
addne r2,r2,#1 @ else add 1 in the length
bne 1b @ and loop
@ so here r2 contains the length of the message
mov r1,r0 @ address message in r1
mov r0,#STDOUT @ code to write to the standard output Linux
mov r7, #WRITE @ code call system "write"
svc #0 @ call system
pop {r0,r1,r2,r7,lr} @ restaur registers
bx lr @ return
</lang>
Arturo
<lang rebol>ia: to :integer `a` iA: to :integer `A` lowAZ: `a`..`z` uppAZ: `A`..`Z`
caesar: function [s, xx][
k: (not? null? attr 'decode)? -> 26-xx -> xx
result: new ""
loop s 'i [
(in? i lowAZ)? -> 'result ++ to :char ia + (k + (to :integer i) - ia) % 26
[
(in? i uppAZ)? -> 'result ++ to :char iA + (k + (to :integer i) - iA) % 26
-> 'result ++ i
]
]
return result
]
msg: "The quick brown fox jumped over the lazy dogs" print ["Original :" msg] enc: caesar msg 11 print [" Encoded :" enc] print [" Decoded :" caesar.decode enc 11]</lang>
- Output:
Original : The quick brown fox jumped over the lazy dogs Encoded : Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozrd Decoded : The quick brown fox jumped over the lazy dogs
Astro
<lang python>fun caesar(s, k, decode: false):
if decode:
k = 26 - k
result =
for i in s.uppercase() where 65 <= ord(i) <= 90:
result.push! char(ord(i) - 65 + k) mod 26 + 65
return result
let message = "The quick brown fox jumped over the lazy dogs" let encrypted = caesar(msg, 11) let decrypted = caesar(enc, 11, decode: true)
print(message, encrypted, decrypted, sep: '\n')</lang>
AutoHotkey
This ungodly solution is an attempt at code-golf. It requires input to be all-caps alphabetic, only works on AutoHotkey_L Unicode, and might not run on x64 <lang AutoHotkey>n=2 s=HI t:=&s While *t o.=Chr(Mod(*t-65+n,26)+65),t+=2 MsgBox % o</lang> This next one is much more sane and handles input very well, including case. <lang AutoHotkey>Caesar(string, n){ Loop Parse, string { If (Asc(A_LoopField) >= Asc("A") and Asc(A_LoopField) <= Asc("Z")) out .= Chr(Mod(Asc(A_LoopField)-Asc("A")+n,26)+Asc("A")) Else If (Asc(A_LoopField) >= Asc("a") and Asc(A_LoopField) <= Asc("z")) out .= Chr(Mod(Asc(A_LoopField)-Asc("a")+n,26)+Asc("a")) Else out .= A_LoopField } return out }
MsgBox % Caesar("h i", 2) "`n" Caesar("Hi", 20)</lang>
- Output:
j k Bc
AutoIt
The Ceasar Funktion can enrcypt and decrypt, standart is Encryption, to Decrypt set third parameter to False <lang autoit> $Caesar = Caesar("Hi", 2, True) MsgBox(0, "Caesar", $Caesar) Func Caesar($String, $int, $encrypt = True) If Not IsNumber($int) Or Not StringIsDigit($int) Then Return SetError(1, 0, 0) If $int < 1 Or $int > 25 Then Return SetError(2, 0, 0) Local $sLetters, $x $String = StringUpper($String) $split = StringSplit($String, "") For $i = 1 To $split[0] If Asc($split[$i]) - 64 > 26 Or Asc($split[$i]) - 64 < 1 Then $sLetters &= $split[$i] ContinueLoop EndIf If $encrypt = True Then $move = Asc($split[$i]) - 64 + $int Else $move = Asc($split[$i]) - 64 - $int EndIf If $move > 26 Then $move -= 26 ElseIf $move < 1 Then $move += 26 EndIf While $move $x = Mod($move, 26) If $x = 0 Then $x = 26 $sLetters &= Chr($x + 64) $move = ($move - $x) / 26 WEnd Next Return $sLetters EndFunc ;==>Caesar </lang>
AWK
<lang awk>
- !/usr/bin/awk -f
BEGIN {
message = "My hovercraft is full of eels." key = 1
cypher = caesarEncode(key, message) clear = caesarDecode(key, cypher)
print "message: " message print " cypher: " cypher print " clear: " clear exit
}
function caesarEncode(key, message) {
return caesarXlat(key, message, "encode")
}
function caesarDecode(key, message) {
return caesarXlat(key, message, "decode")
}
function caesarXlat(key, message, dir, plain, cypher, i, num, s) {
plain = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" cypher = substr(plain, key+1) substr(plain, 1, key)
if (toupper(substr(dir, 1, 1)) == "D") {
s = plain
plain = cypher
cypher = s
}
s = ""
message = toupper(message)
for (i = 1; i <= length(message); i++) {
num = index(plain, substr(message, i, 1))
if (num) s = s substr(cypher, num, 1)
else s = s substr(message, i, 1)
}
return s
} </lang>
- Output:
message: My hovercraft is full of eels. cypher: NZ IPWFSDSBGU JT GVMM PG FFMT. clear: MY HOVERCRAFT IS FULL OF EELS.
Babel
<lang babel>((main
{"The quick brown fox jumps over the lazy dog.\n"
dup <<
17 caesar_enc ! dup <<
17 caesar_dec ! <<})
(caesar_enc
{ 2 take
{ caesar_enc_loop ! }
nest })
(caesar_enc_loop {
give
<- str2ar
{({ dup is_upper ! }
{ 0x40 -
-> dup <-
encrypt !
0x40 + }
{ dup is_lower ! }
{ 0x60 -
-> dup <-
encrypt !
0x60 + }
{ 1 }
{fnord})
cond}
eachar
collect !
ls2lf ar2str})
(collect { -1 take })
(encrypt { + 1 - 26 % 1 + })
(caesar_dec { <- 26 -> - caesar_enc ! })
(is_upper
{ dup
<- 0x40 cugt ->
0x5b cult
cand })
(is_lower
{ dup
<- 0x60 cugt ->
0x7b cult
cand }))</lang>
- Output:
The quick brown fox jumps over the lazy dog. Kyv hlztb sifne wfo aldgj fmvi kyv crqp ufx. The quick brown fox jumps over the lazy dog.
BaCon
<lang qbasic>CONST lc$ = "abcdefghijklmnopqrstuvwxyz" CONST uc$ = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
CONST txt$ = "The quick brown fox jumps over the lazy dog."
FUNCTION Ceasar$(t$, k)
lk$ = MID$(lc$ & lc$, k+1, 26) uk$ = MID$(uc$ & uc$, k+1, 26)
RETURN REPLACE$(t$, lc$ & uc$, lk$ & uk$, 2)
END FUNCTION
tokey = RANDOM(25)+1 PRINT "Encrypting text with key: ", tokey
en$ = Ceasar$(txt$, tokey)
PRINT "Encrypted: ", en$ PRINT "Decrypted: ", Ceasar$(en$, 26-tokey)</lang>
- Output:
user@host $ bacon ceasar Converting 'ceasar.bac'... done, 20 lines were processed in 0.015 seconds. Compiling 'ceasar.bac'... cc -c ceasar.bac.c cc -o ceasar ceasar.bac.o -lbacon -lm Done, program 'ceasar' ready. user@host $ ./ceasar Encrypting text with key: 23 Encrypted: Qeb nrfzh yoltk clu grjmp lsbo qeb ixwv ald. Decrypted: The quick brown fox jumps over the lazy dog.
bash
Caesar cipher bash implementation
<lang bash> caesar_cipher() {
# michaeltd 2019-11-30 # https://en.wikipedia.org/wiki/Caesar_cipher # E n ( x ) = ( x + n ) mod 26. # D n ( x ) = ( x − n ) mod 26.
local -a _ABC=( "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R" "S" "T" "U" "V" "W" "X" "Y" "Z" ) local -a _abc=( "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z" )
local _out
if (( $# < 3 )) || "$1" != "-e" && "$1" != "-d" || (( $2 < 1 || $2 > 25 )); then echo "Usage: ${FUNCNAME[0]} -e|-d rotation (1-25) argument[(s)...]" >&2 return 1 fi
_func="${1}"; shift
_rotval="${1}"; shift
while [[ -n "${1}" ]]; do
for (( i = 0; i < ${#1}; i++ )); do
for (( x = 0; x < ${#_abc[*]}; x++ )); do
case "${_func}" in
"-e")
[[ "${1:$i:1}" == "${_ABC[$x]}" ]] && _out+="${_ABC[(( ( x + _rotval ) % 26 ))]}" && break
[[ "${1:$i:1}" == "${_abc[$x]}" ]] && _out+="${_abc[(( ( x + _rotval ) % 26 ))]}" && break;;
"-d")
[[ "${1:$i:1}" == "${_ABC[$x]}" ]] && _out+="${_ABC[(( ( x - _rotval ) % 26 ))]}" && break
[[ "${1:$i:1}" == "${_abc[$x]}" ]] && _out+="${_abc[(( ( x - _rotval ) % 26 ))]}" && break;;
esac
# If char has not been found by now lets add it as is.
(( x == ${#_abc[*]} - 1 )) && _out+="${1:$i:1}"
done
done
_out+=" "
shift
done
echo "${_out[*]}"
}
</lang>
- Output:
(input
Uryyb Jbeyq!
- Output:
(input
Hello World!
BASIC256
<lang>
- Caeser Cipher
- basic256 1.1.4.0
dec$ = "" type$ = "cleartext "
input "If decrypting enter " + "<d> " + " -- else press enter > ",dec$ # it's a klooj I know... input "Enter offset > ", iOffset
if dec$ = "d" then
iOffset = 26 - iOffset type$ = "ciphertext "
end if
input "Enter " + type$ + "> ", str$
str$ = upper(str$) # a bit of a cheat really, however old school encryption is always upper case len = length(str$)
for i = 1 to len
iTemp = asc(mid(str$,i,1))
if iTemp > 64 AND iTemp < 91 then
iTemp = ((iTemp - 65) + iOffset) % 26
print chr(iTemp + 65);
else
print chr(iTemp);
end if
next i </lang>
- Output:
Enter offset > 21 Enter cleartext > My hovercraft is full of eels. HT CJQZMXMVAO DN APGG JA ZZGN. Enter offset > 21 Enter ciphertext > HT CJQZMXMVAO DN APGG JA ZZGN. MY HOVERCRAFT IS FULL OF EELS.
BBC BASIC
<lang bbcbasic> plaintext$ = "Pack my box with five dozen liquor jugs"
PRINT plaintext$
key% = RND(25)
cyphertext$ = FNcaesar(plaintext$, key%)
PRINT cyphertext$
decyphered$ = FNcaesar(cyphertext$, 26-key%)
PRINT decyphered$
END
DEF FNcaesar(text$, key%)
LOCAL I%, C%
FOR I% = 1 TO LEN(text$)
C% = ASC(MID$(text$,I%))
IF (C% AND &1F) >= 1 AND (C% AND &1F) <= 26 THEN
C% = (C% AND &E0) OR (((C% AND &1F) + key% - 1) MOD 26 + 1)
MID$(text$, I%, 1) = CHR$(C%)
ENDIF
NEXT
= text$
</lang>
- Output:
Pack my box with five dozen liquor jugs Zkmu wi lyh gsdr psfo nyjox vsaeyb teqc Pack my box with five dozen liquor jugs
Beads
<lang Beads>beads 1 program 'Caesar cipher' calc main_init var str = "The five boxing wizards (🤖) jump quickly." log "Plain: {str}" str = Encrypt(str, 3) log "Encrypted: {str}" str = Decrypt(str, 3) log "Decrypted: {str}"
// encrypt a string by shifting the letters over by a number of slots // pass through any characters that are not in the Roman alphabet calc Encrypt( input:str --- string to encrypt nshift --- number of characters to slide over ) : str --- encrypted string
var newStr = "" loop from:1 to:str_len(input) count:myCount var unicode : num = from_char(subset(input, from:myCount, len:1)) if unicode >= 65 and unicode <= 90 unicode = mod((unicode - 65 + nshift), 26) + 65 elif unicode >= 97 and unicode <= 122 unicode = mod((unicode - 97 + nshift), 26) + 97 newStr = newStr & to_char(unicode) return newStr
// undo the encryption calc Decrypt( input:str nshift ) : str // we could also just shift by 26-nshift, same as going in reverse return Encrypt(input, -nshift)</lang>
- Output:
Plain: The five boxing wizards (🤖) jump quickly. Encrypted: Wkh ilyh eralqj zlcdugv (🤖) mxps txlfnob. Decrypted: The five boxing wizards (🤖) jump quickly.
Befunge
Almost direct copy of the Vigenère cipher, although the code has been reversed and the first line eliminated because of the simpler key initialisation.
The text to encrypt is read from stdin, and the key is the first integer on the stack - 11 (65+) in the example below.
<lang befunge>65+>>>>10p100p1>:v:+>#*,#g1#0-#0:#!<< "`"::_@#!`\*84:<~<$<^+"A"%*2+9<v"{"\`
- -"A"-::0\`\55*`+#^_\0g+"4"+4^>\`*48</lang>
- Output:
The quick brown fox jumped over the lazy dogs ESPBFTNVMCZHYQZIUFXAPOZGPCESPWLKJOZRD
The decrypter is essentially identical, except for a change of sign on the last line.
<lang befunge>65+>>>>10p100p1>:v:+>#*,#g1#0-#0:#!<< "`"::_@#!`\*84:<~<$<^+"A"%*2+9<v"{"\`
- -"A"-::0\`\55*`+#^_\0g-"4"+4^>\`*48</lang>
- Output:
ESPBFTNVMCZHYQZIUFXAPOZGPCESPWLKJOZRD THEQUICKBROWNFOXJUMPEDOVERTHELAZYDOGS
BQN
<lang bqn>o ← @‿'A'‿@‿'a'‿@ ⋄ m ← 5⥊↕2 ⋄ p ← m⊏∞‿26 Rot ← {i←⊑"A[a{"⍋𝕩 ⋄ i⊑o+p|(𝕨×m)+𝕩-o}⎉0</lang>
Example:
<lang bqn>3 Rot "We're no strangers to love // You know the rules and so do I"</lang>
"Zh'uh qr vwudqjhuv wr oryh // Brx nqrz wkh uxohv dqg vr gr L"
Brainf***
<lang bf> Author: Ettore Forigo | Hexwell
+ start the key input loop [
memory: | c | 0 | cc | key |
^
, take one character of the key
:c : condition for further ifs
!= ' ' (subtract 32 (ascii for ' '))
--------------------------------
(testing for the condition deletes it so duplication is needed) [>>+<+<-] duplicate > | [<+>-] | > | :cc : copy of :c
[ if :cc
|
> | :key : already converted digits
|
[>++++++++++<-] | multiply by 10
> | |
[<+>-] | |
< | |
|
< | :cc
[-] | clear (making the loop an if)
] |
<< :c
[>>+<+<-] duplicate > | [<+>-] | > | :cc
[ if :cc
---------------- | subtract 16 (difference between ascii for ' ' (already subtracted before) and ascii for '0'
| making '0' 0; '1' 1; etc to transform ascii to integer)
|
[>+<-] | move/add :cc to :key
] |
<< :c
]
memory: | 0 | 0 | 0 | key |
^
>>> :key
[<<<+>>>-] move key
memory: | key | 0 | 0 | 0 |
^
< ^ + start the word input loop [
memory: | key | 0 | c | 0 | cc |
^
, take one character of the word
:c : condition for further if
!= ' ' (subtract 32 (ascii for ' '))
--------------------------------
[>>+<+<-] duplicate > | [<+>-] | > | :cc : copy of :c
[ if :cc
| subtract 65 (difference between ascii for ' ' (already subtracted before) and ascii for 'a'; making a 0; b 1; etc)
-----------------------------------------------------------------
|
<<<< | :key
|
[>>>>+<<<+<-] | add :key to :cc := :shifted
> | |
[<+>-] | |
|
| memory: | key | 0 | c | 0 | cc/shifted | 0 | 0 | 0 | 0 | 0 | divisor |
| ^
|
>>>>>>>>> | :divisor
++++++++++++++++++++++++++ | = 26
|
<<<<<< | :shifted
|
| memory: | shifted/remainder | 0 | 0 | 0 | 0 | 0 | divisor |
| ^
|
| shifted % divisor
[ | | while :remainder
| | |
| | | memory: | shifted | 0 | 0 | 0 | 0 | 0 | divisor | 0 |
| | | ^
| | |
[>>>>>>>+<<<<+<<<-] | | | duplicate :cshifted : copy of shifted
| | |
| | | memory: | 0 | 0 | 0 | shifted | 0 | 0 | divisor | cshifted |
| | | ^
>>>>>> | | | :divisor ^
| | |
[<<+>+>-] | | | duplicate
< | | | |
[>+<-] | | | |
< | | | | :cdiv : copy of divisor
| | |
| | | memory: | 0 | 0 | 0 | shifted | cdiv | 0 | divisor | cshifted |
| | | ^
| | |
| | | subtract :cdiv from :shifted until :shifted is 0
[ | | | | while :cdiv
< | | | | | :shifted
| | | | |
[<<+>+>-] | | | | | duplicate
< | | | | | |
[>+<-] | | | | | |
< | | | | | | :csh
| | | | |
| | | | | memory: | 0 | csh | 0 | shifted/remainder | cdiv | 0 | divisor | cshifted |
| | | | | ^
| | | | |
| | | | | subtract 1 from :shifted if not 0
[ | | | | | | if :csh
>>-<< | | | | | | | subtract 1 from :shifted
[-] | | | | | | | clear
] | | | | | | |
| | | | |
>>> | | | | | :cdiv
- | | | | | subtract 1
] | | | | |
| | |
| | |
| | | memory: | 0 | 0 | 0 | remainder | 0 | 0 | divisor | cshifted |
| | | ^
< | | | :remainder ^
| | |
[>+<<<<+>>>-] | | | duplicate
| | |
| | | memory: | remainder | 0 | 0 | 0 | crem | 0 | divisor | shifted/modulus |
| | | ^
> | | | :crem ^
| | |
| | | clean up modulus if a remainder is left
[ | | | if :crem
>>>[-]<<< | | | | clear :modulus
[-] | | | | clear
] | | | |
| | |
| | | if subtracting :cdiv from :shifted left a remainder we need to do continue subtracting;
| | | otherwise modulus is the modulus between :divisor and :shifted
| | |
<<<< | | | :remainder
] | | |
|
| memory: | 0 | 0 | 0 | 0 | 0 | 0 | divisor | modulus | 0 | cmod | eq26 |
| ^
|
>>>>>>> | :modulus
|
[>>+<+<-] | duplicate
> | |
[<+>-] | |
> | | :cmod : copy of :modulus
|
| memory: | 0 | 0 | 0 | 0 | 0 | 0 | divisor | modulus | 0 | cmod | eq26 |
| ^
|
-------------------------- | subtract 26
|
> | :eq26 : condition equal to 26
+ | add 1 (set true)
|
< | :cmod
[ | if :cmod not equal 26
>-< | | subtract 1 from :eq26 (set false)
[-] | | clear
] | |
|
> | :eq26
|
[ | if :eq26
<<<[-]>>> | | clear :modulus
[-] | | clear
] | |
|
| the modulus operation above gives 26 as a valid modulus; so this is a workaround for setting a
| modulus value of 26 to 0
|
<<<< |
[-] | clear :divisor
|
| memory: | c | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | modulus |
| ^
> | :modulus ^
[<<<<<<<+>>>>>>>-] | move :modulus
|
| memory: | c | 0 | modulus/cc | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| ^
<<<<<<< | :modulus/cc ^
|
| add 97 (ascii for 'a'; making 0 a; 1 b; etc)
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
. | print
[-] | clear
] |
memory: | c | 0 | modulus/cc |
^
<< :c ^
]</lang>
Usage:
Give to the program the key and the word to encrypt, each followed by a space.
Input:
<lang whitespace>10 abc </lang>
Output:
klm
Input: <lang whitespace>16 klm </lang> Output:
abc
C
<lang c>#include <stdio.h>
- include <stdlib.h>
- include <string.h>
- include <ctype.h>
- define caesar(x) rot(13, x)
- define decaesar(x) rot(13, x)
- define decrypt_rot(x, y) rot((26-x), y)
void rot(int c, char *str) { int l = strlen(str);
const char* alpha_low = "abcdefghijklmnopqrstuvwxyz";
const char* alpha_high = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char subst; /* substitution character */
int idx; /* index */
int i; /* loop var */
for (i = 0; i < l; i++) /* for each letter in string */ { if( 0 == isalpha(str[i]) ) continue; /* not alphabet character */
idx = (int) (tolower(str[i]) - 'a') + c) % 26; /* compute index */
if( isupper(str[i]) )
subst = alpha_high[idx];
else
subst = alpha_low[idx];
str[i] = subst;
} }
int main(int argc, char** argv)
{
char str[] = "This is a top secret text message!";
printf("Original: %s\n", str); caesar(str); printf("Encrypted: %s\n", str); decaesar(str); printf("Decrypted: %s\n", str);
return 0; }</lang>
C#
<lang csharp>using System; using System.Linq;
namespace CaesarCypher {
class Program
{
static char Encrypt(char ch, int code)
{
if (!char.IsLetter(ch)) return ch;
char offset = char.IsUpper(ch) ? 'A' : 'a';
return (char)((ch + code - offset) % 26 + offset);
}
static string Encrypt(string input, int code)
{
return new string(input.Select(ch => Encrypt(ch, code)).ToArray());
}
static string Decrypt(string input, int code)
{
return Encrypt(input, 26 - code);
}
const string TestCase = "Pack my box with five dozen liquor jugs.";
static void Main()
{
string str = TestCase;
Console.WriteLine(str);
str = Encrypt(str, 5);
Console.WriteLine("Encrypted: " + str);
str = Decrypt(str, 5);
Console.WriteLine("Decrypted: " + str);
Console.ReadKey();
}
}
}</lang>
- Output:
Pack my box with five dozen liquor jugs. Encrypted: Ufhp rd gtc bnym knaj itejs qnvztw ozlx. Decrypted: Pack my box with five dozen liquor jugs.
C++
<lang Cpp>#include <string>
- include <iostream>
- include <algorithm>
- include <cctype>
class MyTransform { private :
int shift ;
public :
MyTransform( int s ) : shift( s ) { }
char operator( )( char c ) {
if ( isspace( c ) )
return ' ' ;
else {
static std::string letters( "abcdefghijklmnopqrstuvwxyz" ) ; std::string::size_type found = letters.find(tolower( c )) ; int shiftedpos = ( static_cast<int>( found ) + shift ) % 26 ; if ( shiftedpos < 0 ) //in case of decryption possibly shiftedpos = 26 + shiftedpos ; char shifted = letters[shiftedpos] ; return shifted ;
} }
} ;
int main( ) {
std::string input ; std::cout << "Which text is to be encrypted ?\n" ; getline( std::cin , input ) ; std::cout << "shift ?\n" ; int myshift = 0 ; std::cin >> myshift ; std::cout << "Before encryption:\n" << input << std::endl ; std::transform ( input.begin( ) , input.end( ) , input.begin( ) ,
MyTransform( myshift ) ) ;
std::cout << "encrypted:\n" ; std::cout << input << std::endl ; myshift *= -1 ; //decrypting again std::transform ( input.begin( ) , input.end( ) , input.begin( ) ,
MyTransform( myshift ) ) ;
std::cout << "Decrypted again:\n" ; std::cout << input << std::endl ; return 0 ;
}</lang>
- Output:
Which text is to be encrypted ? this is an interesting text shift ? 3 Before encryption: this is an interesting text encrypted: wklv lv dq lqwhuhvwlqj whaw Decrypted again: this is an interesting text
Alternative version - lambda functions, auto, iterators
<lang Cpp>/* caesar cipher */
- include <string>
- include <iostream>
- include <cctype>
int main( ) {
using namespace std;
string input ; int key = 0;
// lambda functions
auto encrypt = [&](char c, int key ) {
char A = ( islower(c) )? 'a': 'A';
c = (isalpha(c))? (c - A + key) % 26 + A : c;
return (char) c;
};
auto decrypt = [&](char c, int key ) {
char A = ( islower(c) )? 'a': 'A';
c = (isalpha(c))? (c - A + (26 - key) ) % 26 + A : c;
return (char) c;
};
cout << "Enter a line of text.\n"; getline( cin , input );
cout << "Enter an integer to shift text.\n";
cin >> key;
while ( (key < 1) || (key > 25) )
{
cout << "must be an integer between 1 and 25 -->" << endl;
cin >> key;
}
cout << "Plain: \t" << input << endl ;
for ( auto & cp : input) // use & for mutability
cp = encrypt(cp, key);
cout << "Encrypted:\t" << input << endl;
for ( auto & cp : input)
cp = decrypt(cp, key);
cout << "Decrypted:\t" << input << endl;
return 0 ;
} </lang>
- Output:
Enter a line of text. This is a line of plain text, 50 characters long. Enter an integer to shift text. 5 Plain: This is a line of plain text, 50 characters long. Encrypted: Ymnx nx f qnsj tk uqfns yj}y1 :5 hmfwfhyjwx qtsl3 Decrypted: This is a line of plain text, 50 characters long.
Clojure
Readable version: <lang Clojure>(defn encrypt-character [offset c]
(if (Character/isLetter c)
(let [v (int c)
base (if (>= v (int \a))
(int \a)
(int \A))
offset (mod offset 26)] ;works with negative offsets too!
(char (+ (mod (+ (- v base) offset) 26)
base)))
c))
(defn encrypt [offset text]
(apply str (map #(encrypt-character offset %) text)))
(defn decrypt [offset text]
(encrypt (- 26 offset) text))
(let [text "The Quick Brown Fox Jumps Over The Lazy Dog."
enc (encrypt -1 text)] (print "Original text:" text "\n") (print "Encryption:" enc "\n") (print "Decryption:" (decrypt -1 enc) "\n"))</lang>
output:
Original text: The Quick Brown Fox Jumps Over The Lazy Dog. Encryption: Sgd Pthbj Aqnvm Enw Itlor Nudq Sgd Kzyx Cnf. Decryption: The Quick Brown Fox Jumps Over The Lazy Dog.
Terser version using replace: <lang Clojure>(defn encode [k s]
(let [f #(take 26 (drop %3 (cycle (range (int %1) (inc (int %2))))))
a #(map char (concat (f \a \z %) (f \A \Z %)))]
(apply str (replace (zipmap (a 0) (a k)) s))))
(defn decode [k s]
(encode (- 26 k) s))</lang>
output:
(encode 12 "The Quick Brown Fox jumped over the lazy dog") => "Ftq Cguow Ndaiz Raj vgybqp ahqd ftq xmlk pas" (decode 12 (encode 12 "The Quick Brown Fox jumped over the lazy dog")) => "The Quick Brown Fox jumped over the lazy dog"
COBOL
COBOL-85 ASCII or EBCIDIC <lang COBOL>
identification division.
program-id. caesar.
data division.
1 msg pic x(50)
value "The quick brown fox jumped over the lazy dog.".
1 offset binary pic 9(4) value 7.
1 from-chars pic x(52).
1 to-chars pic x(52).
1 tabl.
2 pic x(26) value "abcdefghijklmnopqrstuvwxyz".
2 pic x(26) value "ABCDEFGHIJKLMNOPQRSTUVWXYZ".
2 pic x(26) value "abcdefghijklmnopqrstuvwxyz".
2 pic x(26) value "ABCDEFGHIJKLMNOPQRSTUVWXYZ".
procedure division.
begin.
display msg
perform encrypt
display msg
perform decrypt
display msg
stop run
.
encrypt.
move tabl (1:52) to from-chars
move tabl (1 + offset:52) to to-chars
inspect msg converting from-chars
to to-chars
.
decrypt.
move tabl (1 + offset:52) to from-chars
move tabl (1:52) to to-chars
inspect msg converting from-chars
to to-chars
.
end program caesar.
</lang>
- Output:
The quick brown fox jumped over the lazy dog. aol xBpjr iyvDu mvE qBtwlk vCly Aol shGF kvn. The quick brown fox jumped over the lazy dog.
<lang cobol> >>SOURCE FORMAT IS FREE PROGRAM-ID. caesar-cipher.
ENVIRONMENT DIVISION. CONFIGURATION SECTION. REPOSITORY.
FUNCTION encrypt FUNCTION decrypt .
DATA DIVISION. WORKING-STORAGE SECTION. 01 plaintext PIC X(50). 01 offset PIC 99.
01 encrypted-str PIC X(50).
PROCEDURE DIVISION.
DISPLAY "Enter a message to encrypt: " NO ADVANCING ACCEPT plaintext DISPLAY "Enter the amount to shift by: " NO ADVANCING ACCEPT offset
MOVE FUNCTION encrypt(offset, plaintext) TO encrypted-str DISPLAY "Encrypted: " encrypted-str DISPLAY "Decrypted: " FUNCTION decrypt(offset, encrypted-str) .
END PROGRAM caesar-cipher.
FUNCTION-ID. encrypt.
DATA DIVISION. LOCAL-STORAGE SECTION. 01 i PIC 9(3).
01 a PIC 9(3).
LINKAGE SECTION. 01 offset PIC 99. 01 str PIC X(50).
01 encrypted-str PIC X(50).
PROCEDURE DIVISION USING offset, str RETURNING encrypted-str.
MOVE str TO encrypted-str
PERFORM VARYING i FROM 1 BY 1 UNTIL i > FUNCTION LENGTH(str)
IF encrypted-str (i:1) IS NOT ALPHABETIC OR encrypted-str (i:1) = SPACE
EXIT PERFORM CYCLE
END-IF
IF encrypted-str (i:1) IS ALPHABETIC-UPPER
MOVE FUNCTION ORD("A") TO a
ELSE
MOVE FUNCTION ORD("a") TO a
END-IF
MOVE FUNCTION CHAR(FUNCTION MOD(FUNCTION ORD(encrypted-str (i:1))
- a + offset, 26) + a)
TO encrypted-str (i:1)
END-PERFORM
.
END FUNCTION encrypt.
FUNCTION-ID. decrypt.
ENVIRONMENT DIVISION. CONFIGURATION SECTION. REPOSITORY.
FUNCTION encrypt .
DATA DIVISION. LOCAL-STORAGE SECTION. 01 decrypt-offset PIC 99.
LINKAGE SECTION. 01 offset PIC 99. 01 str PIC X(50).
01 decrypted-str PIC X(50).
PROCEDURE DIVISION USING offset, str RETURNING decrypted-str.
SUBTRACT 26 FROM offset GIVING decrypt-offset MOVE FUNCTION encrypt(decrypt-offset, str) TO decrypted-str .
END FUNCTION decrypt.</lang>
- Output:
Enter a message to encrypt: The quick brown fox jumps over the lazy dog. Enter the amount to shift by: 7 Encrypted: Aol xbpjr iyvdu mve qbtwz vcly aol shgf kvn. Decrypted: The quick brown fox jumps over the lazy dog.
CoffeeScript
<lang coffeescript>cipher = (msg, rot) ->
msg.replace /([a-z|A-Z])/g, ($1) ->
c = $1.charCodeAt(0)
String.fromCharCode \
if c >= 97
then (c + rot + 26 - 97) % 26 + 97
else (c + rot + 26 - 65) % 26 + 65
console.log cipher "Hello World", 2 console.log cipher "azAz %^&*()", 3</lang>
- Output:
> coffee foo.coffee Jgnnq Yqtnf dcDc %^&*()
Commodore BASIC
Very generic implementation. Please note that in Commodore BASIC, SHIFT-typed letters (to generate either graphic symbols in upper-case mode, or capital letters in lower-case mode) do not translate to PETSCII characters 97 through 122, but instead to characters 193 through 218.
<lang gwbasic>1 rem caesar cipher 2 rem rosetta code 10 print chr$(147);chr$(14); 15 input "Enter a key value from 1 to 25";kv 20 if kv<1 or kv>25 then print "Out of range.":goto 15 25 gosub 1000 30 print chr$(147);"Enter a message to translate." 35 print:print "Press CTRL-Z when finished.":print 40 mg$="":gosub 2000 45 print chr$(147);"Processing...":gosub 3000 50 print chr$(147);"The translated message is:" 55 print:print cm$ 100 print:print "Do another one? "; 110 get k$:if k$<>"y" and k$<>"n" then 110 120 print k$:if k$="y" then goto 10 130 end
1000 rem generate encoding table 1010 ec$="" 1015 rem lower case 1020 for i=kv to 26:ec$=ec$+chr$(i+64):next i 1021 for i=1 to kv-1:ec$=ec$+chr$(i+64):next i 1025 rem upper case 1030 for i=kv to 26:ec$=ec$+chr$(i+192):next i 1031 for i=1 to kv-1:ec$=ec$+chr$(i+192):next i 1099 return
2000 rem get user input routine 2005 print chr$(18);" ";chr$(146);chr$(157); 2010 get k$:if k$="" then 2010 2012 if k$=chr$(13) then print " ";chr$(157); 2015 print k$; 2020 if k$=chr$(20) then mg$=left$(mg$,len(mg$)-1):goto 2040 2025 if len(mg$)=255 or k$=chr$(26) then return 2030 mg$=mg$+k$ 2040 goto 2005
3000 rem translate message 3005 cm$="" 3010 for i=1 to len(mg$) 3015 c=asc(mid$(mg$,i,1)) 3020 if c<65 or (c>90 and c<193) or c>218 then cm$=cm$+chr$(c):goto 3030 3025 if c>=65 and c<=90 then c=c-64 3030 if c>=193 and c<=218 then c=(c-192)+26 3035 cm$=cm$+mid$(ec$,c,1) 3040 next i 3050 return</lang>
- Output:
Enter a key value from 1 to 25? 10
Enter a message to translate.
Press CTRL-Z when finished.
You know it is going to be a bad day
when the letters in your alphabet soup
spell D-I-S-A-S-T-E-R.
Processing...
The translated message is:
Iye uxyg sd sc qysxq dy lo k lkn nki
grox dro voddobc sx iyeb kvzrklod cyez
czovv N-S-C-K-C-D-O-B.
Do another one? n
ready.
█
Common Lisp
W/ decipher function
<lang lisp>(defun encipher-char (ch key)
(let* ((c (char-code ch)) (la (char-code #\a)) (ua (char-code #\A))
(base (cond ((<= la c (char-code #\z)) la)
((<= ua c (char-code #\Z)) ua)
(nil))))
(if base (code-char (+ (mod (+ (- c base) key) 26) base)) ch)))
(defun caesar-cipher (str key)
(map 'string #'(lambda (c) (encipher-char c key)) str))
(defun caesar-decipher (str key) (caesar-cipher str (- key)))
(let* ((original-text "The five boxing wizards jump quickly")
(key 3)
(cipher-text (caesar-cipher original-text key))
(recovered-text (caesar-decipher cipher-text key)))
(format t " Original: ~a ~%" original-text)
(format t "Encrypted: ~a ~%" cipher-text)
(format t "Decrypted: ~a ~%" recovered-text))</lang>
- Output:
Original: The five boxing wizards jump quickly Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob Decrypted: The five boxing wizards jump quickly
<lang lisp> (defun caesar-encipher (s k)
(map 'string #'(lambda (c) (z c k)) s))
(defun caesar-decipher (s k) (caesar-encipher s (- k)))
(defun z (h k &aux (c (char-code h))
(b (or (when (<= 97 c 122) 97)
(when (<= 65 c 90) 65))))
(if b (code-char (+ (mod (+ (- c b) k) 26) b)) h))
</lang>
- Output:
> (caesar-encipher "The quick brown fox jumps over the lazy dog" 23) "Qeb nrfzh yoltk clu grjmp lsbo qeb ixwv ald" > (caesar-decipher "Qeb nrfzh yoltk clu grjmp lsbo qeb ixwv ald" 23) "The quick brown fox jumps over the lazy dog"
W/o decipher function
1. Note
if rot(text shift) = cyphertext then rot(cyphertext -shift) = text
2. Program
Text manipulation is a source of annoyance. Requiescat in pace.
<lang lisp>(defconstant +rot+ "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz")
(defun rot (text shift)
(map 'string
#'(lambda (x)
(if (find x +rot+)
(char +rot+ (mod (+ (position x +rot+) (* 2 shift)) 52))
x))
text))</lang>
3. Execution
See 1.
- Output:
(rot "Ave Caesar morituri te salutant" 13) Nir Pnrfne zbevghev gr fnyhgnag (rot "Nir Pnrfne zbevghev gr fnyhgnag" -13) Ave Caesar morituri te salutant
Crystal
<lang crystal>class String
ALPHABET = ("A".."Z").to_a
def caesar_cipher(num) self.tr(ALPHABET.join, ALPHABET.rotate(num).join) end
end
- demo
encrypted = "THEQUICKBROWNFOXJUMPSOVERTHELAZYDOG".caesar_cipher(5) decrypted = encrypted.caesar_cipher(-5) </lang>
Cubescript
<lang cubescript>alias modn [ mod (+ (mod $arg1 $arg2) $arg2) $arg2 ] //Cubescript's built-in mod will fail on negative numbers
alias cipher [ push alpha [ "A B C D E F G H I J K L M N O P Q R S T U V W X Y Z" "a b c d e f g h i j k l m n o p q r s t u v w x y z" ] [ push chars [] [ loop i (strlen $arg1) [ looplist n $alpha [ if (! (listlen $chars)) [ alias chars (? (> (listindex $n (substr $arg1 $i 1)) -1) $n []) ] ] alias arg1 ( concatword (substr $arg1 0 $i) ( ? (> (listindex $chars (substr $arg1 $i 1)) -1) ( at $chars ( modn (+ ( listindex $chars (substr $arg1 $i 1) ) $arg2) (listlen $chars) ) ) (substr $arg1 $i 1) ) (substr $arg1 (+ $i 1) (strlen $arg1)) ) alias chars [] ] ] ] result $arg1 ]
alias decipher [ push alpha [ "A B C D E F G H I J K L M N O P Q R S T U V W X Y Z" "a b c d e f g h i j k l m n o p q r s t u v w x y z" ] [ push chars [] [ loop i (strlen $arg1) [ looplist n $alpha [ if (! (listlen $chars)) [ alias chars (? (> (listindex $n (substr $arg1 $i 1)) -1) $n []) ] ] alias arg1 ( concatword (substr $arg1 0 $i) ( ? (> (listindex $chars (substr $arg1 $i 1)) -1) ( at $chars ( modn (- ( listindex $chars (substr $arg1 $i 1) ) $arg2 ) (listlen $chars) ) ) (substr $arg1 $i 1) ) (substr $arg1 (+ $i 1) (strlen $arg1)) ) alias chars [] ] ] ] result $arg1 ]</lang>
Usage: <lang>>>> cipher "The Quick Brown Fox Jumps Over The Lazy Dog." 5 > Ymj Vznhp Gwtbs Ktc Ozrux Tajw Ymj Qfed Itl. >>> decipher "Ymj Vznhp Gwtbs Ktc Ozrux Tajw Ymj Qfed Itl." 5 > The Quick Brown Fox Jumps Over The Lazy Dog.</lang>
D
<lang d>import std.stdio, std.traits;
S rot(S)(in S s, in int key) pure nothrow @safe if (isSomeString!S) {
auto res = s.dup;
foreach (immutable i, ref c; res) {
if ('a' <= c && c <= 'z')
c = ((c - 'a' + key) % 26 + 'a');
else if ('A' <= c && c <= 'Z')
c = ((c - 'A' + key) % 26 + 'A');
}
return res;
}
void main() @safe {
enum key = 3;
immutable txt = "The five boxing wizards jump quickly";
writeln("Original: ", txt);
writeln("Encrypted: ", txt.rot(key));
writeln("Decrypted: ", txt.rot(key).rot(26 - key));
}</lang>
- Output:
Original: The five boxing wizards jump quickly Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob Decrypted: The five boxing wizards jump quickly
Simpler in-place version (same output): <lang d>import std.stdio, std.ascii;
void inplaceRot(char[] txt, in int key) pure nothrow {
foreach (ref c; txt) {
if (isLower(c))
c = (c - 'a' + key) % 26 + 'a';
else if (isUpper(c))
c = (c - 'A' + key) % 26 + 'A';
}
}
void main() {
enum key = 3;
auto txt = "The five boxing wizards jump quickly".dup;
writeln("Original: ", txt);
txt.inplaceRot(key);
writeln("Encrypted: ", txt);
txt.inplaceRot(26 - key);
writeln("Decrypted: ", txt);
}</lang>
A version that uses the standard library (same output): <lang d>import std.stdio, std.ascii, std.string, std.algorithm;
string rot(in string s, in int key) pure nothrow @safe {
auto uppr = uppercase.dup.representation; bringToFront(uppr[0 .. key], uppr[key .. $]); auto lowr = lowercase.dup.representation; bringToFront(lowr[0 .. key], lowr[key .. $]); return s.translate(makeTrans(letters, assumeUTF(uppr ~ lowr)));
}
void main() {
enum key = 3;
immutable txt = "The five boxing wizards jump quickly";
writeln("Original: ", txt);
writeln("Encrypted: ", txt.rot(key));
writeln("Decrypted: ", txt.rot(key).rot(26 - key));
}</lang>
Dart
<lang dart>class Caesar {
int _key;
Caesar(this._key);
int _toCharCode(String s) {
return s.charCodeAt(0);
}
String _fromCharCode(int ch) {
return new String.fromCharCodes([ch]);
}
String _process(String msg, int offset) {
StringBuffer sb=new StringBuffer();
for(int i=0;i<msg.length;i++) {
int ch=msg.charCodeAt(i);
if(ch>=_toCharCode('A')&&ch<=_toCharCode('Z')) {
sb.add(_fromCharCode(_toCharCode("A")+(ch-_toCharCode("A")+offset)%26));
}
else if(ch>=_toCharCode('a')&&ch<=_toCharCode('z')) {
sb.add(_fromCharCode(_toCharCode("a")+(ch-_toCharCode("a")+offset)%26));
} else {
sb.add(msg[i]);
}
}
return sb.toString();
}
String encrypt(String msg) {
return _process(msg, _key);
}
String decrypt(String msg) {
return _process(msg, 26-_key);
}
}
void trip(String msg) {
Caesar cipher=new Caesar(10);
String enc=cipher.encrypt(msg);
String dec=cipher.decrypt(enc);
print("\"$msg\" encrypts to:");
print("\"$enc\" decrypts to:");
print("\"$dec\"");
Expect.equals(msg,dec);
}
main() {
Caesar c2=new Caesar(2);
print(c2.encrypt("HI"));
Caesar c20=new Caesar(20);
print(c20.encrypt("HI"));
// try a few roundtrips
trip("");
trip("A");
trip("z");
trip("Caesar cipher");
trip(".-:/\"\\!");
trip("The Quick Brown Fox Jumps Over The Lazy Dog.");
}</lang>
- Output:
JK BC "" encrypts to: "" decrypts to: "" "A" encrypts to: "K" decrypts to: "A" "z" encrypts to: "j" decrypts to: "z" "Caesar cipher" encrypts to: "Mkockb mszrob" decrypts to: "Caesar cipher" ".-:/"\!" encrypts to: ".-:/"\!" decrypts to: ".-:/"\!" "The Quick Brown Fox Jumps Over The Lazy Dog." encrypts to: "Dro Aesmu Lbygx Pyh Tewzc Yfob Dro Vkji Nyq." decrypts to: "The Quick Brown Fox Jumps Over The Lazy Dog."
Delphi
See #Pascal.
Dyalect
<lang dyalect>func Char.Encrypt(code) {
if !this.IsLetter() {
return this
}
var offset = (this.IsUpper() ? 'A' : 'a').Order()
return Char((this.Order() + code - offset) % 26 + offset)
}
func String.Encrypt(code) {
var xs = []
for c in this {
xs.Add(c.Encrypt(code))
}
return String.Concat(values: xs)
}
func String.Decrypt(code) {
this.Encrypt(26 - code);
}
var str = "Pack my box with five dozen liquor jugs." print(str) str = str.Encrypt(5) print("Encrypted: \(str)") str = str.Decrypt(5) print("Decrypted: \(str)")</lang>
- Output:
Pack my box with five dozen liquor jugs. Encrypted: Ufhp rd gtc bnym knaj itejs qnvztw ozlx. Decrypted: Pack my box with five dozen liquor jugs.
EDSAC order code
The EDSAC had only upper-case letters, which were represented by 5-bit codes. From a programming point of view the assignment of codes to letters was random, so tables are used to convert between EDSAC code and alphabetic position.
In this program, the alphabetic shift to encipher or decipher a message is specified by adding the translation of 'A' to the beginning of the message. For instance, if encipherment shifts letters 3 forward then the message should be prefixed with 'D' to encipher, or 'X' to decipher.
The program prints a test message, enciphered and deciphered, and then prompts for further messages. If the program is running in the EdsacPC simulator, the user can enter a message by storing it in a text file, making that file the active file, and clicking Reset. The message must be terminated by a blank row of tape (represented by '.' in EdsacPC). <lang edsac>
[Caesar cipher for Rosetta Code. EDSAC program, Initial Orders 2.]
[Table for converting alphabetic position 0..25 to EDSAC code.
The EDSAC code is in the high 5 bits.]
T 54 K [access table via C parameter]
P 56 F
T 56 K
AFBFCFDFEFFFGFHFIFJFKFLFMFNFOFPFQFRFSFTFUFVFWFXFYFZF
[Table for converting 5-bit EDSAC code to alphabetic position 0..25.
Computed at run time (so the programmer doesn't need to know the EDSAC codes).
32 entries; entry is -1 if the EDSAC code does not represent a letter.]
T 53 K [access table via B parameter]
P 82 F
[Subroutine to read string from input and
store with char codes in high 5 bits.
String is terminated by blank row of tape, which is stored.
Input: 0F holds address of string in address field (bits 1..11).
22 locations; workspace: 4D]
T 114 K
GKA3FT19@AFA20@T10@I5FA4DR16FT4DA4FUFE14@A21@G18@T5FA10@A2FE4@T5FEFUFK2048F
[Subroutine to print string with character codes in high 5 bits.
String is terminated by blank row of tape, which is not printed.
Input: 0F holds address of string in address field (bits 1..11).
18 locations; orkspace: 4F]
T 136 K
GKA3FT16@AFA2@T5@AFU4FE10@A17@G15@O4FT4FA5@A2FG4@TFEFK2048F
[Define start of user message]
T 47 K [access message via M parameter]
P 350 F [address of message]
T 154 K
G K
[Constants]
[0] P M [address of user message]
[1] A B
[2] A C
[3] T B
[4] P 25 F
[5] P 26 F
[6] P 31 F
[7] K 2048 F [(1) letter shift (2) used in test for
blank row of tape at end of message]
[8] @ F [carriage return]
[9] & F [line feed]
[10] K 4096 F [null char]
[Constant messages. Each includes new line at the end.]
[11] TF EF SF TF IF NF GF @F &F K4096F
[21] P 11 @
[22] EF NF TF EF RF !F MF EF SF SF AF GF EF @F &F K4096F
[38] P 22 @
[39] MF UF SF TF !F SF TF AF RF TF !F WF IF TF HF !F BF !F TF OF !F ZF @F &F K4096F
[64] P 39 @
[Subroutine to convert EDSAC code to alphabetic position.
Input: 4F holds EDSAC code in high 5 bits
Output: 4F holds alphabetic position (0..25, or -1 if not a letter).
Workspace: 5F]
[65] A 3 F [make jump for return]
T 75 @ [plant in code]
A 4 F [load EDSAC code]
R 512 F [shift code into address field]
T 5 F [temp store]
C 5 F [acc := address bits only]
A 1 @ [make order to load alphabetic position]
T 73 @ [plant in code]
[73] A B [load alphabetic position]
T 4 F [store in 4F]
[75] E F [return]
[Subroutine to encipher or decipher a message by Caesar shift.
Input: Message is accessed by the M parameter, and
terminated by a blank row of tape.
Output: 0F = error flag: 0 if OK, < 0 if error (bad message prefix)
Workspace 4F.]
[76] A 3 F [make jump for return]
T 119 @ [plant in code]
A 80 @ [load order to access first char]
T 95 @ [plant in code]
[80] A M [load first char of message]
T 4 F [pass to subroutine]
[82] A 82 @ [get alphabetic position]
G 65 @
A 4 F [load alphabetic position]
U F [to 0F for use as shift]
S 2 F [check it's not 0 or -1]
G 118 @ [error exit if it is]
T 1 F [clear acc]
S F [load negative of shift]
G 108 @ [jump to store first char
and convert rest of message]
[Here after skipping non-letter]
[91] T 4 F [clear acc]
[Here after converting letter]
[92] A 95 @ [load order to read character]
A 2 F [inc address to next character]
T 95 @ [store back]
[95] A M [load char from message (in top 5 bits)]
E 100 @ [if >= 0 then not blank row]
A 7 @ [if < 0, test for blank row]
G 117 @ [jump out if so]
S 7 @ [restore after test]
[100] T 4 F [character to 4F for subroutine]
[101] A 101 @ [for return from subroutine]
G 65 @ [sets 4F := alphabetic position]
A 4 F [to acc]
G 91 @ [if < 0 then not a letter; don't change it]
A F [apply Caesar shift]
[Subtract 26 if required, so result is in range 0..25]
S 5 @ [subtract 26]
E 109 @ [skip next if result >= 0]
[108] A 5 @ [add 26]
[109] A 2 @ [make order to read EDSAC letter at that position]
T 114 @ [plant in code]
A 95 @ [load A order from above]
A 14 C [add 'O F' to make T order]
T 115 @ [plant in code]
[114] A C [load enciphered letter]
[115] T M [overwrite original letter]
E 92 @ [loop back]
[117] T F [flag = 0 for OK]
[118] T F [flag to 0F: 0 if OK, < 0 if error]
[119] E F [return with acc = 0]
[Subroutine to print encipered or deciphered message, plus new line]
[120] A 3 F [make jump order for return]
T 128 @ [plant in code]
A @ [load address of message]
T F [to 0F for print subroutine]
[124] A 124 @
G 136 F [print message, clears acc]
O 8 @ [print new line]
O 9 @
[128] E F [return with acc = 0]
[Main routine]
[129] O 7 @ [set letter shift]
H 6 @ [mult reg has this value throughout;
selects bits 1..5 of 17-bit value]
[Build inverse table from direct table
First initialize all 32 locations to -1]
A 6 @ [work backwards]
[132] A 3 @ [make T order for inverse table]
T 135 @ [plant in code]
S 2 F [make -1 in address field]
[135] T B [store in inverse table]
A 135 @ [get T order]
S 2 F [dec address]
S 3 @ [compare with start of table]
E 132 @ [loop till done]
[Now fill in entries by reversing direct table]
T F [clear acc]
A 4 @ [work backwards]
[142] U 5 F [index in 5F]
A 2 @ [make A order for direct table]
T 145 @ [plant in code]
[145] A C [load entry from direct table, code in top 5 bits]
R 512 F [shift 11 right, 5-bit code to address field]
T 4 F [temp store]
C 4 F [pick out 5-bit code]
A 3 @ [make T order for inverse table]
T 152 @ [plant in code]
A 5 F [load index]
[152] T B [store in inverse table]
A 5 F [load index again]
S 2 F [update index]
E 142 @ [loop back]
[Here when inverse table is complete]
[156] T F [clear acc]
[157] A 21 @ [load address of "testing" message]
T F [to 0F for print subroutine]
[159] A 159 @
G 136 F [print "testing message"]
E 168 @ [jump to read from end of this file]
[Loop back here to get message from user]
[162] A 38 @ [load address of prompt]
T F [to 0F for print subroutine]
[164] A 164 @
G 136 F [print prompt]
O 10 @ [print null to flush teleprinter buffer]
Z F [stop]
[First time here, read message from end of this file.
Later times, read message from file chosen by the user.]
[168] A @ [load address of message]
T F [to 0F for input]
[170] A 170 @
G 114 F [read message]
[172] A 172 @
G 120 @ [print message]
[174] A 174 @
G 76 @ [call Caesar shift subroutine]
A F [load error flag]
E 184 @ [jump if OK]
T F [error, clear acc]
A 64 @ [load address of error message]
T F
[181] A 181 @
G 136 F [print error message]
E 162 @ [back to try again]
[Here if message was enciphered without error]
[184] A 184 @
G 120 @ [print enciphered message]
[186] A 186 @
G 76 @ [call Caesar shift subroutine]
[188] A 188 @
G 120 @ [print deciphered message]
E 162 @ [back for another message]
E 129 Z [define entry point]
P F [acc = 0 on entry]
DGAZA!FREQUENS!LIBYCUM!DUXIT!KARTHAGO!TRIUMPHUM. </lang>
- Output:
TESTING DGAZA FREQUENS LIBYCUM DUXIT KARTHAGO TRIUMPHUM XJDCD IUHTXHQV OLEBFXP GXALW NDUWKDJR WULXPSKXP DGAZA FREQUENS LIBYCUM DUXIT KARTHAGO TRIUMPHUM ENTER MESSAGE WGALLIA EST OMNIS DIVISA IN PARTES TRES ECWHHEW AOP KIJEO ZEREOW EJ LWNPAO PNAO WGALLIA EST OMNIS DIVISA IN PARTES TRES ENTER MESSAGE
Eiffel
<lang eiffel> class APPLICATION
inherit ARGUMENTS
create make
feature {NONE} -- Initialization
make -- Run application. local s: STRING_32 do s := "The tiny tiger totally taunted the tall Till." print ("%NString to encode: " + s) print ("%NEncoded string: " + encode (s, 12)) print ("%NDecoded string (after encoding and decoding): " + decode (encode (s, 12), 12)) end
feature -- Basic operations
decode (to_be_decoded: STRING_32; offset: INTEGER): STRING_32 -- Decode `to be decoded' according to `offset'. do Result := encode (to_be_decoded, 26 - offset) end
encode (to_be_encoded: STRING_32; offset: INTEGER): STRING_32 -- Encode `to be encoded' according to `offset'. local l_offset: INTEGER l_char_code: INTEGER do create Result.make_empty l_offset := (offset \\ 26) + 26 across to_be_encoded as tbe loop if tbe.item.is_alpha then if tbe.item.is_upper then l_char_code := ('A').code + (tbe.item.code - ('A').code + l_offset) \\ 26 Result.append_character (l_char_code.to_character_32) else l_char_code := ('a').code + (tbe.item.code - ('a').code + l_offset) \\ 26 Result.append_character (l_char_code.to_character_32) end else Result.append_character (tbe.item) end end end end </lang>
- Output:
String to encode: The tiny tiger totally taunted the tall Till. Encoded string: Ftq fuzk fusqd fafmxxk fmgzfqp ftq fmxx Fuxx. Decoded string (after encoding and decoding): The tiny tiger totally taunted the tall Till.
Ela
<lang ela>open number char monad io string
chars = "ABCDEFGHIJKLMOPQRSTUVWXYZ"
caesar _ _ [] = "" caesar op key (x::xs) = check shifted ++ caesar op key xs
where orig = indexOf (string.upper $ toString x) chars
shifted = orig `op` key
check val | orig == -1 = x
| val > 24 = trans $ val - 25
| val < 0 = trans $ 25 + val
| else = trans shifted
trans idx = chars:idx
cypher = caesar (+) decypher = caesar (-)
key = 2
do
putStrLn "A string to encode:" str <- readStr putStr "Encoded string: " cstr <- return <| cypher key str put cstr putStrLn "" putStr "Decoded string: " put $ decypher key cstr</lang>
- Output:
A string to encode: HELLO! THIS IS A SECRET MESSAGE! Encoded string: "JGOOQ! VJKU KU C UGETGV PGUUCIG!" Decoded string: "HELLO! THIS IS A SECRET MESSAGE!"
Elena
ELENA 4.x : <lang elena>import system'routines; import system'math; import extensions; import extensions'text;
const string Letters = "abcdefghijklmnopqrstuvwxyz"; const string BigLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; const string TestText = "Pack my box with five dozen liquor jugs."; const int Key = 12;
class Encrypting : Enumerator {
int theKey;
Enumerator theEnumerator;
constructor(int key, string text)
{
theKey := key;
theEnumerator := text.enumerator();
}
bool next() => theEnumerator;
reset() => theEnumerator;
enumerable() => theEnumerator;
get()
{
var ch := theEnumerator.get();
var index := Letters.indexOf(0, ch);
if (-1 < index)
{
^ Letters[(theKey+index).mod:26]
}
else
{
index := BigLetters.indexOf(0, ch);
if (-1 < index)
{
^ BigLetters[(theKey+index).mod:26]
}
else
{
^ ch
}
}
}
}
extension encryptOp {
encrypt(key)
= new Encrypting(key, self).summarize(new StringWriter());
decrypt(key)
= new Encrypting(26 - key, self).summarize(new StringWriter());
}
public program() {
console.printLine("Original text :",TestText);
var encryptedText := TestText.encrypt:Key;
console.printLine("Encrypted text:",encryptedText);
var decryptedText := encryptedText.decrypt:Key;
console.printLine("Decrypted text:",decryptedText);
console.readChar()
}</lang>
- Output:
Original text :Pack my box with five dozen liquor jugs. Encrypted text:Bmow yk naj iuft ruhq palqz xucgad vgse. Decrypted text:Pack my box with five dozen liquor jugs.
Elixir
<lang elixir>defmodule Caesar_cipher do
defp set_map(map, range, key) do
org = Enum.map(range, &List.to_string [&1])
{a, b} = Enum.split(org, key)
Enum.zip(org, b ++ a) |> Enum.into(map)
end
def encode(text, key) do
map = Map.new |> set_map(?a..?z, key) |> set_map(?A..?Z, key)
String.graphemes(text) |> Enum.map_join(fn c -> Map.get(map, c, c) end)
end
end
text = "The five boxing wizards jump quickly" key = 3 IO.puts "Original: #{text}" IO.puts "Encrypted: #{enc = Caesar_cipher.encode(text, key)}" IO.puts "Decrypted: #{Caesar_cipher.encode(enc, -key)}"</lang>
- Output:
Original: The five boxing wizards jump quickly Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob Decrypted: The five boxing wizards jump quickly
Erlang
<lang Erlang> %% Ceasar cypher in Erlang for the rosetta code wiki. %% Implemented by J.W. Luiten
-module(ceasar). -export([main/2]).
%% rot: rotate Char by Key places rot(Char,Key) when (Char >= $A) and (Char =< $Z) or
(Char >= $a) and (Char =< $z) -> Offset = $A + Char band 32, N = Char - Offset, Offset + (N + Key) rem 26;
rot(Char, _Key) ->
Char.
%% key: normalize key. key(Key) when Key < 0 ->
26 + Key rem 26;
key(Key) when Key > 25 ->
Key rem 26;
key(Key) ->
Key.
main(PlainText, Key) ->
Encode = key(Key),
Decode = key(-Key),
io:format("Plaintext ----> ~s~n", [PlainText]),
CypherText = lists:map(fun(Char) -> rot(Char, Encode) end, PlainText),
io:format("Cyphertext ---> ~s~n", [CypherText]),
PlainText = lists:map(fun(Char) -> rot(Char, Decode) end, CypherText).
</lang> Command: <lang Erlang>ceasar:main("The five boxing wizards jump quickly", 3).</lang>
- Output:
Plaintext ----> The five boxing wizards jump quickly Cyphertext ---> Wkh ilyh eralqj zlcdugv mxps txlfnob "The five boxing wizards jump quickly"
ERRE
<lang ERRE> PROGRAM CAESAR
!$INCLUDE="PC.LIB"
PROCEDURE CAESAR(TEXT$,KY%->CY$)
LOCAL I%,C%
FOR I%=1 TO LEN(TEXT$) DO
C%=ASC(MID$(TEXT$,I%))
IF (C% AND $1F)>=1 AND (C% AND $1F)<=26 THEN
C%=(C% AND $E0) OR (((C% AND $1F)+KY%-1) MOD 26+1)
CHANGE(TEXT$,I%,CHR$(C%)->TEXT$)
END IF
END FOR
CY$=TEXT$
END PROCEDURE
BEGIN
RANDOMIZE(TIMER) PLAINTEXT$="Pack my box with five dozen liquor jugs" PRINT(PLAINTEXT$)
KY%=1+INT(25*RND(1)) ! generates random between 1 and 25 CAESAR(PLAINTEXT$,KY%->CYPHERTEXT$) PRINT(CYPHERTEXT$)
CAESAR(CYPHERTEXT$,26-KY%->DECYPHERED$) PRINT(DECYPHERED$)
END PROGRAM </lang>
- Output:
Pack my box with five dozen liquor jugs Qbdl nz cpy xjui gjwf epafo mjrvps kvht Pack my box with five dozen liquor jugs
Euphoria
<lang Euphoria> --caesar cipher for Rosetta Code wiki --User:Lnettnay
--usage eui caesar ->default text, key and encode flag --usage eui caesar 'Text with spaces and punctuation!' 5 D --If text has imbedded spaces must use apostophes instead of quotes so all punctuation works --key = integer from 1 to 25, defaults to 13 --flag = E (Encode) or D (Decode), defaults to E --no error checking is done on key or flag
include std/get.e include std/types.e
sequence cmd = command_line()
sequence val
-- default text for encryption
sequence text = "The Quick Brown Fox Jumps Over The Lazy Dog."
atom key = 13 -- default to Rot-13
sequence flag = "E" -- default to Encrypt
atom offset
atom num_letters = 26 -- number of characters in alphabet
--get text if length(cmd) >= 3 then text = cmd[3] end if
--get key value if length(cmd) >= 4 then val = value(cmd[4]) key = val[2] end if
--get Encrypt/Decrypt flag if length(cmd) = 5 then flag = cmd[5] if compare(flag, "D") = 0 then key = 26 - key end if end if
for i = 1 to length(text) do if t_alpha(text[i]) then if t_lower(text[i]) then offset = 'a' else offset = 'A' end if text[i] = remainder(text[i] - offset + key, num_letters) + offset end if end for
printf(1,"%s\n",{text})
</lang>
- Output:
"The Quick Brown Fox Jumps Over The Lazy Dog." encrypts to: "Gur Dhvpx Oebja Sbk Whzcf Bire Gur Ynml Qbt." decrypts to: "The Quick Brown Fox Jumps Over The Lazy Dog."
F#
<lang fsharp>module caesar =
open System
let private cipher n s =
let shift c =
if Char.IsLetter c then
let a = (if Char.IsLower c then 'a' else 'A') |> int
(int c - a + n) % 26 + a |> char
else c
String.map shift s
let encrypt n = cipher n let decrypt n = cipher (26 - n)</lang>
> caesar.encrypt 2 "HI";; val it : string = "JK" > caesar.encrypt 20 "HI";; val it : string = "BC" > let c = caesar.encrypt 13 "The quick brown fox jumps over the lazy dog.";; val c : string = "Gur dhvpx oebja sbk whzcf bire gur ynml qbt." > caesar.decrypt 13 c;; val it : string = "The quick brown fox jumps over the lazy dog."
Factor
<lang factor>USING: io kernel locals math sequences unicode.categories ; IN: rosetta-code.caesar-cipher
- cipher ( n s -- s' )
[| c |
c Letter? [
c letter? CHAR: a CHAR: A ? :> a
c a - n + 26 mod a +
]
[ c ] if
] :> shift
s [ shift call ] map ;
- encrypt ( n s -- s' ) cipher ;
- decrypt ( n s -- s' ) [ 26 swap - ] dip cipher ;
11 "Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozr." decrypt print 11 "The quick brown fox jumped over the lazy dog." encrypt print</lang>
- Output:
The quick brown fox jumped over the lazy dog. Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozr.
Fantom
Shifts upper/lower case letters, leaves other characters as they are.
<lang fantom> class Main {
static Int shift (Int char, Int key)
{
newChar := char + key
if (char >= 'a' && char <= 'z')
{
if (newChar - 'a' < 0) { newChar += 26 }
if (newChar - 'a' >= 26) { newChar -= 26 }
}
else if (char >= 'A' && char <= 'Z')
{
if (newChar - 'A' < 0) { newChar += 26 }
if (newChar - 'A' >= 26) { newChar -= 26 }
}
else // not alphabetic, so keep as is
{
newChar = char
}
return newChar
}
static Str shiftStr (Str msg, Int key)
{
res := StrBuf()
msg.each { res.addChar (shift(it, key)) }
return res.toStr
}
static Str encode (Str msg, Int key)
{
return shiftStr (msg, key)
}
static Str decode (Str msg, Int key)
{
return shiftStr (msg, -key)
}
static Void main (Str[] args)
{
if (args.size == 2)
{
msg := args[0]
key := Int(args[1])
echo ("$msg with key $key")
echo ("Encode: ${encode(msg, key)}")
echo ("Decode: ${decode(encode(msg, key), key)}")
}
}
} </lang>
Example:
$ fan caesar.fan "Encrypt - With ! Case," 1 Encrypt - With ! Case, with key 1 Encode: Fodszqu - Xjui ! Dbtf, Decode: Encrypt - With ! Case, $ fan caesar.fan "Encrypt - With ! Case," 5 Encrypt - With ! Case, with key 5 Encode: Jshwduy - Bnym ! Hfxj, Decode: Encrypt - With ! Case, $ fan caesar.fan "Encrypt - With ! Case," 10 Encrypt - With ! Case, with key 10 Encode: Oxmbizd - Gsdr ! Mkco, Decode: Encrypt - With ! Case,
Fhidwfe
only encodes letters <lang Fhidwfe> lowers = ['a','z'] uppers = ['A','Z'] function void caesar_encode(message:ptr key:uint) {
len = strlen$ message
for uint [0u,len) with index {
temp = deref_ubyte$ + message index
if in temp lowers {
temp = + temp key// shift lowercase letters
if > temp 'z' {
temp = - temp 26ub
} ;
} {
if in temp uppers {
temp = + temp key// shift uppercase letters
if > temp 'Z' {
temp = - temp 26ub
} ;
} ;//don't shift other characters
}
put_ubyte$ + message index temp
}
} function void caesar_decode(message:ptr key:uint) {
caesar_encode$ message - 26u key
}
key = 1u response = malloc$ 256u puts$ "plaintext: " getline$ response caesar_encode$ response key puts$ "cyphertext: " puts$ response putln$ caesar_decode$ response key puts$ "decoded: " puts$ response free$ response free$ lowers // ranges are objects and must be freed free$ uppers
//this compiles with only 6 warnings! </lang>
Forth
<lang forth>: ceasar ( c n -- c )
over 32 or [char] a - dup 0 26 within if over + 25 > if 26 - then + else 2drop then ;
- ceasar-string ( n str len -- )
over + swap do i c@ over ceasar i c! loop drop ;
- ceasar-inverse ( n -- 'n ) 26 swap - 26 mod ;
2variable test s" The five boxing wizards jump quickly!" test 2!
3 test 2@ ceasar-string test 2@ cr type
3 ceasar-inverse test 2@ ceasar-string test 2@ cr type</lang>
Fortran
<lang fortran>program Caesar_Cipher
implicit none
integer, parameter :: key = 3 character(43) :: message = "The five boxing wizards jump quickly"
write(*, "(2a)") "Original message = ", message call encrypt(message) write(*, "(2a)") "Encrypted message = ", message call decrypt(message) write(*, "(2a)") "Decrypted message = ", message
contains
subroutine encrypt(text)
character(*), intent(inout) :: text
integer :: i
do i = 1, len(text)
select case(text(i:i))
case ('A':'Z')
text(i:i) = achar(modulo(iachar(text(i:i)) - 65 + key, 26) + 65)
case ('a':'z')
text(i:i) = achar(modulo(iachar(text(i:i)) - 97 + key, 26) + 97)
end select
end do
end subroutine
subroutine decrypt(text)
character(*), intent(inout) :: text
integer :: i
do i = 1, len(text)
select case(text(i:i))
case ('A':'Z')
text(i:i) = achar(modulo(iachar(text(i:i)) - 65 - key, 26) + 65)
case ('a':'z')
text(i:i) = achar(modulo(iachar(text(i:i)) - 97 - key, 26) + 97)
end select
end do
end subroutine
end program Caesar_Cipher</lang>
- Output:
Original message = The five boxing wizards jump quickly Encrypted message = Wkh ilyh eralgj zlcdugv mxps txlfnob Decrypted message = The five boxing wizards jump quickly
FreeBASIC
<lang freebasic>' FB 1.05.0 Win64
Sub Encrypt(s As String, key As Integer)
Dim c As Integer
For i As Integer = 0 To Len(s)
Select Case As Const s[i]
Case 65 To 90
c = s[i] + key
If c > 90 Then c -= 26
s[i] = c
Case 97 To 122
c = s[i] + key
If c > 122 Then c -= 26
s[i] = c
End Select
Next
End Sub
Sub Decrypt(s As String, key As Integer)
Dim c As Integer
For i As Integer = 0 To Len(s)
Select Case As Const s[i]
Case 65 To 90
c = s[i] - key
If c < 65 Then c += 26
s[i] = c
Case 97 To 122
c = s[i] - key
If c < 97 Then c += 26
s[i] = c
End Select
Next
End Sub
Dim As String s = "Bright vixens jump; dozy fowl quack." Print "Plain text : "; s Encrypt s, 8 Print "Encrypted : "; s Decrypt s, 8 Print "Decrypted : "; s Sleep</lang>
- Output:
Plain text : Bright vixens jump; dozy fowl quack. Encrypted : Jzqopb dqfmva rcux; lwhg nwet yciks. Decrypted : Bright vixens jump; dozy fowl quack.
Gambas
Click this link to run this code <lang gambas>Public Sub Main() Dim byKey As Byte = 3 'The key (Enter 26 to get the same output as input) Dim byCount As Byte 'Counter Dim sCeasar As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ" 'Used to calculate the cipher Dim sString As String = "The five boxing wizards jump quickly" 'Phrase to encrypt Dim sCoded, sTemp As String 'Various strings
For byCount = 1 To Len(sString) 'Count through each letter in the phrase
If Mid(sString, byCount, 1) = " " Then 'If it's a space.. sCoded &= " " 'Keep it a space Continue 'Jump to the next iteration of the loop Endif sTemp = Mid(sCeasar, InStr(sCeasar, Mid(UCase(sString), byCount, 1)) + byKey, 1) 'Get the new 'coded' letter If Asc(Mid(sString, byCount, 1)) > 96 Then sTemp = Chr(Asc(sTemp) + 32) 'If the original was lower case then make the new 'coded' letter lower case sCoded &= sTemp 'Add the result to the code string
Next
Print sString & gb.NewLine & sCoded 'Print the result
End</lang> Output:
The five boxing wizards jump quickly Wkh ilyh eralqj zlcdugv mxps txlfnob
GAP
<lang gap>CaesarCipher := function(s, n) local r, c, i, lower, upper; lower := "abcdefghijklmnopqrstuvwxyz"; upper := "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; r := ""; for c in s do i := Position(lower, c); if i <> fail then Add(r, lower[RemInt(i + n - 1, 26) + 1]); else i := Position(upper, c); if i <> fail then Add(r, upper[RemInt(i + n - 1, 26) + 1]); else Add(r, c); fi; fi; od; return r; end;
CaesarCipher("IBM", 25);
- "HAL"
CaesarCipher("Vgg cphvi wzdibn vmz wjmi amzz viy zlpvg di ydbidot viy mdbcon.", 5);
- "All human beings are born free and equal in dignity and rights."</lang>
GFA Basic
<lang basic> ' ' Caesar cypher ' OPENW 1 ! Creates a window for handling input/output CLEARW 1 INPUT "string to encrypt ";text$ INPUT "encryption key ";key% encrypted$=@encrypt$(UPPER$(text$),key%) PRINT "Encrypted: ";encrypted$ PRINT "Decrypted: ";@decrypt$(encrypted$,key%) ' PRINT "(Press any key to end program.)" ~INP(2) CLOSEW 1 ' FUNCTION encrypt$(text$,key%)
LOCAL result$,i%,c%
result$=""
FOR i%=1 TO LEN(text$)
c%=ASC(MID$(text$,i%))
IF c%<ASC("A") OR c%>ASC("Z") ! don't encrypt non A-Z
result$=result$+CHR$(c%)
ELSE
c%=c%+key%
IF c%>ASC("Z")
c%=c%-26
ENDIF
result$=result$+CHR$(c%)
ENDIF
NEXT i%
RETURN result$
ENDFUNC ' FUNCTION decrypt$(text$,key%)
RETURN @encrypt$(text$,26-key%)
ENDFUNC </lang>
Go
Obvious solution with explicit testing for character ranges: <lang go>package main
import (
"fmt" "strings"
)
type ckey struct {
enc, dec func(rune) rune
}
func newCaesar(k int) (*ckey, bool) {
if k < 1 || k > 25 {
return nil, false
}
rk := rune(k)
return &ckey{
enc: func(c rune) rune {
if c >= 'a' && c <= 'z'-rk || c >= 'A' && c <= 'Z'-rk {
return c + rk
} else if c > 'z'-rk && c <= 'z' || c > 'Z'-rk && c <= 'Z' {
return c + rk - 26
}
return c
},
dec: func(c rune) rune {
if c >= 'a'+rk && c <= 'z' || c >= 'A'+rk && c <= 'Z' {
return c - rk
} else if c >= 'a' && c < 'a'+rk || c >= 'A' && c < 'A'+rk {
return c - rk + 26
}
return c
},
}, true
}
func (ck ckey) encipher(pt string) string {
return strings.Map(ck.enc, pt)
}
func (ck ckey) decipher(ct string) string {
return strings.Map(ck.dec, ct)
}
func main() {
pt := "The five boxing wizards jump quickly"
fmt.Println("Plaintext:", pt)
for _, key := range []int{0, 1, 7, 25, 26} {
ck, ok := newCaesar(key)
if !ok {
fmt.Println("Key", key, "invalid")
continue
}
ct := ck.encipher(pt)
fmt.Println("Key", key)
fmt.Println(" Enciphered:", ct)
fmt.Println(" Deciphered:", ck.decipher(ct))
}
}</lang> Data driven version using functions designed for case conversion. (And for method using % operator, see Vigenère_cipher#Go.) <lang go>package main
import (
"fmt" "strings" "unicode"
)
type ckey struct {
enc, dec unicode.SpecialCase
}
func newCaesar(k int) (*ckey, bool) {
if k < 1 || k > 25 {
return nil, false
}
i := uint32(k)
r := rune(k)
return &ckey{
unicode.SpecialCase{
{'A', 'Z' - i, [3]rune{r}},
{'Z' - i + 1, 'Z', [3]rune{r - 26}},
{'a', 'z' - i, [3]rune{r}},
{'z' - i + 1, 'z', [3]rune{r - 26}},
},
unicode.SpecialCase{
{'A', 'A' + i - 1, [3]rune{26 - r}},
{'A' + i, 'Z', [3]rune{-r}},
{'a', 'a' + i - 1, [3]rune{26 - r}},
{'a' + i, 'z', [3]rune{-r}},
},
}, true
}
func (ck ckey) encipher(pt string) string {
return strings.ToUpperSpecial(ck.enc, pt)
}
func (ck ckey) decipher(ct string) string {
return strings.ToUpperSpecial(ck.dec, ct)
}
func main() {
pt := "The five boxing wizards jump quickly"
fmt.Println("Plaintext:", pt)
for _, key := range []int{0, 1, 7, 25, 26} {
ck, ok := newCaesar(key)
if !ok {
fmt.Println("Key", key, "invalid")
continue
}
ct := ck.encipher(pt)
fmt.Println("Key", key)
fmt.Println(" Enciphered:", ct)
fmt.Println(" Deciphered:", ck.decipher(ct))
}
}</lang>
- Output:
(either version)
Plaintext: The five boxing wizards jump quickly Key 0 invalid Key 1 Enciphered: Uif gjwf cpyjoh xjabset kvnq rvjdlmz Deciphered: The five boxing wizards jump quickly Key 7 Enciphered: Aol mpcl ivepun dpghykz qbtw xbpjrsf Deciphered: The five boxing wizards jump quickly Key 25 Enciphered: Sgd ehud anwhmf vhyzqcr itlo pthbjkx Deciphered: The five boxing wizards jump quickly Key 26 invalid
Groovy
Java style: <lang groovy>def caesarEncode(cipherKey, text) {
def builder = new StringBuilder()
text.each { character ->
int ch = character[0] as char
switch(ch) {
case 'a'..'z': ch = ((ch - 97 + cipherKey) % 26 + 97); break
case 'A'..'Z': ch = ((ch - 65 + cipherKey) % 26 + 65); break
}
builder << (ch as char)
}
builder as String
} def caesarDecode(cipherKey, text) { caesarEncode(26 - cipherKey, text) }</lang>
Functional style: <lang groovy>def caesarEncode(cipherKey, text) {
text.chars.collect { c ->
int off = c.isUpperCase() ? 'A' : 'a'
c.isLetter() ? (((c as int) - off + cipherKey) % 26 + off) as char : c
}.join()
} def caesarDecode(cipherKey, text) { caesarEncode(26 - cipherKey, text) }</lang>
Ninja style: <lang groovy>def caesarEncode(k, text) {
(text as int[]).collect { it==' ' ? ' ' : (((it & 0x1f) + k - 1) % 26 + 1 | it & 0xe0) as char }.join()
} def caesarDecode(k, text) { caesarEncode(26 - k, text) }</lang>
Using built in 'tr' function and a replacement alphabet: <lang groovy>def caesarEncode(k, text) {
text.tr('a-zA-Z', ((('a'..'z')*2)[k..(k+25)] + (('A'..'Z')*2)[k..(k+25)]).join())
} def caesarDecode(cipherKey, text) { caesarEncode(26 - cipherKey, text) }</lang> and the same with closures for somewhat better readability: <lang groovy>def caesarEncode(k, text) {
def c = { (it*2)[k..(k+25)].join() }
text.tr('a-zA-Z', c('a'..'z') + c('A'..'Z'))
} def caesarDecode(cipherKey, text) { caesarEncode(26 - cipherKey, text) }</lang> Test code: <lang groovy> def plainText = "The Quick Brown Fox jumped over the lazy dog" def cipherKey = 12 def cipherText = caesarEncode(cipherKey, plainText) def decodedText = caesarDecode(cipherKey, cipherText)
println "plainText: $plainText" println "cypherText($cipherKey): $cipherText" println "decodedText($cipherKey): $decodedText"
assert plainText == decodedText </lang>
- Output:
plainText: The Quick Brown Fox jumped over the lazy dog cypherText(12): Ftq Cguow Ndaiz Raj vgybqp ahqd ftq xmlk pas decodedText(12): The Quick Brown Fox jumped over the lazy dog
Haskell
<lang haskell>module Caesar (caesar, uncaesar) where
import Data.Char
caesar, uncaesar :: (Integral a) => a -> String -> String caesar k = map f
where f c = case generalCategory c of
LowercaseLetter -> addChar 'a' k c
UppercaseLetter -> addChar 'A' k c
_ -> c
uncaesar k = caesar (-k)
addChar :: (Integral a) => Char -> a -> Char -> Char addChar b o c = chr $ fromIntegral (b' + (c' - b' + o) `mod` 26)
where b' = fromIntegral $ ord b
c' = fromIntegral $ ord c
</lang>
And trying it out in GHCi:
*Main> caesar 1 "hal" "ibm" *Main> unCaesar 1 "ibm" "hal"
Similarly, but allowing for negative cipher keys, and using isAlpha, isUpper, negate:
<lang haskell>import Data.Bool (bool) import Data.Char (chr, isAlpha, isUpper, ord)
CAESAR CIPHER ---------------------
caesar, uncaesar :: Int -> String -> String caesar = fmap . tr uncaesar = caesar . negate
tr :: Int -> Char -> Char tr offset c
| isAlpha c =
chr
. ((+) <*> (flip mod 26 . (-) (offset + ord c)))
$ bool 97 65 (isUpper c)
| otherwise = c
TEST -------------------------
main :: IO () main = do
let k = -114
cipher = caesar k
plain = "Curio, Cesare venne, e vide e vinse ? "
mapM_ putStrLn $ [cipher, uncaesar k . cipher] <*> [plain]</lang>
- Output:
Skhye, Suiqhu luddu, u lytu u lydiu ? Curio, Cesare venne, e vide e vinse ?
Or with proper error handling: <lang haskell>{-# LANGUAGE LambdaCase #-} module Main where
import Control.Error (tryRead, tryAt) import Control.Monad.Trans (liftIO) import Control.Monad.Trans.Except (ExceptT, runExceptT)
import Data.Char import System.Exit (die) import System.Environment (getArgs)
main :: IO () main = runExceptT parseKey >>= \case
Left err -> die err
Right k -> interact $ caesar k
parseKey :: (Read a, Integral a) => ExceptT String IO a parseKey = liftIO getArgs >>=
flip (tryAt "Not enough arguments") 0 >>=
tryRead "Key is not a valid integer"
caesar :: (Integral a) => a -> String -> String caesar k = map f
where f c = case generalCategory c of
LowercaseLetter -> addChar 'a' k c
UppercaseLetter -> addChar 'A' k c
_ -> c
addChar :: (Integral a) => Char -> a -> Char -> Char addChar b o c = chr $ fromIntegral (b' + (c' - b' + o) `mod` 26)
where b' = fromIntegral $ ord b
c' = fromIntegral $ ord c</lang>
Hoon
<lang Hoon>|%
++ enc |= [msg=tape key=@ud] ^- tape (turn `(list @)`msg |=(n=@ud (add (mod (add (sub n 'A') key) 26) 'A'))) ++ dec |= [msg=tape key=@ud] (enc msg (sub 26 key)) --</lang>
Icon and Unicon
Strictly speaking a Ceasar Cipher is a shift of 3 (the default in this case). <lang Icon>procedure main() ctext := caesar(ptext := map("The quick brown fox jumped over the lazy dog")) dtext := caesar(ctext,,"decrypt") write("Plain text = ",image(ptext)) write("Encphered text = ",image(ctext)) write("Decphered text = ",image(dtext)) end
procedure caesar(text,k,mode) #: mono-alphabetic shift cipher /k := 3 k := (((k % *&lcase) + *&lcase) % *&lcase) + 1 case mode of {
&null|"e"|"encrypt": return map(text,&lcase,(&lcase||&lcase)[k+:*&lcase]) "d"|"decrypt" : return map(text,(&lcase||&lcase)[k+:*&lcase],&lcase) }
end</lang>
- Output:
Plain text = "the quick brown fox jumped over the lazy dog" Encphered text = "wkh txlfn eurzq ira mxpshg ryhu wkh odcb grj" Decphered text = "the quick brown fox jumped over the lazy dog"
IS-BASIC
<lang IS-BASIC>100 PROGRAM "CaesarCi.bas" 110 STRING M$*254 120 INPUT PROMPT "String: ":M$ 130 DO 140 INPUT PROMPT "Key (1-25): ":KEY 150 LOOP UNTIL KEY>0 AND KEY<26 160 PRINT "Original message: ";M$ 170 CALL ENCRYPT(M$,KEY) 180 PRINT "Encrypted message: ";M$ 190 CALL DECRYPT(M$,KEY) 200 PRINT "Decrypted message: ";M$ 210 DEF ENCRYPT(REF M$,KEY) 220 STRING T$*254 230 LET T$="" 240 FOR I=1 TO LEN(M$) 250 SELECT CASE M$(I) 260 CASE "A" TO "Z" 270 LET T$=T$&CHR$(65+MOD(ORD(M$(I))-65+KEY,26)) 280 CASE "a" TO "z" 290 LET T$=T$&CHR$(97+MOD(ORD(M$(I))-97+KEY,26)) 300 CASE ELSE 310 LET T$=T$&M$(I) 320 END SELECT 330 NEXT 340 LET M$=T$ 350 END DEF 360 DEF DECRYPT(REF M$,KEY) 370 STRING T$*254 380 LET T$="" 390 FOR I=1 TO LEN(M$) 400 SELECT CASE M$(I) 410 CASE "A" TO "Z" 420 LET T$=T$&CHR$(65+MOD(ORD(M$(I))-39-KEY,26)) 430 CASE "a" TO "z" 440 LET T$=T$&CHR$(97+MOD(ORD(M$(I))-71-KEY,26)) 450 CASE ELSE 460 LET T$=T$&M$(I) 470 END SELECT 480 NEXT 490 LET M$=T$ 500 END DEF</lang>
J
If we assume that the task also requires us to leave non-alphabetic characters alone: <lang j>cndx=: [: , 65 97 +/ 26 | (i.26)&+ caesar=: (cndx 0)}&a.@u:@cndx@[ {~ a.i.]</lang> Example use:<lang j> 2 caesar 'This simple "monoalphabetic substitution cipher" provides almost no security, ...' Vjku ukorng "oqpqcnrjcdgvke uwduvkvwvkqp ekrjgt" rtqxkfgu cnoquv pq ugewtkva, ...</lang> If we instead assume the task only requires we treat upper case characters: <lang j>CAESAR=:1 :'(26|m&+)&.((26{.64}.a.)&i.)'</lang> Example use:<lang j> 20 CAESAR 'HI' BC</lang>
Janet
<lang janet> (def alphabet "abcdefghijklmnopqrstuvwxyz")
(defn rotate
"shift bytes given x"
[str x]
(let [r (% x (length alphabet))
b (string/bytes str)
abyte (get (string/bytes "a") 0)
zbyte (get (string/bytes "z") 0)]
(var result @[])
(for i 0 (length b)
(let [ch (bor (get b i) 0x20)] # convert uppercase to lowercase
(when (and (<= abyte ch) (<= ch zbyte))
(array/push result (get alphabet (% (+ (+ (+ (- zbyte abyte) 1) (- ch abyte)) r) (length alphabet)))))))
(string/from-bytes ;result)))
(defn code
"encodes and decodes str given argument type" [str rot type] (case type :encode (rotate str rot) :decode (rotate str (* rot -1))))
(defn main [& args]
(let [cipher (code "The quick brown fox jumps over the lazy dog" 23 :encode)
str (code cipher 23 :decode)]
(print cipher)
(print str)))
</lang>
- Output:
> encode: "qebnrfzhyoltkclugrjmplsboqebixwvald" > decode: "thequickbrownfoxjumpsoverthelazydog"
Java
<lang java5>public class Cipher {
public static void main(String[] args) {
String str = "The quick brown fox Jumped over the lazy Dog";
System.out.println( Cipher.encode( str, 12 ));
System.out.println( Cipher.decode( Cipher.encode( str, 12), 12 ));
}
public static String decode(String enc, int offset) {
return encode(enc, 26-offset);
}
public static String encode(String enc, int offset) {
offset = offset % 26 + 26;
StringBuilder encoded = new StringBuilder();
for (char i : enc.toCharArray()) {
if (Character.isLetter(i)) {
if (Character.isUpperCase(i)) {
encoded.append((char) ('A' + (i - 'A' + offset) % 26 ));
} else {
encoded.append((char) ('a' + (i - 'a' + offset) % 26 ));
}
} else {
encoded.append(i);
}
}
return encoded.toString();
}
}</lang>
- Output:
Ftq cguow ndaiz raj Vgybqp ahqd ftq xmlk Pas The quick brown fox Jumped over the lazy Dog
JavaScript
ES5
<lang javascript>function caesar (text, shift) {
return text.toUpperCase().replace(/[^A-Z]/g,).replace(/./g, function(a) {
return String.fromCharCode(65+(a.charCodeAt(0)-65+shift)%26);
});
}
// Tests var text = 'veni, vidi, vici'; for (var i = 0; i<26; i++) {
console.log(i+': '+caesar(text,i));
}</lang>
- Output:
0: VENIVIDIVICI 1: WFOJWJEJWJDJ 2: XGPKXKFKXKEK 3: YHQLYLGLYLFL ...
ES6
<lang javascript>var caesar = (text, shift) => text
.toUpperCase() .replace(/[^A-Z]/g, ) .replace(/./g, a => String.fromCharCode(65 + (a.charCodeAt(0) - 65 + shift) % 26));</lang>
Or, allowing encoding and decoding of both lower and upper case:
<lang JavaScript>((key, strPlain) => {
// Int -> String -> String
let caesar = (k, s) => s.split()
.map(c => tr(
inRange(['a', 'z'], c) ? 'a' :
inRange(['A', 'Z'], c) ? 'A' : 0,
k, c
))
.join();
// Int -> String -> String let unCaesar = (k, s) => caesar(26 - (k % 26), s);
// Char -> Int -> Char -> Char
let tr = (base, offset, char) =>
base ? (
String.fromCharCode(
ord(base) + (
ord(char) - ord(base) + offset
) % 26
)
) : char;
// [a, a] -> a -> b let inRange = ([min, max], v) => !(v < min || v > max);
// Char -> Int let ord = c => c.charCodeAt(0);
// range :: Int -> Int -> [Int]
let range = (m, n) =>
Array.from({
length: Math.floor(n - m) + 1
}, (_, i) => m + i);
// TEST
let strCipher = caesar(key, strPlain),
strDecode = unCaesar(key, strCipher);
return [strCipher, ' -> ', strDecode];
})(114, 'Curio, Cesare venne, e vide e vinse ? ');</lang>
- Output:
Mebsy, Mockbo foxxo, o fsno o fsxco ? , -> , Curio, Cesare venne, e vide e vinse ?
jq
Works with gojq, the Go implementation of jq <lang jq>def encrypt(key):
. as $s
| explode as $xs
| (key % 26) as $offset
| if $offset == 0 then .
else reduce range(0; length) as $i ( {chars: []};
$xs[$i] as $c
| .d = $c
| if ($c >= 65 and $c <= 90) # 'A' to 'Z'
then .d = $c + $offset
| if (.d > 90) then .d += -26 else . end
else if ($c >= 97 and $c <= 122) # 'a' to 'z'
then .d = $c + $offset
| if (.d > 122)
then .d += -26 else . end else . end
end
| .chars[$i] = .d )
| .chars | implode
end ;
def decrypt(key): encrypt(26 - key);
"Bright vixens jump; dozy fowl quack." | .,
(encrypt(8) | ., decrypt(8) )
</lang>
- Output:
Bright vixens jump; dozy fowl quack. Jzqopb dqfmva rcux; lwhg nwet yciks. Bright vixens jump; dozy fowl quack.
Jsish
From Typescript entry. <lang javascript>/* Caesar cipher, in Jsish */ "use strict";
function caesarCipher(input:string, key:number):string {
return input.replace(/([a-z])/g,
function(mat, p1, ofs, str) {
return Util.fromCharCode((p1.charCodeAt(0) + key + 26 - 97) % 26 + 97);
}).replace(/([A-Z])/g,
function(mat, p1, ofs, str) {
return Util.fromCharCode((p1.charCodeAt(0) + key + 26 - 65) % 26 + 65);
});
}
provide('caesarCipher', 1);
if (Interp.conf('unitTest')) {
var str = 'The five boxing wizards jump quickly';
- str;
- 'Enciphered
- ';
- caesarCipher(str, 3);
- 'Enciphered then deciphered';
- caesarCipher(caesarCipher(str, 3), -3);
}
/*
!EXPECTSTART!
str ==> The five boxing wizards jump quickly 'Enciphered:' caesarCipher(str, 3) ==> Wkh ilyh eralqj zlcdugv mxps txlfnob 'Enciphered then deciphered' caesarCipher(caesarCipher(str, 3), -3) ==> The five boxing wizards jump quickly
!EXPECTEND!
- /</lang>
- Output:
prompt$ jsish -u caesarCipher.jsi [PASS] caesarCipher.jsi
Julia
updated version for Julia 1.x | Rename isalpha to isletter #27077 | https://github.com/JuliaLang/julia/pull/27077
<lang julia>
- Caeser cipher
- Julia 1.5.4
- author: manuelcaeiro | https://github.com/manuelcaeiro
function csrcipher(text, key)
ciphtext = ""
for l in text
numl = Int(l)
ciphnuml = numl + key
if numl in 65:90
if ciphnuml > 90
rotciphnuml = ciphnuml - 26
ciphtext = ciphtext * Char(rotciphnuml)
else
ciphtext = ciphtext * Char(ciphnuml)
end
elseif numl in 97:122
if ciphnuml > 122
rotciphnuml = ciphnuml - 26
ciphtext = ciphtext * Char(rotciphnuml)
else
ciphtext = ciphtext * Char(ciphnuml)
end
else
ciphtext = ciphtext * Char(numl)
end
end
return ciphtext
end
text = "Magic Encryption"; key = 13 csrcipher(text, key) </lang>
- Output:
"Zntvp Rapelcgvba"
K
Assumes lowercase letters, and no punctuation.
<lang k>
s:"there is a tide in the affairs of men"
caesar:{ :[" "=x; x; {x!_ci 97+!26}[y]@_ic[x]-97]}'
caesar[s;1]
"uifsf jt b ujef jo uif bggbjst pg nfo" </lang>
Kotlin
<lang scala>// version 1.0.5-2
object Caesar {
fun encrypt(s: String, key: Int): String {
val offset = key % 26
if (offset == 0) return s
var d: Char
val chars = CharArray(s.length)
for ((index, c) in s.withIndex()) {
if (c in 'A'..'Z') {
d = c + offset
if (d > 'Z') d -= 26
}
else if (c in 'a'..'z') {
d = c + offset
if (d > 'z') d -= 26
}
else
d = c
chars[index] = d
}
return chars.joinToString("")
}
fun decrypt(s: String, key: Int): String {
return encrypt(s, 26 - key)
}
}
fun main(args: Array<String>) {
val encoded = Caesar.encrypt("Bright vixens jump; dozy fowl quack.", 8)
println(encoded)
val decoded = Caesar.decrypt(encoded, 8)
println(decoded)
}</lang>
- Output:
Jzqopb dqfmva rcux; lwhg nwet yciks. Bright vixens jump; dozy fowl quack.
LabVIEW
For readability, input is in all caps.
This image is a VI Snippet, an executable image of LabVIEW code. The LabVIEW version is shown on the top-right hand corner. You can download it, then drag-and-drop it onto the LabVIEW block diagram from a file browser, and it will appear as runnable, editable code.
Lambdatalk
The caesar function encodes and decodes texts containing exclusively the set [ABCDEFGHIJKLMNOPQRSTUVWXZ]. <lang scheme> {def caesar
{def caesar.alphabet {A.split ABCDEFGHIJKLMNOPQRSTUVWXYZ}}
{def caesar.delta
{lambda {:s :i :a}
{A.get {% {+ {A.in? {A.get :i :a} {caesar.alphabet}} 26 :s} 26}
{caesar.alphabet}}}}
{def caesar.loop
{lambda {:s :a :b :n :i}
{if {> :i :n}
then :b
else {caesar.r :s
:a
{A.set! :i {caesar.delta :s :i :a} :b}
:n
{+ :i 1}} }}}
{lambda {:shift :txt}
{let { {:s :shift}
{:t {S.replace [^A-Z] by in :txt}} }
{A.join {caesar.loop :s
{A.split :t}
{A.new}
{- {W.length :t} 1}
0 }}}}}
-> caesar
{def text VENI, VIDI, VICI}
-> text
{S.map {lambda {:i} {br}:i: {caesar :i {text}}}
{S.serie 0 26}}
->
0: VENIVIDIVICI 1: WFOJWJEJWJDJ 2: XGPKXKFKXKEK 3: YHQLYLGLYLFL ... 23: SBKFSFAFSFZF 24: TCLGTGBGTGAG 25: UDMHUHCHUHBH 26: VENIVIDIVICI
As a shorter alternative:
{def CAESAR
{def CAESAR.rot
{lambda {:shift :txt :alpha :i}
{A.get {% {+ {A.in? {A.get :i :txt} :alpha} 26 :shift} 26}
:alpha}}}
{def CAESAR.loop
{lambda {:shift :txt :alpha}
{S.map {CAESAR.rot :shift :txt :alpha}
{S.serie 0 {- {A.length :txt} 1}}} }}
{lambda {:shift :txt}
{S.replace \s by in
{CAESAR.loop :shift
{A.split {S.replace \s by in :txt}}
{A.split ABCDEFGHIJKLMNOPQRSTUVWXYZ}} }}}
-> CAESAR
{CAESAR 1 VENI VIDI VICI} -> WFOJWJEJWJDJ {CAESAR 25 WFOJWJEJWJDJ} -> VENIVIDIVICI
</lang>
langur
Using the built-in rotate() function on a number over a range, a number outside of the range will pass through unaltered.
<lang langur>val .rot = f(.s, .key) {
cp2s map(f(.c) rotate(rotate(.c, .key, 'a'..'z'), .key, 'A'..'Z'), s2cp .s)
}
val .s = "A quick brown fox jumped over something." val .key = 3
writeln " original: ", .s writeln "encrypted: ", .rot(.s, .key) writeln "decrypted: ", .rot(.rot(.s, .key), -.key)</lang>
- Output:
original: A quick brown fox jumped over something. encrypted: X nrfzh yoltk clu grjmba lsbo pljbqefkd. decrypted: A quick brown fox jumped over something.
Liberty BASIC
<lang lb>key = 7
Print "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
'Encrypt the text Print CaesarCypher$("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz", key)
'Decrypt the text by changing the key to (26 - key) Print CaesarCypher$(CaesarCypher$("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz", key), (26 - key))
Function CaesarCypher$(string$, key)
If (key < 0) Or (key > 25) Then _
CaesarCypher$ = "Key is Ouside of Bounds" : Exit Function
For i = 1 To Len(string$)
rotate = Asc(Mid$(string$, i, 1))
rotate = (rotate + key)
If Asc(Mid$(string$, i, 1)) > Asc("Z") Then
If rotate > Asc("z") Then rotate = (Asc("a") + (rotate - Asc("z")) - 1)
Else
If rotate > Asc("Z") Then rotate = (Asc("A") + (rotate - Asc("Z")) - 1)
End If
CaesarCypher$ = (CaesarCypher$ + Chr$(rotate))
Next i
End Function</lang>
LiveCode
<lang LiveCode>function caesarCipher rot phrase
local rotPhrase, lowerLetters, upperLetters
put "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz" into lowerLetters
put "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ" into upperLetters
repeat for each char letter in phrase
get charTonum(letter)
if it >= 65 and it <= 90 then
put char ((it + rot) - 64) of upperLetters after rotPhrase
else if it >= 97 and it <= 122 then
put char ((it + rot) - 96) of lowerLetters after rotPhrase
else
put letter after rotPhrase
end if
end repeat
return rotPhrase
end caesarCipher</lang>
Logo
<lang logo>; some useful constants make "lower_a ascii "a make "lower_z ascii "z make "upper_a ascii "A make "upper_z ascii "Z
- encipher a single character
to encipher_char :char :key
local "code make "code ascii :char
local "base make "base 0
ifelse [and (:code >= :lower_a) (:code <= :lower_z)] [make "base :lower_a] [
if [and (:code >= :upper_a) (:code <= :upper_z)] [make "base :upper_a] ]
ifelse [:base > 0] [
output char (:base + (modulo ( :code - :base + :key ) 26 ))
] [
output :char
]
end
- encipher a whole string
to caesar_cipher :string :key
output map [encipher_char ? :key] :string
end
- Demo
make "plaintext "|The five boxing wizards jump quickly| make "key 3 make "ciphertext caesar_cipher :plaintext :key make "recovered caesar_cipher :ciphertext -:key
print sentence "| Original:| :plaintext print sentence "|Encrypted:| :ciphertext print sentence "|Recovered:| :recovered bye</lang>
- Output:
Original: The five boxing wizards jump quickly Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob Recovered: The five boxing wizards jump quickly
Lua
<lang Lua>local function encrypt(text, key) return text:gsub("%a", function(t) local base = (t:lower() == t and string.byte('a') or string.byte('A'))
local r = t:byte() - base r = r + key r = r%26 -- works correctly even if r is negative r = r + base return string.char(r) end) end
local function decrypt(text, key) return encrypt(text, -key) end
caesar = { encrypt = encrypt, decrypt = decrypt, }
-- test do local text = "ABCDEFGHIJKLMNOPQRSTUVWXYZ abcdefghijklmnopqrstuvwxyz" local encrypted = caesar.encrypt(text, 7) local decrypted = caesar.decrypt(encrypted, 7) print("Original text: ", text) print("Encrypted text: ", encrypted) print("Decrypted text: ", decrypted) end </lang>
Fast version
<lang Lua>local memo = {}
local function make_table(k)
local t = {}
local a, A = ('a'):byte(), ('A'):byte()
for i = 0,25 do
local c = a + i
local C = A + i
local rc = a + (i+k) % 26
local RC = A + (i+k) % 26
t[c], t[C] = rc, RC
end
return t
end
local function caesar(str, k, decode)
k = (decode and -k or k) % 26
local t = memo[k]
if not t then
t = make_table(k)
memo[k] = t
end
local res_t = { str:byte(1,-1) }
for i,c in ipairs(res_t) do
res_t[i] = t[c] or c
end
return string.char(unpack(res_t))
end</lang>
M2000 Interpreter
We use a Buffer object (is a pointer type to a block of memory), to store string, to have access using unsigned integers.
<lang M2000 Interpreter> a$="THIS IS MY TEXT TO ENCODE WITH CAESAR CIPHER" Function Cipher$(a$, N) {
If Len(a$)=0 Then Exit
a$=Ucase$(a$)
N=N mod 25 +1
\\ Integer in Mem is unsigned number
Buffer Mem as Integer*Len(a$)
Return Mem, 0:=a$
For i=0 to Len(a$)-1 {
If Eval(mem, i)>=65 and Eval(mem, i)<=90 then Return Mem, i:=(Eval(mem, i)-65+N) mod 26+65
}
=Eval$(Mem)
} B$=Cipher$(a$, 12) Print B$ Print Cipher$(B$,12)
</lang>
Maple
<lang Maple> > StringTools:-Encode( "The five boxing wizards jump quickly", encoding = alpharot[3] );
"Wkh ilyh eralqj zlcdugv mxps txlfnob"
> StringTools:-Encode( %, encoding = alpharot[ 23 ] );
"The five boxing wizards jump quickly"
</lang> (The symbol % refers the the last (non-NULL) value computed.)
Mathematica / Wolfram Language
<lang Mathematica>cypher[mesg_String,n_Integer]:=StringReplace[mesg,Flatten[Thread[Rule[#,RotateLeft[#,n]]]&/@CharacterRange@@@{{"a","z"},{"A","Z"}}]]</lang>
- Output:
cypher["The five boxing wizards jump quickly",3] -> Wkh ilyh eralqj zlcdugv mxps txlfnob
MATLAB / Octave
<lang Matlab> function s = cipherCaesar(s, key)
s = char( mod(s - 'A' + key, 25 ) + 'A');
end;
function s = decipherCaesar(s, key)
s = char( mod(s - 'A' - key, 25 ) + 'A');
end; </lang>
Here is a test: <lang Matlab> decipherCaesar(cipherCaesar('ABC',4),4)
ans = ABC </lang>
Microsoft Small Basic
<lang Microsoft Small Basic> TextWindow.Write("Enter a 1-25 number key (-ve number to decode): ") key = TextWindow.ReadNumber() TextWindow.Write("Enter message: ") message = text.ConvertToUpperCase(TextWindow.Read()) caeser = "" For n = 1 To Text.GetLength(message)
letter = Text.GetSubText(message,n,1)
code = Text.GetCharacterCode(letter)
If code = 32 Then
newCode = 32
Else
newCode = code + key
If newCode > 90 Then
newCode = newCode - 26
ElseIf newCode < 65 then
newCode = newCode + 26
EndIf
EndIf
codeLetter = Text.GetCharacter(newCode)
caeser = Text.Append(caeser,codeLetter)
EndFor TextWindow.WriteLine(message) TextWindow.WriteLine(caeser) </lang>
- Output:
Enter a 1-25 number key (-ve number to decode): 10 Enter message: HAVE A NICE DAY HAVE A NICE DAY RKFO K XSMO NKI Press any key to continue... Enter a 1-25 number key (-ve number to decode): -10 Enter message: RKFO K XSMO NKI RKFO K XSMO NKI HAVE A NICE DAY Press any key to continue...
MiniScript
<lang MiniScript>caesar = function(s, key)
chars = s.values
for i in chars.indexes
c = chars[i]
if c >= "a" and c <= "z" then chars[i] = char(97 + (code(c)-97+key)%26)
if c >= "A" and c <= "Z" then chars[i] = char(65 + (code(c)-65+key)%26)
end for
return chars.join("")
end function
print caesar("Hello world!", 7) print caesar("Olssv dvysk!", 26-7)</lang>
- Output:
Olssv dvysk! Hello world!
ML
mLite
In this implementation, the offset can be positive or negative and is wrapped around if greater than 25 or less than -25. <lang ocaml>fun readfile () = readfile []
| x = let val ln = readln ()
in if eof ln then
rev x
else
readfile ` ln :: x
end
local val lower_a = ord #"a"; val lower_z = ord #"z"; val upper_a = ord #"A"; val upper_z = ord #"Z";
fun which (c_upper c) = (upper_a, upper_z) | _ = (lower_a, lower_z) ;
fun scale (c, az) where (c > #1 az) = scale( (#0 az + (c - #1 az - 1)), az) | (c, az) = c
in fun encipher ([], offset, t) = implode ` rev t | (x :: xs, offset, t) where (c_alphabetic x) = encipher (xs, offset, (chr ` scale (ord x + offset, which x)) :: t) | (x :: xs, offset, t) = encipher (xs, offset, x :: t) | (s, offset) = if (offset < 0) then encipher (explode s, 26 + (offset rem 26), []) else encipher (explode s, offset rem 26, []) end
fun default (false, y) = y | (x, _) = x
map println ` map (fn s = encipher (s,ston ` default (argv 0, "1"))) ` readfile (); </lang> The string for encoding is supplied as an input stream, and the offset supplied on the command line (defaults to 1). For example
echo The cat sat on the mat | mlite -f caecip.m ~5
Output:
Ocz xvo nvo ji ocz hvo
Modula-2
<lang modula2>MODULE CaesarCipher; FROM Conversions IMPORT IntToStr; FROM Terminal IMPORT WriteString, WriteLn, ReadChar;
TYPE String = ARRAY[0..64] OF CHAR;
PROCEDURE Encrypt(p : String; key : CARDINAL) : String; VAR e : String; VAR i,t : CARDINAL; VAR c : CHAR; BEGIN
FOR i:=0 TO HIGH(p) DO
IF p[i]=0C THEN BREAK; END;
t := ORD(p[i]);
IF (p[i]>='A') AND (p[i]<='Z') THEN
t := t + key;
IF t>ORD('Z') THEN
t := t - 26;
END;
ELSIF (p[i]>='a') AND (p[i]<='z') THEN
t := t + key;
IF t>ORD('z') THEN
t := t - 26;
END;
END;
e[i] := CHR(t);
END;
RETURN e;
END Encrypt;
PROCEDURE Decrypt(p : String; key : CARDINAL) : String; VAR e : String; VAR i,t : CARDINAL; VAR c : CHAR; BEGIN
FOR i:=0 TO HIGH(p) DO
IF p[i]=0C THEN BREAK; END;
t := ORD(p[i]);
IF (p[i]>='A') AND (p[i]<='Z') THEN
t := t - key;
IF t<ORD('A') THEN
t := t + 26;
END;
ELSIF (p[i]>='a') AND (p[i]<='z') THEN
t := t - key;
IF t<ORD('a') THEN
t := t + 26;
END;
END;
e[i] := CHR(t);
END;
RETURN e;
END Decrypt;
VAR txt,enc : String; VAR key : CARDINAL; BEGIN
txt := "The five boxing wizards jump quickly"; key := 3;
WriteString("Original: ");
WriteString(txt);
WriteLn;
enc := Encrypt(txt, key);
WriteString("Encrypted: ");
WriteString(enc);
WriteLn;
WriteString("Decrypted: ");
WriteString(Decrypt(enc, key));
WriteLn;
ReadChar;
END CaesarCipher.</lang>
Modula-3
This implementation distinguishes between "encoding" and "encryption." The former turns letters into numbers; the latter turns numbers into different ("cryptic") numbers. The distinction between "decoding" and "decryption" is similar. It also illustrates the use of exceptions in Modula-3.
<lang modula3>MODULE Caesar EXPORTS Main;
IMPORT IO, IntSeq, Text;
EXCEPTION BadCharacter; (* Used whenever message contains a non-alphabetic character. *)
PROCEDURE Encode(READONLY message: TEXT; numbers: IntSeq.T) RAISES { BadCharacter } = (* Converts upper or lower case letter to 0..25. Raises a "BadCharacter" exception for non-alphabetic characters.
- )
VAR
c: CHAR; v: INTEGER;
BEGIN
FOR i := 0 TO Text.Length(message) - 1 DO
c := Text.GetChar(message, i);
CASE c OF
| 'A'..'Z' => v := ORD(c) - ORD('A');
| 'a'..'z' => v := ORD(c) - ORD('a');
ELSE
RAISE BadCharacter;
END;
numbers.addhi(v);
END;
END Encode;
PROCEDURE Decode(READONLY numbers: IntSeq.T; VAR message: TEXT) = (* converts numbers in 0..26 to lower case characters *) BEGIN
FOR i := 0 TO numbers.size() - 1 DO
message := message & Text.FromChar(VAL(numbers.get(i) + ORD('a'), CHAR));
END;
END Decode;
PROCEDURE Crypt(numbers: IntSeq.T; key: INTEGER) = (* In the Caesar cipher, encryption and decryption are really the same; one adds the key, the other subtracts it. We can view this as adding a positive or nevative integer; the common task is adding an integer. We call this "Crypt".
- )
BEGIN
FOR i := 0 TO numbers.size() - 1 DO numbers.put(i, (numbers.get(i) + key) MOD 26); END;
END Crypt;
PROCEDURE Encrypt(numbers: IntSeq.T; key := 4) = (* Encrypts a message of numbers using the designated key. The result is also stored in "numbers".
- )
BEGIN
Crypt(numbers, key);
END Encrypt;
PROCEDURE Decrypt(numbers: IntSeq.T; key := 4) = (* Decrypts a message of numbers using the designated key. The result is also stored in "numbers".
- )
BEGIN
Crypt(numbers, -key);
END Decrypt;
VAR
message := ""; buffer := NEW(IntSeq.T).init(22); (* sequence of 22 int's *)
BEGIN
TRY
Encode("WhenCaesarSetOffToGaul", buffer);
EXCEPT BadCharacter =>
(*
This should never occur.
Try adding spaces to the above to see what happens.
*)
IO.Put("Encountered a bad character in the input; completing partial task\n");
END;
Encrypt(buffer);
Decrypt(buffer);
Decode(buffer, message);
IO.Put(message); IO.PutChar('\n');
END Caesar.</lang>
- Output:
Notice the output comes out all lower-case.
whencaesarsetofftogaul
Nanoquery
<lang Nanoquery>def caesar_encode(plaintext, shift) uppercase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" lowercase = "abcdefghijklmnopqrstuvwxyz"
cipher = "" for char in plaintext if char in uppercase cipher += uppercase[uppercase[char] - (26 - shift)] else if char in lowercase cipher += lowercase[lowercase[char] - (26 - shift)] else cipher += char end end
return cipher end
def caesar_decode(cipher, shift) uppercase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" lowercase = "abcdefghijklmnopqrstuvwxyz"
plaintext = "" for char in cipher if char in uppercase plaintext += uppercase[uppercase[char] - shift] else if char in lowercase plaintext += lowercase[lowercase[char] - shift] else plaintext += char end end
return plaintext end</lang>
NetRexx
The cipher code in this sample is also used in the Rot-13 – NetRexx task. <lang NetRexx>/* NetRexx */
options replace format comments java crossref savelog symbols nobinary
messages = [ -
'The five boxing wizards jump quickly', - 'Attack at dawn!', - 'HI']
keys = [1, 2, 20, 25, 13]
loop m_ = 0 to messages.length - 1
in = messages[m_] loop k_ = 0 to keys.length - 1 say 'Caesar cipher, key:' keys[k_].right(3) ec = caesar_encipher(in, keys[k_]) dc = caesar_decipher(ec, keys[k_]) say in say ec say dc say end k_ say 'Rot-13:' ec = rot13(in) dc = rot13(ec) say in say ec say dc say end m_
return
method rot13(input) public static signals IllegalArgumentException
return caesar(input, 13, isFalse)
method caesar(input = Rexx, idx = int, caps = boolean) public static signals IllegalArgumentException
if idx < 1 | idx > 25 then signal IllegalArgumentException()
-- 12345678901234567890123456 itab = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' shift = itab.length - idx parse itab tl +(shift) tr otab = tr || tl
if caps then input = input.upper
cipher = input.translate(itab || itab.lower, otab || otab.lower)
return cipher
method caesar_encipher(input = Rexx, idx = int, caps = boolean) public static signals IllegalArgumentException
return caesar(input, idx, caps)
method caesar_decipher(input = Rexx, idx = int, caps = boolean) public static signals IllegalArgumentException
return caesar(input, int(26) - idx, isFalse)
method caesar_encipher(input = Rexx, idx = int) public static signals IllegalArgumentException
return caesar(input, idx, isFalse)
method caesar_decipher(input = Rexx, idx = int) public static signals IllegalArgumentException
return caesar(input, int(26) - idx, isFalse)
method caesar_encipher(input = Rexx, idx = int, opt = Rexx) public static signals IllegalArgumentException
return caesar(input, idx, opt)
method caesar_decipher(input = Rexx, idx = int, opt = Rexx) public static signals IllegalArgumentException
return caesar(input, int(26) - idx, opt)
method caesar(input = Rexx, idx = int, opt = Rexx) public static signals IllegalArgumentException
if opt.upper.abbrev('U') >= 1 then caps = isTrue
else caps = isFalse
return caesar(input, idx, caps)
method caesar(input = Rexx, idx = int) public static signals IllegalArgumentException
return caesar(input, idx, isFalse)
method isTrue public static returns boolean
return (1 == 1)
method isFalse public static returns boolean
return \isTrue</lang>
Caesar cipher, key: 1 The five boxing wizards jump quickly Uif gjwf cpyjoh xjabset kvnq rvjdlmz The five boxing wizards jump quickly Caesar cipher, key: 2 The five boxing wizards jump quickly Vjg hkxg dqzkpi ykbctfu lwor swkemna The five boxing wizards jump quickly Caesar cipher, key: 20 The five boxing wizards jump quickly Nby zcpy vircha qctulxm dogj kocwefs The five boxing wizards jump quickly Caesar cipher, key: 25 The five boxing wizards jump quickly Sgd ehud anwhmf vhyzqcr itlo pthbjkx The five boxing wizards jump quickly Caesar cipher, key: 13 The five boxing wizards jump quickly Gur svir obkvat jvmneqf whzc dhvpxyl The five boxing wizards jump quickly Rot-13: The five boxing wizards jump quickly Gur svir obkvat jvmneqf whzc dhvpxyl The five boxing wizards jump quickly Caesar cipher, key: 1 Attack at dawn! Buubdl bu ebxo! Attack at dawn! Caesar cipher, key: 2 Attack at dawn! Cvvcem cv fcyp! Attack at dawn! Caesar cipher, key: 20 Attack at dawn! Unnuwe un xuqh! Attack at dawn! Caesar cipher, key: 25 Attack at dawn! Zsszbj zs czvm! Attack at dawn! Caesar cipher, key: 13 Attack at dawn! Nggnpx ng qnja! Attack at dawn! Rot-13: Attack at dawn! Nggnpx ng qnja! Attack at dawn! Caesar cipher, key: 1 HI IJ HI Caesar cipher, key: 2 HI JK HI Caesar cipher, key: 20 HI BC HI Caesar cipher, key: 25 HI GH HI Caesar cipher, key: 13 HI UV HI Rot-13: HI UV HI
Nim
<lang nim>import strutils
proc caesar(s: string, k: int, decode = false): string =
var k = if decode: 26 - k else: k
result = ""
for i in toUpper(s):
if ord(i) >= 65 and ord(i) <= 90:
result.add(chr((ord(i) - 65 + k) mod 26 + 65))
let msg = "The quick brown fox jumped over the lazy dogs" echo msg let enc = caesar(msg, 11) echo enc echo caesar(enc, 11, decode = true)</lang>
Oberon-2
Works with oo2c version2 <lang oberon2> MODULE Caesar; IMPORT
Out;
CONST
encode* = 1; decode* = -1;
VAR
text,cipher: POINTER TO ARRAY OF CHAR;
PROCEDURE Cipher*(txt: ARRAY OF CHAR; key: INTEGER; op: INTEGER; VAR cipher: ARRAY OF CHAR);
VAR
i: LONGINT;
BEGIN
i := 0;
WHILE i < LEN(txt) - 1 DO
IF (txt[i] >= 'A') & (txt[i] <= 'Z') THEN
cipher[i] := CHR(ORD('A') + ((ORD(txt[i]) - ORD('A') + (key * op))) MOD 26)
ELSIF (txt[i] >= 'a') & (txt[i] <= 'z') THEN
cipher[i] := CHR(ORD('a') + ((ORD(txt[i]) - ORD('a') + (key * op))) MOD 26)
ELSE
cipher[i] := txt[i]
END;
INC(i)
END;
cipher[i] := 0X
END Cipher;
BEGIN
NEW(text,3);NEW(cipher,3);
COPY("HI",text^);
Out.String(text^);Out.String(" =e=> ");
Cipher(text^,2,encode,cipher^);
Out.String(cipher^);
COPY(cipher^,text^);
Cipher(text^,2,decode,cipher^);
Out.String(" =d=> ");Out.String(cipher^);Out.Ln;
COPY("ZA",text^);
Out.String(text^);Out.String(" =e=> ");
Cipher(text^,2,encode,cipher^);
Out.String(cipher^);
COPY(cipher^,text^);
Cipher(text^,2,decode,cipher^);
Out.String(" =d=> ");Out.String(cipher^);Out.Ln;
NEW(text,37);NEW(cipher,37);
COPY("The five boxing wizards jump quickly",text^);
Out.String(text^);Out.String(" =e=> ");
Cipher(text^,3,encode,cipher^);
Out.String(cipher^);
COPY(cipher^,text^);
Cipher(text^,3,decode,cipher^);
Out.String(" =d=> ");Out.String(cipher^);Out.Ln;
END Caesar. </lang> Output:
HI =e=> JK =d=> HI ZA =e=> BC =d=> ZA The five boxing wizards jump quickly =e=> Wkh ilyh eralqj zlcdugv mxps txlfnob =d=> The five boxing wizards jump quickly
Objeck
<lang objeck> class Caesar {
function : native : Encode(enc : String, offset : Int) ~ String {
offset := offset % 26 + 26;
encoded := "";
enc := enc->ToLower();
each(i : enc) {
c := enc->Get(i);
if(c->IsChar()) {
j := (c - 'a' + offset) % 26;
encoded->Append(j + 'a');
}
else {
encoded->Append(c);
};
};
return encoded;
}
function : Decode(enc : String, offset : Int) ~ String {
return Encode(enc, offset * -1);
}
function : Main(args : String[]) ~ Nil {
enc := Encode("The quick brown fox Jumped over the lazy Dog", 12);
enc->PrintLine();
Decode(enc, 12)->PrintLine();
}
} </lang>
- Output:
ftq cguow ndaiz raj vgybqp ahqd ftq xmlk pas the quick brown fox jumped over the lazy dog
OCaml
<lang ocaml>let islower c =
c >= 'a' && c <= 'z'
let isupper c =
c >= 'A' && c <= 'Z'
let rot x str =
let upchars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
and lowchars = "abcdefghijklmnopqrstuvwxyz" in
let rec decal x =
if x < 0 then decal (x + 26) else x
in
let x = (decal x) mod 26 in
let decal_up = x - (int_of_char 'A')
and decal_low = x - (int_of_char 'a') in
String.map (fun c ->
if islower c then
let j = ((int_of_char c) + decal_low) mod 26 in
lowchars.[j]
else if isupper c then
let j = ((int_of_char c) + decal_up) mod 26 in
upchars.[j]
else
c
) str</lang>
<lang ocaml>let () =
let key = 3 in let orig = "The five boxing wizards jump quickly" in let enciphered = rot key orig in print_endline enciphered; let deciphered = rot (- key) enciphered in print_endline deciphered; Printf.printf "equal: %b\n" (orig = deciphered)
- </lang>
- Output:
$ ocaml caesar.ml Wkh ilyh eralqj zlcdugv mxps txlfnob The five boxing wizards jump quickly equal: true
Oforth
<lang Oforth>: ceasar(c, key)
c dup isLetter ifFalse: [ return ] isUpper ifTrue: [ 'A' ] else: [ 'a' ] c key + over - 26 mod + ;
- cipherE(s, key) s map(#[ key ceasar ]) charsAsString ;
- cipherD(s, key) cipherE(s, 26 key - ) ;</lang>
- Output:
>cipherE("Pack my box with five dozen liquor jugs.", 5) println
Ufhp rd gtc bnym knaj itejs qnvztw ozlx.
ok
>cipherD("Ufhp rd gtc bnym knaj itejs qnvztw ozlx.", 5) println
Pack my box with five dozen liquor jugs.
OOC
<lang ooc>main: func (args: String[]) {
shift := args[1] toInt()
if (args length != 3) {
"Usage: #{args[0]} [number] [sentence]" println()
"Incorrect number of arguments." println()
} else if (!shift && args[1] != "0"){
"Usage: #{args[0]} [number] [sentence]" println()
"Number is not a valid number." println()
} else {
str := ""
for (c in args[2]) {
if (c alpha?()) {
c = (c lower?() ? 'a' : 'A') + (26 + c toLower() - 'a' + shift) % 26
}
str += c
}
str println()
}
}</lang>
- Output:
$ ./caesar 8 "This should be a fairly original sentence." Bpqa apwctl jm i niqztg wzqoqvit amvbmvkm. $ ./caesar -9 "Yet another, fairly original sentence!" Pvk refkyvi, wrzicp fizxzerc jvekvetv!
PARI/GP
<lang parigp>enc(s,n)={
Strchr(Vecsmall(apply(k->if(k>96&&k<123,(k+n-97)%26+97, if(k>64&&k<91, (k+n-65)%26+65, k)), Vec(Vecsmall(s)))))
}; dec(s,n)=enc(s,-n);</lang>
Pascal
<lang pascal>Program CaesarCipher(output);
procedure encrypt(var message: string; key: integer);
var
i: integer;
begin
for i := 1 to length(message) do
case message[i] of
'A'..'Z': message[i] := chr(ord('A') + (ord(message[i]) - ord('A') + key) mod 26);
'a'..'z': message[i] := chr(ord('a') + (ord(message[i]) - ord('a') + key) mod 26);
end;
end;
procedure decrypt(var message: string; key: integer);
var
i: integer;
begin
for i := 1 to length(message) do
case message[i] of
'A'..'Z': message[i] := chr(ord('A') + (ord(message[i]) - ord('A') - key + 26) mod 26);
'a'..'z': message[i] := chr(ord('a') + (ord(message[i]) - ord('a') - key + 26) mod 26);
end;
end;
var
key: integer; message: string;
begin
key := 3;
message := 'The five boxing wizards jump quickly';
writeln ('Original message: ', message);
encrypt(message, key);
writeln ('Encrypted message: ', message);
decrypt(message, key);
writeln ('Decrypted message: ', message);
readln;
end.</lang>
- Output:
>: ./CaesarCipher Original message: The five boxing wizards jump quickly Encrypted message: Wkh ilyh eralqj zlcdugv mxps txlfnob Decrypted message: The five boxing wizards jump quickly >:
Perl
<lang Perl>sub caesar {
my ($message, $key, $decode) = @_;
$key = 26 - $key if $decode;
$message =~ s/([A-Z])/chr(((ord(uc $1) - 65 + $key) % 26) + 65)/geir;
}
my $msg = 'THE FIVE BOXING WIZARDS JUMP QUICKLY'; my $enc = caesar($msg, 10); my $dec = caesar($enc, 10, 'decode');
print "msg: $msg\nenc: $enc\ndec: $dec\n"; </lang>
- Output:
msg: THE FIVE BOXING WIZARDS JUMP QUICKLY enc: DRO PSFO LYHSXQ GSJKBNC TEWZ AESMUVI dec: THE FIVE BOXING WIZARDS JUMP QUICKLY
Phix
with javascript_semantics sequence alpha_b = repeat(0,255) alpha_b['A'..'Z'] = 'A' alpha_b['a'..'z'] = 'a' function caesar(string s, integer key) integer ch, base for i=1 to length(s) do ch = s[i] base = alpha_b[ch] if base then s[i] = base+remainder(ch-base+key,26) end if end for return s end function string s = "One fine day in the middle of the night, two dead men got up to fight. \n"& "Back to back they faced each other, drew their swords and shot each other. %^&*()[", e = caesar(s,5), r = caesar(e,26-5) ?e ?r
- Output:
Tsj knsj ifd ns ymj rniiqj tk ymj snlmy, ybt ijfi rjs lty zu yt knlmy. Gfhp yt gfhp ymjd kfhji jfhm tymjw, iwjb ymjnw xbtwix fsi xmty jfhm tymjw. %^&*()[ One fine day in the middle of the night, two dead men got up to fight. Back to back they faced each other, drew their swords and shot each other. %^&*()[
PHP
<lang php><?php function caesarEncode( $message, $key ){
$plaintext = strtolower( $message );
$ciphertext = "";
$ascii_a = ord( 'a' );
$ascii_z = ord( 'z' );
while( strlen( $plaintext ) ){
$char = ord( $plaintext );
if( $char >= $ascii_a && $char <= $ascii_z ){
$char = ( ( $key + $char - $ascii_a ) % 26 ) + $ascii_a;
}
$plaintext = substr( $plaintext, 1 );
$ciphertext .= chr( $char );
}
return $ciphertext;
}
echo caesarEncode( "The quick brown fox Jumped over the lazy Dog", 12 ), "\n"; ?></lang>
- Output:
ftq cguow ndaiz raj vgybqp ahqd ftq xmlk pas
Or, using PHP's strtr() built-in function
<lang php><?php
function caesarEncode($message, $key) {
$from = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'; $to = substr($from, $key) . substr($from, 0, $key); return strtr($message, $from, $to);
}
echo caesarEncode('THE QUICK BROWN FOX JUMPED OVER THE LAZY DOG', 12), PHP_EOL;</lang>
- Output:
FTQ CGUOW NDAIZ RAJ VGYBQP AHQD FTQ XMLK PAS
Picat
<lang Picat>main =>
S = "All human beings are born free and equal in dignity and rights.", println(S), println(caesar(S,5)), println(caesar(caesar(S,5),-5)), nl.
caesar(String, N) = Cipher =>
Lower = [chr(I): I in 97..122], Upper = [chr(I): I in 65..90], M = create_map(Lower, Upper, N), % If a char is not in a..zA..z then show it as it is. Cipher := [M.get(C,C) : C in String].
create_map(Lower,Upper, N) = M =>
M = new_map(), Len = Lower.length, foreach(I in 1..Len) II = (N+I) mod Len, if II == 0 then II := Len end, % Adjust for 1 based M.put(Upper[I],Upper[II]), M.put(Lower[I],Lower[II]) end.
</lang>
- Output:
Picat> main All human beings are born free and equal in dignity and rights. Fqq mzrfs gjnslx fwj gtws kwjj fsi jvzfq ns inlsnyd fsi wnlmyx. All human beings are born free and equal in dignity and rights.
PicoLisp
<lang PicoLisp>(setq *Letters (apply circ (mapcar char (range 65 90))))
(de caesar (Str Key)
(pack
(mapcar '((C) (cadr (nth (member C *Letters) Key)))
(chop (uppc Str)) ) ) )</lang>
Test:
: (caesar "IBM" 25) -> "HAL" : (caesar @ 1) -> "IBM" : (caesar "The quick brown fox jumped over the lazy dog's back" 7) -> "AOLXBPJRIYVDUMVEQBTWLKVCLYAOLSHGFKVNZIHJR" : (caesar @ (- 26 7)) -> "THEQUICKBROWNFOXJUMPEDOVERTHELAZYDOGSBACK"
Pike
Pike has built in support for substitution cryptos in the Crypto module. It's possible to set the desired alphabet, but the default a-z matches the Caesar range. <lang Pike>object c = Crypto.Substitution()->set_rot_key(2); string msg = "The quick brown fox jumped over the lazy dogs"; string msg_s2 = c->encrypt(msg); c->set_rot_key(11); string msg_s11 = c->encrypt(msg); string decoded = c->decrypt(msg_s11);
write("%s\n%s\n%s\n%s\n", msg, msg_s2, msg_s11, decoded);</lang>
- Output:
The quick brown fox jumped over the lazy dogs Vjg swkem dtqyp hqz lworgf qxgt vjg ncba fqiu Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozrd The quick brown fox jumped over the lazy dogs
PL/I
<lang pli>caesar: procedure options (main);
declare cypher_string character (52) static initial
((2)'ABCDEFGHIJKLMNOPQRSTUVWXYZ');
declare (text, encyphered_text) character (100) varying,
offset fixed binary;
get edit (text) (L); /* Read in one line of text */
get list (offset);
if offset < 1 | offset > 25 then signal error;
put skip list ('Plain text=', text);
encyphered_text = translate(text, substr(cypher_string, offset+1, 26),
'ABCDEFGHIJKLMNOPQRSTUVWXYZ' );
put skip list ('Encyphered text=', encyphered_text);
text = translate(encyphered_text, substr(cypher_string, 27-offset, 26),
'ABCDEFGHIJKLMNOPQRSTUVWXYZ' );
put skip list ('Decyphered text=', text);
end caesar;</lang>
- Output:
with offset of 5
Plain text= THEQUICKBROWNFOXJUMPSOVERTHELAZYDOG Encyphered text= YMJVZNHPGWTBSKTCOZRUXTAJWYMJQFEDITL Decyphered text= THEQUICKBROWNFOXJUMPSOVERTHELAZYDOG
PowerShell
<lang Powershell># Author: M. McNabb function Get-CaesarCipher { Param ( [Parameter( Mandatory=$true,ValueFromPipeline=$true)] [string] $Text,
[ValidateRange(1,25)] [int] $Key = 1,
[switch] $Decode )
begin {
$LowerAlpha = [char]'a'..[char]'z' $UpperAlpha = [char]'A'..[char]'Z'
}
process {
$Chars = $Text.ToCharArray()
function encode
{
param
(
$Char,
$Alpha = [char]'a'..[char]'z'
)
$Index = $Alpha.IndexOf([int]$Char)
$NewIndex = ($Index + $Key) - $Alpha.Length
$Alpha[$NewIndex]
}
function decode
{
param
(
$Char,
$Alpha = [char]'a'..[char]'z'
)
$Index = $Alpha.IndexOf([int]$Char)
$int = $Index - $Key
if ($int -lt 0) {$NewIndex = $int + $Alpha.Length}
else {$NewIndex = $int}
$Alpha[$NewIndex]
}
foreach ($Char in $Chars)
{
if ([int]$Char -in $LowerAlpha)
{
if ($Decode) {$Char = decode $Char}
else {$Char = encode $Char}
}
elseif ([int]$Char -in $UpperAlpha)
{
if ($Decode) {$Char = decode $Char $UpperAlpha}
else {$Char = encode $Char $UpperAlpha}
}
$Char = [char]$Char
[string]$OutText += $Char
}
$OutText $OutText = $null
} }</lang> Usage examples:
Encode: PS C:\> 'Pack my box with five dozen liquor jugs.' | Get-CaesarCipher -key 3 Sdfn pb era zlwk ilyh grchq oltxru mxjv. Decode: PS C:\> 'Sdfn pb era zlwk ilyh grchq oltxru mxjv.' | Get-CaesarCipher -key 3 -Decode Pack my box with five dozen liquor jugs. Encode lines of text from a file: PS C:\> Get-Content C:\Text.txt | Get-CaesarCipher -key 10 Vsxo yxo. Vsxo dgy! Vsxo drboo;
Prolog
<lang Prolog>:- use_module(library(clpfd)).
caesar :- L1 = "The five boxing wizards jump quickly", writef("Original : %s\n", [L1]),
% encryption of the sentence encoding(3, L1, L2) , writef("Encoding : %s\n", [L2]),
% deciphering on the encoded sentence encoding(3, L3, L2), writef("Decoding : %s\n", [L3]).
% encoding/decoding of a sentence encoding(Key, L1, L2) :- maplist(caesar_cipher(Key), L1, L2).
caesar_cipher(_, 32, 32) :- !.
caesar_cipher(Key, V1, V2) :- V #= Key + V1,
% we verify that we are in the limits of A-Z and a-z. ((V1 #=< 0'Z #/\ V #> 0'Z) #\/ (V1 #=< 0'z #/\ V #> 0'z) #\/ (V1 #< 0'A #/\ V2 #>= 0'A)#\/ (V1 #< 0'a #/\ V2 #>= 0'a)) #==> A,
% if we are not in these limits A is 1, otherwise 0. V2 #= V - A * 26,
% compute values of V1 and V2 label([A, V1, V2]).</lang>
- Output:
?- caesar. Original : The five boxing wizards jump quickly Encoding : Wkh ilyh eralqj zlcdugv mxps txlfnob Decoding : The five boxing wizards jump quickly true .
PureBasic
The case is maintained for alphabetic characters (uppercase/lowercase input = uppercase/lowercase output) while non-alphabetic characters, if present are included and left unchanged in the result. <lang PureBasic>Procedure.s CC_encrypt(plainText.s, key, reverse = 0)
;if reverse <> 0 then reverse the encryption (decrypt)
If reverse: reverse = 26: key = 26 - key: EndIf
Static alphabet$ = "ABCEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz"
Protected result.s, i, length = Len(plainText), letter.s, legal
If key < 1 Or key > 25: ProcedureReturn: EndIf ;keep key in range
For i = 1 To length
letter = Mid(plainText, i, 1)
legal = FindString(alphabet$, letter, 1 + reverse)
If legal
result + Mid(alphabet$, legal + key, 1)
Else
result + letter
EndIf
Next
ProcedureReturn result
EndProcedure
Procedure.s CC_decrypt(cypherText.s, key)
ProcedureReturn CC_encrypt(cypherText, key, 1)
EndProcedure
If OpenConsole()
Define key, plainText.s, encryptedText.s, decryptedText.s
key = Random(24) + 1 ;get a random key in the range 1 -> 25
plainText = "The quick brown fox jumped over the lazy dogs.": PrintN(RSet("Plain text = ", 17) + #DQUOTE$ + plainText + #DQUOTE$)
encryptedText = CC_encrypt(plainText, key): PrintN(RSet("Encrypted text = ", 17) + #DQUOTE$ + encryptedText + #DQUOTE$)
decryptedText = CC_decrypt(encryptedText, key): PrintN(RSet("Decrypted text = ", 17) + #DQUOTE$ + decryptedText + #DQUOTE$)
Print(#CRLF$ + #CRLF$ + "Press ENTER to exit"): Input()
CloseConsole()
EndIf</lang>
- Output:
Plain text = "The quick brown fox jumped over the lazy dogs." Encrypted text = "Znk waoiq hxuct lud pasvkj ubkx znk rgfe jumy." Decrypted text = "the quick brown fox jumped over the lazy dogs."
Alternate solution
Here is an alternate and more advanced form of the encrypt procedure. It improves on the simple version in terms of speed, in case Caesar is using the cipher on some very long documents. It is meant to replace the encrypt procedure in the previous code and produces identical results. <lang PureBasic>Procedure.s CC_encrypt(text.s, key, reverse = 0)
;if reverse <> 0 then reverse the encryption (decrypt)
Protected i, *letter.Character, *resultLetter.Character, result.s = Space(Len(text))
If reverse: key = 26 - key: EndIf
If key < 1 Or key > 25: ProcedureReturn: EndIf ;exit if key out of range
*letter = @text: *resultLetter = @result
While *letter\c
Select *letter\c
Case 'A' To 'Z'
*resultLetter\c = ((*letter\c - 65 + key) % 26) + 65
Case 'a' To 'z'
*resultLetter\c = ((*letter\c - 97 + key) % 26) + 97
Default
*resultLetter\c = *letter\c
EndSelect
*letter + SizeOf(Character): *resultLetter + SizeOf(Character)
Wend
ProcedureReturn result
EndProcedure</lang>
Python
<lang Python>def caesar(s, k, decode = False): if decode: k = 26 - k return "".join([chr((ord(i) - 65 + k) % 26 + 65) for i in s.upper() if ord(i) >= 65 and ord(i) <= 90 ])
msg = "The quick brown fox jumped over the lazy dogs" print msg enc = caesar(msg, 11) print enc print caesar(enc, 11, decode = True)</lang>
- Output:
The quick brown fox jumped over the lazy dogs ESPBFTNVMCZHYQZIUFXAPOZGPCESPWLKJOZRD THEQUICKBROWNFOXJUMPEDOVERTHELAZYDOGS
Alternate solution
(for 3.x change string.maketrans to str.maketrans)
<lang python>import string def caesar(s, k, decode = False):
if decode: k = 26 - k
return s.translate(
string.maketrans(
string.ascii_uppercase + string.ascii_lowercase,
string.ascii_uppercase[k:] + string.ascii_uppercase[:k] +
string.ascii_lowercase[k:] + string.ascii_lowercase[:k]
)
)
msg = "The quick brown fox jumped over the lazy dogs" print msg enc = caesar(msg, 11) print enc print caesar(enc, 11, decode = True)</lang>
- Output:
The quick brown fox jumped over the lazy dogs Esp bftnv mczhy qzi ufxapo zgpc esp wlkj ozrd The quick brown fox jumped over the lazy dogs
Variant with memoization of translation tables
<lang python>import string def caesar(s, k = 13, decode = False, *, memo={}):
if decode: k = 26 - k
k = k % 26
table = memo.get(k)
if table is None:
table = memo[k] = str.maketrans(
string.ascii_uppercase + string.ascii_lowercase,
string.ascii_uppercase[k:] + string.ascii_uppercase[:k] +
string.ascii_lowercase[k:] + string.ascii_lowercase[:k])
return s.translate(table)</lang>
A compact alternative solution <lang python> from string import ascii_uppercase as abc
def caesar(s, k, decode = False):
trans = dict(zip(abc, abc[(k,26-k)[decode]:] + abc[:(k,26-k)[decode]])) return .join(trans[L] for L in s.upper() if L in abc)
msg = "The quick brown fox jumped over the lazy dogs" print(caesar(msg, 11)) print(caesar(caesar(msg, 11), 11, True)) </lang>
- Output:
ESPBFTNVMCZHYQZIUFXAPOZGPCESPWLKJOZRD THEQUICKBROWNFOXJUMPEDOVERTHELAZYDOGS
QBasic
Note that TrueBasic uses '!' for comments
<lang QBasic>LET dec$ = "" LET tipo$ = "cleartext "
PRINT "If decrypting enter 'd' -- else press enter "; INPUT dec$ PRINT "Enter offset "; INPUT llave
IF dec$ = "d" THEN
LET llave = 26 - llave LET tipo$ = "ciphertext "
END IF
PRINT "Enter "; tipo$; INPUT cadena$
LET cadena$ = UCASE$(cadena$) LET longitud = LEN(cadena$)
FOR i = 1 TO longitud
LET iTemp = ASC(MID$(cadena$,i,1)) 'QBasic
'LET itemp = ORD((cadena$)[i:i+1-1][1:1]) 'True BASIC
IF iTemp > 64 AND iTemp < 91 THEN
LET iTemp = ((iTemp - 65) + llave) MOD 26 'QBasic
'LET iTemp = MOD(((iTemp - 65) + llave), 26) 'True BASIC
PRINT CHR$(iTemp + 65);
ELSE
PRINT CHR$(iTemp);
END IF
NEXT i END</lang>
Quackery
<lang Quackery> [ dup upper != ] is lower? ( c --> b )
[ dup lower != ] is upper? ( c --> b )
[ swap $ "" unrot witheach
[ dup lower? iff
[ over +
dup lower? not if
[ 26 - ] ]
else
[ dup upper? if
[ over +
dup upper? not if
[ 26 - ] ] ]
rot swap join swap ]
drop ] is caesar ( $ --> $ )
[ 26 swap - ] is decode ( n --> n )
$ "Fere libenter homines id quod volunt credunt." dup echo$ cr 23 caesar dup echo$ cr 23 decode caesar echo$ cr</Lang>
- Output:
Fere libenter homines id quod volunt credunt. Cbob ifybkqbo eljfkbp fa nrla slirkq zobarkq. Fere libenter homines id quod volunt credunt.
R
This is a generalization of the Rot-13 solution for R at: http://rosettacode.org/wiki/Rot-13#R . <lang R>
- based on Rot-13 solution: http://rosettacode.org/wiki/Rot-13#R
ceasar <- function(x, key) {
# if key is negative, wrap to be positive
if (key < 0) {
key <- 26 + key
}
old <- paste(letters, LETTERS, collapse="", sep="")
new <- paste(substr(old, key * 2 + 1, 52), substr(old, 1, key * 2), sep="")
chartr(old, new, x)
}
- simple examples from description
print(ceasar("hi",2)) print(ceasar("hi",20))
- more advanced example
key <- 3 plaintext <- "The five boxing wizards jump quickly." cyphertext <- ceasar(plaintext, key) decrypted <- ceasar(cyphertext, -key)
print(paste(" Plain Text: ", plaintext, sep="")) print(paste(" Cypher Text: ", cyphertext, sep="")) print(paste("Decrypted Text: ", decrypted, sep=""))
</lang>
- Output:
> print(ceasar("hi",2))
[1] "jk"
> print(ceasar("hi",20))
[1] "bc"
> print(paste("Plain Text: ", plaintext, sep=""))
[1] "Plain Text: The five boxing wizards jump quickly."
> print(paste("Cypher Text: ", cyphertext, sep=""))
[1] "Cypher Text: Wkh ilyh eralqj zlcdugv mxps txlfnob."
> print(paste("Decrypted Text: ", decrypted, sep=""))
[1] "Decrypted Text: The five boxing wizards jump quickly."
Racket
<lang racket>
- lang racket
(define A (char->integer #\A)) (define Z (char->integer #\Z)) (define a (char->integer #\a)) (define z (char->integer #\z))
(define (rotate c n)
(define cnum (char->integer c))
(define (shift base) (integer->char (+ base (modulo (+ n (- cnum base)) 26))))
(cond [(<= A cnum Z) (shift A)]
[(<= a cnum z) (shift a)]
[else c]))
(define (caesar s n)
(list->string (for/list ([c (in-string s)]) (rotate c n))))
(define (encrypt s) (caesar s 1)) (define (decrypt s) (caesar s -1)) </lang> Example:
> (define s (encrypt "The five boxing wizards jump quickly.")) > s "Uif gjwf cpyjoh xjabset kvnq rvjdlmz." > (decrypt s) "The five boxing wizards jump quickly."
Raku
(formerly Perl 6)
<lang perl6>my @alpha = 'A' .. 'Z'; sub encrypt ( $key where 1..25, $plaintext ) {
$plaintext.trans( @alpha Z=> @alpha.rotate($key) );
} sub decrypt ( $key where 1..25, $cyphertext ) {
$cyphertext.trans( @alpha.rotate($key) Z=> @alpha );
}
my $original = 'THE FIVE BOXING WIZARDS JUMP QUICKLY'; my $en = encrypt( 13, $original ); my $de = decrypt( 13, $en );
.say for $original, $en, $de;
say 'OK' if $original eq all( map { .&decrypt(.&encrypt($original)) }, 1..25 );</lang>
- Output:
THE FIVE BOXING WIZARDS JUMP QUICKLY GUR SVIR OBKVAT JVMNEQF WHZC DHVPXYL THE FIVE BOXING WIZARDS JUMP QUICKLY OK
Red
<lang red> Red ["Ceasar Cipher"]
rot: func [
char [char!] key [number!] ofs [char!]
][
to-char key + char - ofs // 26 + ofs
]
caesar: function [
src [string!] key [integer!]
][
lower: charset [#"a" - #"z"]
upper: charset [#"A" - #"Z"]
parse src [
any [
change s: [lower (o: #"a") | upper (o: #"A")] (rot s/1 key o)
| skip
]
]
src
]
encrypt: :caesar decrypt: func spec-of :caesar [caesar src negate key] </lang>
>> print encrypt "Ceasar Cipher" 4 Giewev Gmtliv >> print decrypt "Giewev Gmtliv" 4 Ceasar Cipher >>
Retro
Retro provides a number of classical cyphers in the crypto' library. This implementation is from the library. <lang Retro>{{
variable offset : rotate ( cb-c ) tuck - @offset + 26 mod + ; : rotate? ( c-c ) dup 'a 'z within [ 'a rotate ] ifTrue dup 'A 'Z within [ 'A rotate ] ifTrue ;
---reveal---
: ceaser ( $n-$ ) !offset dup [ [ @ rotate? ] sip ! ] ^types'STRING each@ ;
}}
( Example ) "THEYBROKEOURCIPHEREVERYONECANREADTHIS" 3 ceaser ( returns encrypted string ) 23 ceaser ( returns decrypted string )</lang>
REXX
only Latin letters
This version conforms to the task's restrictions. <lang rexx>/*REXX program supports the Caesar cypher for the Latin alphabet only, no punctuation */ /*──────────── or blanks allowed, all lowercase Latin letters are treated as uppercase.*/ parse arg key .; arg . p /*get key & uppercased text to be used.*/ p= space(p, 0) /*elide any and all spaces (blanks). */
say 'Caesar cypher key:' key /*echo the Caesar cypher key to console*/
say ' plain text:' p /* " " plain text " " */
y= Caesar(p, key); say ' cyphered:' y /* " " cyphered text " " */ z= Caesar(y,-key); say ' uncyphered:' z /* " " uncyphered text " " */ if z\==p then say "plain text doesn't match uncyphered cyphered text." exit 0 /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ Caesar: procedure; arg s,k; @= 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
ak= abs(k) /*obtain the absolute value of the key.*/
L= length(@) /*obtain the length of the @ string. */
if ak>length(@)-1 | k==0 then call err k 'key is invalid.'
_= verify(s, @) /*any illegal characters specified ? */
if _\==0 then call err 'unsupported character:' substr(s, _, 1)
if k>0 then ky= k + 1 /*either cypher it, or ··· */
else ky= L + 1 - ak /* decypher it. */
return translate(s, substr(@ || @, ky, L), @) /*return the processed text.*/
/*──────────────────────────────────────────────────────────────────────────────────────*/ err: say; say '***error***'; say; say arg(1); say; exit 13</lang>
- output when using the input of: 22 The definition of a trivial program is one that has no bugs
Caesar cypher key: 22
plain text: THEDEFINITIONOFATRIVIALPROGRAMISONETHATHASNOBUGS
cyphered: PDAZABEJEPEKJKBWPNEREWHLNKCNWIEOKJAPDWPDWOJKXQCO
uncyphered: THEDEFINITIONOFATRIVIALPROGRAMISONETHATHASNOBUGS
most characters
This version allows upper and lowercase Latin alphabet as well as all the characters on the standard (computer) keyboard including blanks. <lang rexx>/*REXX program supports the Caesar cypher for most keyboard characters including blanks.*/ parse arg key p /*get key and the text to be cyphered. */
say 'Caesar cypher key:' key /*echo the Caesar cypher key to console*/
say ' plain text:' p /* " " plain text " " */
y= Caesar(p, key); say ' cyphered:' y /* " " cyphered text " " */ z= Caesar(y,-key); say ' uncyphered:' z /* " " uncyphered text " " */ if z\==p then say "plain text doesn't match uncyphered cyphered text." exit 0 /*stick a fork in it, we're all done. */ /*──────────────────────────────────────────────────────────────────────────────────────*/ Caesar: procedure; parse arg s,k; @= 'abcdefghijklmnopqrstuvwxyz'
@= translate(@)@"0123456789(){}[]<>'" /*add uppercase, digits, group symbols.*/
@= @'~!@#$%^&*_+:";?,./`-= ' /*also add other characters to the list*/
L= length(@) /*obtain the length of the @ string. */
ak= abs(k) /*obtain the absolute value of the key.*/
if ak>length(@)-1 | k==0 then call err k 'key is invalid.'
_= verify(s,@) /*any illegal characters specified ? */
if _\==0 then call err 'unsupported character:' substr(s, _, 1)
if k>0 then ky= k + 1 /*either cypher it, or ··· */
else ky= L + 1 - ak /* decypher it. */
return translate(s, substr(@ || @, ky, L), @) /*return the processed text.*/
/*──────────────────────────────────────────────────────────────────────────────────────*/ err: say; say '***error***'; say; say arg(1); say; exit 13</lang>
- output when using the input of: 31 Batman's hood is called a "cowl" (old meaning).
Caesar cypher key: 31
plain text: Batman's hood is called a "cowl" (old meaning).
cyphered: g5^>5~e%d{!!8d}%d75<<98d5dU7!_<UdA!<8d>95~}~)BY
uncyphered: Batman's hood is called a "cowl" (old meaning).
Ring
<lang ring>
- Project : Caesar cipher
cipher = "pack my box with five dozen liquor jugs" abc = "abcdefghijklmnopqrstuvwxyz" see "text is to be encrypted:" + nl see cipher+ nl + nl str = "" key = random(24) + 1 see "key = " + key + nl + nl see "encrypted:" + nl caesarencode(cipher, key) see str + nl + nl cipher = str see "decrypted again:" + nl caesardecode(cipher, key) see str + nl
func caesarencode(cipher, key)
str = ""
for n = 1 to len(cipher)
if cipher[n] != " "
pos = substr(abc, cipher[n])
if pos + key < len(abc)
str = str + abc[pos + key]
else
if (pos+key)-len(abc) != 0
str = str + abc[(pos+key)%len(abc)]
else
str = str +abc[key+pos]
ok
ok
else
str = str + " "
ok
next
return str
func caesardecode(cipher, key)
str = ""
for n= 1 to len(cipher)
if cipher[n] != " "
pos = substr(abc, cipher[n])
if (pos - key) > 0 and pos != key
str = str + abc[pos - key]
loop
else
if pos = key
str = str + char(122)
else
str = str + abc[len(abc)-(key-pos)]
ok
ok
else
str = str + " "
ok
next
return str
</lang> Output:
text is to be encrypted: pack my box with five dozen liquor jugs key = 9 encrypted: yjlt vh kxg frcq oren mxinw urzdxa sdpb decrypted again: pack my box with five dozen liquor jugs
Ruby
<lang ruby>class String
ALFABET = ("A".."Z").to_a
def caesar_cipher(num) self.tr(ALFABET.join, ALFABET.rotate(num).join) end
end
- demo:
encypted = "THEYBROKEOURCIPHEREVERYONECANREADTHIS".caesar_cipher(3) decrypted = encypted.caesar_cipher(-3) </lang>
Run BASIC
<lang runbasic>input "Gimme a ofset:";ofst ' set any offset you like
a$ = "Pack my box with five dozen liquor jugs" print " Original: ";a$ a$ = cipher$(a$,ofst) print "Encrypted: ";a$ print "Decrypted: ";cipher$(a$,ofst+6)
FUNCTION cipher$(a$,ofst) for i = 1 to len(a$)
aa$ = mid$(a$,i,1) code$ = " " if aa$ <> " " then ua$ = upper$(aa$) a = asc(ua$) - 64 code$ = chr$((((a mod 26) + ofst) mod 26) + 65) if ua$ <> aa$ then code$ = lower$(code$) end if cipher$ = cipher$;code$
next i END FUNCTION</lang>
- Output:
Gimme a ofset:?9 Original: Pack my box with five dozen liquor jugs Encrypted: Zkmu wi lyh gsdr psfo nyjox vsaeyb teqc Decrypted: Pack my box with five dozen liquor jugs
Rust
This example shows proper error handling. It skips non-ASCII characters. <lang rust>use std::io::{self, Write}; use std::fmt::Display; use std::{env, process};
fn main() {
let shift: u8 = env::args().nth(1)
.unwrap_or_else(|| exit_err("No shift provided", 2))
.parse()
.unwrap_or_else(|e| exit_err(e, 3));
let plain = get_input()
.unwrap_or_else(|e| exit_err(&e, e.raw_os_error().unwrap_or(-1)));
let cipher = plain.chars()
.map(|c| {
let case = if c.is_uppercase() {'A'} else {'a'} as u8;
if c.is_alphabetic() { (((c as u8 - case + shift) % 26) + case) as char } else { c }
}).collect::<String>();
println!("Cipher text: {}", cipher.trim());
}
fn get_input() -> io::Result<String> {
print!("Plain text: ");
try!(io::stdout().flush());
let mut buf = String::new(); try!(io::stdin().read_line(&mut buf)); Ok(buf)
}
fn exit_err<T: Display>(msg: T, code: i32) -> ! {
let _ = writeln!(&mut io::stderr(), "ERROR: {}", msg);
process::exit(code);
}</lang>
Scala
<lang scala>object Caesar {
private val alphaU='A' to 'Z' private val alphaL='a' to 'z'
def encode(text:String, key:Int)=text.map{
case c if alphaU.contains(c) => rot(alphaU, c, key)
case c if alphaL.contains(c) => rot(alphaL, c, key)
case c => c
}
def decode(text:String, key:Int)=encode(text,-key)
private def rot(a:IndexedSeq[Char], c:Char, key:Int)=a((c-a.head+key+a.size)%a.size)
}</lang> <lang scala>val text="The five boxing wizards jump quickly" println("Plaintext => " + text) val encoded=Caesar.encode(text, 3) println("Ciphertext => " + encoded) println("Decrypted => " + Caesar.decode(encoded, 3))</lang>
- Output:
Plaintext => The five boxing wizards jump quickly Ciphertext => Wkh ilyh eralqj zlcdugv mxps txlfnob Decrypted => The five boxing wizards jump quickly
Alternate version
This version first creates non shifted and shifted character sequences and then encodes and decodes by indexing between those sequences. <lang scala>class Caeser(val key: Int) {
@annotation.tailrec private def rotate(p: Int, s: IndexedSeq[Char]): IndexedSeq[Char] = if (p < 0) rotate(s.length + p, s) else s.drop(p) ++ s.take(p)
val uc = 'A' to 'Z' val lc = 'a' to 'z' val as = uc ++ lc val bs = rotate(key, uc) ++ rotate(key, lc) def encode(c: Char) = if (as.contains(c)) bs(as.indexOf(c)) else c def decode(c: Char) = if (bs.contains(c)) as(bs.indexOf(c)) else c
}</lang>
<lang scala>val text = "The five boxing wizards jump quickly" val myCaeser = new Caeser(3) val encoded = text.map(c => myCaeser.encode(c)) println("Plaintext => " + text) println("Ciphertext => " + encoded) println("Decrypted => " + encoded.map(c => myCaeser.decode(c)))</lang>
- Output:
Plaintext => The five boxing wizards jump quickly Ciphertext => Wkh ilyh eralqj zlcdugv mxps txlfnob Decrypted => The five boxing wizards jump quickly
Scheme
<lang scheme>;
- Works with R7RS-compatible Schemes (e.g. Chibi).
- Also current versions of Chicken, Gauche and Kawa.
(cond-expand
(chicken (use srfi-13)) (gauche (use srfi-13)) (kawa (import (srfi :13))) (else (import (scheme base) (scheme write)))) ; R7RS
(define msg "The quick brown fox jumps over the lazy dog.")
(define key 13)
(define (caesar char)
(define A (char->integer #\A))
(define Z (char->integer #\Z))
(define a (char->integer #\a))
(define z (char->integer #\z))
(define c (char->integer char))
(integer->char
(cond ((<= A c Z) (+ A (modulo (+ key (- c A)) 26)))
((<= a c z) (+ a (modulo (+ key (- c a)) 26)))
(else c)))) ; Return other characters verbatim.
(display (string-map caesar msg)) (newline) </lang>
- Output:
Gur dhvpx oebja sbk whzcf bire gur ynml qbt.
sed
This code is roughly equivalent to the rot-13 cypher sed implementation, except that the conversion table is parameterized by a number and that the conversion done manually, instead of using `y///' command. <lang sed>#!/bin/sed -rf
- Input: <number 0..25>\ntext to encode
/^[0-9]+$/ { # validate a number and translate it to analog form s/$/;9876543210dddddddddd/ s/([0-9]);.*\1.{10}(.?)/\2/ s/2/11/ s/1/dddddddddd/g /[3-9]|d{25}d+/ { s/.*/Error: Key must be <= 25/ q } # append from-table s/$/\nabcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/ # .. and to-table s/$/abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/ # rotate to-table, lower and uppercase independently, removing one `d' at a time : rotate s/^d(.*\n[^Z]+Z)(.)(.{25})(.)(.{25})/\1\3\2\5\4/ t rotate s/\n// h d }
- use \n to mark character to convert
s/^/\n/
- append conversion table to pattern space
G
- loop
# look up converted character and place it instead of old one s/\n(.)(.*\n.*\1.{51}(.))/\n\3\2/ # advance \n even if prev. command fails, thus skip non-alphabetical characters /\n\n/! s/\n([^\n])/\1\n/ t loop s/\n\n.*//</lang>
- Output:
$ ./caesar.sed 3 The five boxing wizards jump quickly Wkh ilyh eralqj zlcdugv mxps txlfnob 23 Wkh ilyh eralqj zlcdugv mxps txlfnob The five boxing wizards jump quickly 26 Error: Key must be <= 25
Seed7
<lang seed7>$ include "seed7_05.s7i";
const func string: rot (in string: stri, in integer: encodingKey) is func
result
var string: encodedStri is "";
local
var char: ch is ' ';
var integer: index is 0;
begin
encodedStri := stri;
for ch key index range stri do
if ch >= 'a' and ch <= 'z' then
ch := chr((ord(ch) - ord('a') + encodingKey) rem 26 + ord('a'));
elsif ch >= 'A' and ch <= 'Z' then
ch := chr((ord(ch) - ord('A') + encodingKey) rem 26 + ord('A'));
end if;
encodedStri @:= [index] ch;
end for;
end func;
const proc: main is func
local
const integer: exampleKey is 3;
const string: testText is "The five boxing wizards jump quickly";
begin
writeln("Original: " <& testText);
writeln("Encrypted: " <& rot(testText, exampleKey));
writeln("Decrypted: " <& rot(rot(testText, exampleKey), 26 - exampleKey));
end func;</lang>
- Output:
Original: The five boxing wizards jump quickly Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob Decrypted: The five boxing wizards jump quickly
SequenceL
You only have to write an encrypt and decrypt function for characters. The semantics of Normalize Transpose allow those functions to be applied to strings. <lang sequencel>import <Utilities/Sequence.sl>; import <Utilities/Conversion.sl>;
lowerAlphabet := "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; upperAlphabet := "abcdefghijklmnopqrstuvwxyz";
caesarEncrypt(ch, key) := let correctAlphabet := lowerAlphabet when some(ch = lowerAlphabet) else upperAlphabet;
index := Sequence::firstIndexOf(correctAlphabet, ch);
newIndex := (index + key - 1) mod 26 + 1; in ch when not(some(ch = lowerAlphabet) or some(ch = upperAlphabet)) else correctAlphabet[newIndex];
caesarDecrypt(ch, key) := caesarEncrypt(ch, 26 - key);
main(args(2)) := let key := Conversion::stringToInt(args[2]); encrypted := caesarEncrypt(args[1], key); decrypted := caesarDecrypt(encrypted, key); in "Input: \t" ++ args[1] ++ "\n" ++ "Encrypted:\t" ++ encrypted ++ "\n" ++ "Decrypted:\t" ++ decrypted;</lang>
- Output:
cmd:> main.exe "Pack my box with five dozen liquor jugs." 5 "Original: Pack my box with five dozen liquor jugs. Encrypted: Ufhp rd gtc bnym knaj itejs qnvztw ozlx. Decrypted: Pack my box with five dozen liquor jugs."
Sidef
<lang ruby>func caesar(msg, key, decode=false) {
decode && (key = (26 - key));
msg.gsub(/([A-Z])/i, {|c| ((c.uc.ord - 65 + key) % 26) + 65 -> chr});
};
var msg = 'THE FIVE BOXING WIZARDS JUMP QUICKLY';
var enc = caesar(msg, 10); var dec = caesar(enc, 10, true);
say "msg: #{msg}"; say "enc: #{enc}"; say "dec: #{dec}";</lang>
- Output:
msg: THE FIVE BOXING WIZARDS JUMP QUICKLY enc: DRO PSFO LYHSXQ GSJKBNC TEWZ AESMUVI dec: THE FIVE BOXING WIZARDS JUMP QUICKLY
Sinclair ZX81 BASIC
Works with 1k of RAM. A negative key decodes. <lang basic> 10 INPUT KEY
20 INPUT T$ 30 LET C$="" 40 FOR I=1 TO LEN T$ 50 LET L$=T$(I) 60 IF L$<"A" OR L$>"Z" THEN GOTO 100 70 LET L$=CHR$ (CODE L$+KEY) 80 IF L$>"Z" THEN LET L$=CHR$ (CODE L$-26) 90 IF L$<"A" THEN LET L$=CHR$ (CODE L$+26)
100 LET C$=C$+L$ 110 NEXT I 120 PRINT C$</lang>
- Input:
12 GALLIA EST OMNIS DIVISA IN PARTES TRES
- Output:
SMXXUM QEF AYZUE PUHUEM UZ BMDFQE FDQE
- Input:
-12 SMXXUM QEF AYZUE PUHUEM UZ BMDFQE FDQE
- Output:
GALLIA EST OMNIS DIVISA IN PARTES TRES
Smalltalk
well, I'm lucky: the standard library already contains a rot:n method! <lang Smalltalk>'THE QUICK BROWN FOX' rot:3 -> 'WKH TXLFN EURZQ IRA' </lang> but if it wasn't, here is an implementation for other smalltalks: <lang smalltalk> !CharacterArray methodsFor:'encoding'! rot:n
^ self class
streamContents:[:aStream |
self do:[:char |
aStream nextPut:(char rot:n) ]]
!Character methodsFor:'encoding'!
rot:n
(self isLetter) ifTrue:[
self isLowercase ifTrue:[
^ 'abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz' at:(self-$a+1+n)
] ifFalse:[
^ 'ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ' at:(self-$A+1+n)
]
].
^ self
</lang>
SSEM
ASCII didn't exit in 1948, and the task specification explicitly says we only need to convert Roman capitals; so we adopt a simpler encoding, representing the letters of the alphabet from A=0 to Z=25.
The program will convert one character at a time. Load the character code into storage address 20, and the key into address 19. The machine will halt with the cyphered encoding in the accumulator. A negative (two's complement) key decodes.
This is in fact a general solution that will work equally well with alphabets of more or fewer than 26 characters: simply replace the constant 26 in storage address 18 with 22 for Hebrew, 24 for Greek, 28 for Arabic, 33 for Russian, etc. <lang ssem>00101000000000100000000000000000 0. -20 to c 11001000000000010000000000000000 1. Sub. 19 10101000000001100000000000000000 2. c to 21 10101000000000100000000000000000 3. -21 to c 00000000000000110000000000000000 4. Test 10001000000000000000000000000000 5. 17 to CI 10101000000001100000000000000000 6. c to 21 10101000000000100000000000000000 7. -21 to c 01001000000000010000000000000000 8. Sub. 18 10101000000001100000000000000000 9. c to 21 10101000000000100000000000000000 10. -21 to c 00000000000001110000000000000000 11. Stop 01001000000000010000000000000000 12. Sub. 18 00000000000000110000000000000000 13. Test 00000000000001110000000000000000 14. Stop 10101000000000100000000000000000 15. -21 to c 00000000000001110000000000000000 16. Stop 11010000000000000000000000000000 17. 11 01011000000000000000000000000000 18. 26</lang>
Stata
<lang stata>function caesar(s, k) { u = ascii(s) i = selectindex(u:>=65 :& u:<=90) if (length(i)>0) u[i] = mod(u[i]:+(k-65), 26):+65 i = selectindex(u:>=97 :& u:<=122) if (length(i)>0) u[i] = mod(u[i]:+(k-97), 26):+97 return(char(u)) }
caesar("layout", 20)
fusion</lang>
Swift
<lang swift> func usage(_ e:String) {
print("error: \(e)")
print("./caeser -e 19 a-secret-string")
print("./caeser -d 19 tskxvjxlskljafz")
}
func charIsValid(_ c:Character) -> Bool {
return c.isASCII && ( c.isLowercase || 45 == c.asciiValue ) // '-' = 45
}
func charRotate(_ c:Character, _ by:Int) -> Character {
var cv:UInt8! = c.asciiValue
if 45 == cv { cv = 96 } // if '-', set it to 'a'-1
cv += UInt8(by)
if 122 < cv { cv -= 27 } // if larget than 'z', reduce by 27
if 96 == cv { cv = 45 } // restore '-'
return Character(UnicodeScalar(cv))
}
func caesar(_ enc:Bool, _ key:Int, _ word:String) -> String {
let r = enc ? key : 27 - key
func charRotateWithKey(_ c:Character) -> Character {
return charRotate(c,r)
}
return String(word.map(charRotateWithKey))
}
func main() {
var encrypt = true
if 4 != CommandLine.arguments.count {
return usage("caesar expects exactly three arguments")
}
switch ( CommandLine.arguments[1] ) {
case "-e":
encrypt = true
case "-d":
encrypt = false
default:
return usage("first argument must be -e (encrypt) or -d (decrypt)")
}
guard let key = Int(CommandLine.arguments[2]) else {
return usage("second argument not a number (must be in range 0-26)")
}
if key < 0 || 26 < key {
return usage("second argument not in range 0-26")
}
if !CommandLine.arguments[3].allSatisfy(charIsValid) {
return usage("third argument must only be lowercase ascii characters, or -")
}
let ans = caesar(encrypt,key,CommandLine.arguments[3])
print("\(ans)")
}
func test() {
if ( Character("a") != charRotate(Character("a"),0) ) {
print("Test Fail 1")
}
if ( Character("-") != charRotate(Character("-"),0) ) {
print("Test Fail 2")
}
if ( Character("-") != charRotate(Character("z"),1) ) {
print("Test Fail 3")
}
if ( Character("z") != charRotate(Character("-"),26)) {
print("Test Fail 4")
}
if ( "ihgmkzma" != caesar(true,8,"a-zecret") ) {
print("Test Fail 5")
}
if ( "a-zecret" != caesar(false,8,"ihgmkzma") ) {
print("Test Fail 6")
}
}
test() main() </lang>
Tcl
<lang tcl>package require Tcl 8.6; # Or TclOO package for 8.5
oo::class create Caesar {
variable encryptMap decryptMap
constructor shift {
for {set i 0} {$i < 26} {incr i} { # Play fast and loose with string/list duality for shorter code append encryptMap [format "%c %c %c %c " \ [expr {$i+65}] [expr {($i+$shift)%26+65}] \ [expr {$i+97}] [expr {($i+$shift)%26+97}]] append decryptMap [format "%c %c %c %c " \ [expr {$i+65}] [expr {($i-$shift)%26+65}] \ [expr {$i+97}] [expr {($i-$shift)%26+97}]] }
}
method encrypt text {
string map $encryptMap $text
}
method decrypt text {
string map $decryptMap $text
}
}</lang> Demonstrating: <lang tcl>set caesar [Caesar new 3] set txt "The five boxing wizards jump quickly." set enc [$caesar encrypt $txt] set dec [$caesar decrypt $enc] puts "Original message = $txt" puts "Encrypted message = $enc" puts "Decrypted message = $dec"</lang>
- Output:
Original message = The five boxing wizards jump quickly. Encrypted message = Wkh ilyh eralqj zlcdugv mxps txlfnob. Decrypted message = The five boxing wizards jump quickly.
TUSCRIPT
<lang tuscript>$$ MODE TUSCRIPT text="THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG" PRINT "text orginal ",text
abc="ABCDEFGHIJKLMNOPQRSTUVWXYZ",key=3,caesarskey=key+1 secretbeg=EXTRACT (abc,#caesarskey,0) secretend=EXTRACT (abc,0,#caesarskey) secretabc=CONCAT (secretbeg,secretend)
abc=STRINGS (abc,":</:"),secretabc=STRINGS (secretabc,":</:") abc=SPLIT (abc), secretabc=SPLIT (secretabc) abc2secret=JOIN(abc," ",secretabc),secret2abc=JOIN(secretabc," ",abc)
BUILD X_TABLE abc2secret=* DATA {abc2secret}
BUILD X_TABLE secret2abc=* DATA {secret2abc}
ENCODED = EXCHANGE (text,abc2secret) PRINT "text encoded ",encoded
DECODED = EXCHANGE (encoded,secret2abc) PRINT "encoded decoded ",decoded</lang>
- Output:
text orginal THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG text encoded WKH TXLFN EURZQ IRA MXPSV RYHU WKH ODCB GRJ encoded decoded THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG
TXR
The strategy here, one of many possible ones, is to build, at run time,the arguments to be passed to deffilter to construct a pair of filters enc and dec for encoding and decoding. Filters are specified as tuples of strings.
<lang txr>@(next :args)
@(cases)
@{key /[0-9]+/}
@text
@(or)
@ (throw error "specify <key-num> <text>")
@(end)
@(do
(defvar k (int-str key 10)))
@(bind enc-dec
@(collect-each ((i (range 0 25)))
(let* ((p (tostringp (+ #\a i)))
(e (tostringp (+ #\a (mod (+ i k) 26))))
(P (upcase-str p))
(E (upcase-str e)))
^(((,p ,e) (,P ,E))
((,e ,p) (,E ,P))))))
@(deffilter enc . @(mappend (fun first) enc-dec)) @(deffilter dec . @(mappend (fun second) enc-dec)) @(output) encoded: @{text :filter enc} decoded: @{text :filter dec} @(end)</lang>
- Output:
$ ./txr caesar.txr 12 'Hello, world!' encoded: Tqxxa, iadxp! decoded: Vszzc, kcfzr! $ ./txr caesar.txr 12 'Vszzc, kcfzr!' encoded: Hello, world! decoded: Jgnnq, yqtnf!
TypeScript
<lang javascript>function replace(input: string, key: number) : string { return input.replace(/([a-z])/g, ($1) => String.fromCharCode(($1.charCodeAt(0) + key + 26 - 97) % 26 + 97) ).replace(/([A-Z])/g, ($1) => String.fromCharCode(($1.charCodeAt(0) + key + 26 - 65) % 26 + 65)); }
// test var str = 'The five boxing wizards jump quickly'; var encoded = replace(str, 3); var decoded = replace(encoded, -3);
console.log('Enciphered: ' + encoded); console.log('Deciphered: ' + decoded);</lang>
UNIX Shell
I added a tr function to make this "pure" bash. In practice, you'd remove that function and use the external tr utility. <lang bash>caesar() {
local OPTIND
local encrypt n=0
while getopts :edn: option; do
case $option in
e) encrypt=true ;;
d) encrypt=false ;;
n) n=$OPTARG ;;
:) echo "error: missing argument for -$OPTARG" >&2
return 1 ;;
?) echo "error: unknown option -$OPTARG" >&2
return 1 ;;
esac
done
shift $((OPTIND-1))
if -z $encrypt ; then
echo "error: specify one of -e or -d" >&2
return 1
fi
local upper=ABCDEFGHIJKLMNOPQRSTUVWXYZ
local lower=abcdefghijklmnopqrstuvwxyz
if $encrypt; then
tr "$upper$lower" "${upper:n}${upper:0:n}${lower:n}${lower:0:n}" <<< "$1"
else
tr "${upper:n}${upper:0:n}${lower:n}${lower:0:n}" "$upper$lower" <<< "$1"
fi
}
tr() {
local -A charmap
local i trans line char
for ((i=0; i<${#1}; i++)); do
charmap[${1:i:1}]=${2:i:1}
done
while IFS= read -r line; do
trans=""
for ((i=0; i<${#line}; i++)); do
char=${line:i:1}
if [[ -n ${charmap[$char]} ]]; then
trans+=${charmap[$char]}
else
trans+=$char
fi
done
echo "$trans"
done
}
txt="The five boxing wizards jump quickly." enc=$(caesar -e -n 5 "$txt") dec=$(caesar -d -n 5 "$enc")
echo "original: $txt" echo "encrypted: $enc" echo "decrypted: $dec"</lang>
- Output:
original: The five boxing wizards jump quickly. encrypted: Ymj knaj gtcnsl bnefwix ozru vznhpqd. decrypted: The five boxing wizards jump quickly.
Ursa
<lang ursa>decl string mode while (not (or (= mode "encode") (= mode "decode"))) out "encode/decode: " console set mode (lower (in string console)) end while
decl string message out "message: " console set message (upper (in string console))
decl int key out "key: " console set key (in int console) if (or (> key 26) (< key 0)) out endl "invalid key" endl console stop end if
if (= mode "decode") set key (int (- 26 key)) end if
for (decl int i) (< i (size message)) (inc i) if (and (> (ord message) 64) (< (ord message) 91)) out (chr (int (+ (mod (int (+ (- (ord message) 65) key)) 26) 65))) console end if end for out endl console</lang>
Ursala
The reification operator (-:) generates efficient code for applications like this given a table of inputs and outputs, which is obtained in this case by zipping the alphabet with itself rolled the right number of times, done separately for the upper and lower case letters and then combined.
<lang Ursala>#import std
- import nat
enc "n" = * -:~&@T ^p(rep"n" ~&zyC,~&)~~K30K31X letters # encryption function dec "n" = * -:~&@T ^p(~&,rep"n" ~&zyC)~~K30K31X letters # decryption function
plaintext = 'the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY'
- show+ # exhaustive test
test = ("n". <.enc"n",dec"n"+ enc"n"> plaintext)*= nrange/1 25</lang>
- Output:
uif gjwf cpyjoh xjabset kvnq rvjdlmz UIF GJWF CPYJOH XJABSET KVNQ RVJDLMZ the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY vjg hkxg dqzkpi ykbctfu lwor swkemna VJG HKXG DQZKPI YKBCTFU LWOR SWKEMNA the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY wkh ilyh eralqj zlcdugv mxps txlfnob WKH ILYH ERALQJ ZLCDUGV MXPS TXLFNOB the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY xli jmzi fsbmrk amdevhw nyqt uymgopc XLI JMZI FSBMRK AMDEVHW NYQT UYMGOPC the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY ymj knaj gtcnsl bnefwix ozru vznhpqd YMJ KNAJ GTCNSL BNEFWIX OZRU VZNHPQD the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY znk lobk hudotm cofgxjy pasv waoiqre ZNK LOBK HUDOTM COFGXJY PASV WAOIQRE the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY aol mpcl ivepun dpghykz qbtw xbpjrsf AOL MPCL IVEPUN DPGHYKZ QBTW XBPJRSF the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY bpm nqdm jwfqvo eqhizla rcux ycqkstg BPM NQDM JWFQVO EQHIZLA RCUX YCQKSTG the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY cqn oren kxgrwp frijamb sdvy zdrltuh CQN OREN KXGRWP FRIJAMB SDVY ZDRLTUH the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY dro psfo lyhsxq gsjkbnc tewz aesmuvi DRO PSFO LYHSXQ GSJKBNC TEWZ AESMUVI the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY esp qtgp mzityr htklcod ufxa bftnvwj ESP QTGP MZITYR HTKLCOD UFXA BFTNVWJ the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY ftq ruhq najuzs iulmdpe vgyb cguowxk FTQ RUHQ NAJUZS IULMDPE VGYB CGUOWXK the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY gur svir obkvat jvmneqf whzc dhvpxyl GUR SVIR OBKVAT JVMNEQF WHZC DHVPXYL the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY hvs twjs pclwbu kwnofrg xiad eiwqyzm HVS TWJS PCLWBU KWNOFRG XIAD EIWQYZM the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY iwt uxkt qdmxcv lxopgsh yjbe fjxrzan IWT UXKT QDMXCV LXOPGSH YJBE FJXRZAN the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY jxu vylu renydw mypqhti zkcf gkysabo JXU VYLU RENYDW MYPQHTI ZKCF GKYSABO the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY kyv wzmv sfozex nzqriuj aldg hlztbcp KYV WZMV SFOZEX NZQRIUJ ALDG HLZTBCP the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY lzw xanw tgpafy oarsjvk bmeh imaucdq LZW XANW TGPAFY OARSJVK BMEH IMAUCDQ the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY max ybox uhqbgz pbstkwl cnfi jnbvder MAX YBOX UHQBGZ PBSTKWL CNFI JNBVDER the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY nby zcpy vircha qctulxm dogj kocwefs NBY ZCPY VIRCHA QCTULXM DOGJ KOCWEFS the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY ocz adqz wjsdib rduvmyn ephk lpdxfgt OCZ ADQZ WJSDIB RDUVMYN EPHK LPDXFGT the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY pda bera xktejc sevwnzo fqil mqeyghu PDA BERA XKTEJC SEVWNZO FQIL MQEYGHU the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY qeb cfsb ylufkd tfwxoap grjm nrfzhiv QEB CFSB YLUFKD TFWXOAP GRJM NRFZHIV the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY rfc dgtc zmvgle ugxypbq hskn osgaijw RFC DGTC ZMVGLE UGXYPBQ HSKN OSGAIJW the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY sgd ehud anwhmf vhyzqcr itlo pthbjkx SGD EHUD ANWHMF VHYZQCR ITLO PTHBJKX the five boxing wizards jump quickly THE FIVE BOXING WIZARDS JUMP QUICKLY
Vala
This is a port of the C# code present in this page. <lang Vala>static void println(string str) {
stdout.printf("%s\r\n", str);
}
static unichar encrypt_char(unichar ch, int code) {
if (!ch.isalpha()) return ch;
unichar offset = ch.isupper() ? 'A' : 'a'; return (unichar)((ch + code - offset) % 26 + offset);
}
static string encrypt(string input, int code) {
var builder = new StringBuilder();
unichar c;
for (int i = 0; input.get_next_char(ref i, out c);) {
builder.append_unichar(encrypt_char(c, code));
}
return builder.str;
}
static string decrypt(string input, int code) {
return encrypt(input, 26 - code);
}
const string test_case = "The quick brown fox jumped over the lazy dog";
void main() {
println(test_case); println(encrypt(test_case, -1)); println(decrypt(encrypt(test_case, -1), -1));
}</lang>
- Output:
The quick brown fox jumped over the lazy dog Sgd pthbj aqnvm enw itlodc nudq sgd kvyx cnf The quick brown fox jumped over the lwzy dog
VBA
<lang vb> Option Explicit
Sub Main_Caesar() Dim ch As String
ch = Caesar_Cipher("CAESAR: Who is it in the press that calls on me? I hear a tongue, shriller than all the music, Cry 'Caesar!' Speak; Caesar is turn'd to hear.", 14)
Debug.Print ch
Debug.Print Caesar_Cipher(ch, -14)
End Sub
Function Caesar_Cipher(sText As String, lngNumber As Long) As String Dim Tbl, strGlob As String, strTemp As String, i As Long, bytAscii As Byte
Const MAJ As String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
Const NB_LETTERS As Byte = 26
Const DIFFASCIIMAJ As Byte = 65 - NB_LETTERS
Const DIFFASCIIMIN As Byte = 97 - NB_LETTERS
strTemp = sText
If lngNumber < NB_LETTERS And lngNumber > NB_LETTERS * -1 Then
strGlob = String(NB_LETTERS * 4, " ")
LSet strGlob = MAJ & MAJ & MAJ
Tbl = Split(StrConv(strGlob, vbUnicode), Chr(0))
For i = 1 To Len(strTemp)
If Mid(strTemp, i, 1) Like "[a-zA-Z]" Then
bytAscii = Asc(Mid(strTemp, i, 1))
If Mid(strTemp, i, 1) = Tbl(bytAscii - DIFFASCIIMAJ) Then
Mid(strTemp, i) = Tbl(bytAscii - DIFFASCIIMAJ + lngNumber)
Else
Mid(strTemp, i) = LCase(Tbl(bytAscii - DIFFASCIIMIN + lngNumber))
End If
End If
Next i
End If
Caesar_Cipher = strTemp
End Function </lang>
- Output:
QOSGOF: Kvc wg wh wb hvs dfsgg hvoh qozzg cb as? W vsof o hcbuis, gvfwzzsf hvob ozz hvs aigwq, Qfm 'Qosgof!' Gdsoy; Qosgof wg hifb'r hc vsof. CAESAR: Who is it in the press that calls on me? I hear a tongue, shriller than all the music, Cry 'Caesar!' Speak; Caesar is turn'd to hear.
VBScript
Note that a left rotation has an equivalent right rotation so all rotations are converted to the equivalent right rotation prior to translation. <lang vb> str = "IT WAS THE BEST OF TIMES, IT WAS THE WORST OF TIMES."
Wscript.Echo str Wscript.Echo Rotate(str,5) Wscript.Echo Rotate(Rotate(str,5),-5)
'Rotate (Caesar encrypt/decrypt) test <numpos> positions. ' numpos < 0 - rotate left ' numpos > 0 - rotate right 'Left rotation is converted to equivalent right rotation
Function Rotate (text, numpos)
dim dic: set dic = CreateObject("Scripting.Dictionary") dim ltr: ltr = Split("A B C D E F G H I J K L M N O P Q R S T U V W X Y Z") dim rot: rot = (26 + numpos Mod 26) Mod 26 'convert all to right rotation dim ch dim i
for i = 0 to ubound(ltr) dic(ltr(i)) = ltr((rot+i) Mod 26) next
Rotate = ""
for i = 1 to Len(text) ch = Mid(text,i,1) if dic.Exists(ch) Then Rotate = Rotate & dic(ch) else Rotate = Rotate & ch end if next
End Function </lang>
- Output:
D:\script>Caesar.vbs IT WAS THE BEST OF TIMES, IT WAS THE WORST OF TIMES. NY BFX YMJ GJXY TK YNRJX, NY BFX YMJ BTWXY TK YNRJX. IT WAS THE BEST OF TIMES, IT WAS THE WORST OF TIMES.
Vedit macro language
This implementation ciphers/deciphers a highlighted block of text in-place in current edit buffer. <lang vedit>#10 = Get_Num("Enter the key: positive to cipher, negative to de-cipher: ", STATLINE)
Goto_Pos(Block_Begin) while(Cur_Pos < Block_End) {
#11 = Cur_Char & 0x60 + 1
if (Cur_Char >= 'A') {
Ins_Char((Cur_Char - #11 + 26 + #10) % 26 + #11, OVERWRITE)
} else {
Char(1)
}
}</lang>
- Output:
with key 13
Original text: Quick brown Fox jumps over the lazy Dog. Encrypted text: Dhvpx oebja Sbk whzcf bire gur ynml Qbt. Decrypted text: Quick brown Fox jumps over the lazy Dog.
Visual Basic .NET
<lang vbnet>Module Module1
Function Encrypt(ch As Char, code As Integer) As Char
If Not Char.IsLetter(ch) Then
Return ch
End If
Dim offset = AscW(If(Char.IsUpper(ch), "A"c, "a"c))
Dim test = (AscW(ch) + code - offset) Mod 26 + offset
Return ChrW(test)
End Function
Function Encrypt(input As String, code As Integer) As String
Return New String(input.Select(Function(ch) Encrypt(ch, code)).ToArray())
End Function
Function Decrypt(input As String, code As Integer) As String
Return Encrypt(input, 26 - code)
End Function
Sub Main()
Dim str = "Pack my box with five dozen liquor jugs."
Console.WriteLine(str)
str = Encrypt(str, 5)
Console.WriteLine("Encrypted: {0}", str)
str = Decrypt(str, 5)
Console.WriteLine("Decrypted: {0}", str)
End Sub
End Module</lang>
- Output:
Pack my box with five dozen liquor jugs. Encrypted: Ufhp rd gtc bnym knaj itejs qnvztw ozlx. Decrypted: Pack my box with five dozen liquor jugs.
Wortel
<lang wortel>@let {
; this function only replaces letters and keeps case
ceasar &[s n] !!s.replace &"[a-z]"gi &[x] [
@vars {
t x.charCodeAt.
l ?{
&& > t 96 < t 123 97
&& > t 64 < t 91 65
0
}
}
!String.fromCharCode ?{
l +l ~% 26 -+ n t l
t
}
]
!!ceasar "abc $%^ ABC" 10
}</lang> Returns:
"klm $%^ KLM"
Wren
<lang ecmascript>class Caesar {
static encrypt(s, key) {
var offset = key % 26
if (offset == 0) return s
var chars = List.filled(s.count, 0)
for (i in 0...s.count) {
var c = s[i].bytes[0]
var d = c
if (c >= 65 && c <= 90) { // 'A' to 'Z'
d = c + offset
if (d > 90) d = d - 26
} else if (c >= 97 && c <= 122) { // 'a' to 'z'
d = c + offset
if (d > 122) d = d - 26
}
chars[i] = d
}
return chars.reduce("") { |acc, c| acc + String.fromByte(c) }
}
static decrypt(s, key) { encrypt(s, 26 - key) }
}
var encoded = Caesar.encrypt("Bright vixens jump; dozy fowl quack.", 8) System.print(encoded) System.print(Caesar.decrypt(encoded, 8))</lang>
- Output:
Jzqopb dqfmva rcux; lwhg nwet yciks. Bright vixens jump; dozy fowl quack.
X86 Assembly
<lang asm> # Author: Ettore Forigo - Hexwell
.intel_syntax noprefix
.text .globl main main: .PROLOGUE:
push rbp mov rbp, rsp sub rsp, 32 mov QWORD PTR [rbp-32], rsi # argv
.BODY:
mov BYTE PTR [rbp-1], 0 # shift = 0
.I_LOOP_INIT:
mov BYTE PTR [rbp-2], 0 # i = 0
jmp .I_LOOP_CONDITION # I_LOOP_CONDITION
.I_LOOP_BODY:
movzx edx, BYTE PTR[rbp-1] # shift
mov eax, edx # shift
sal eax, 2 # shift << 2 == i * 4
add eax, edx # shift * 4 + shift = shift * 5
add eax, eax # shift * 5 + shift * 5 = shift * 10
mov ecx, eax # shift * 10
mov rax, QWORD PTR [rbp-32] # argv
add rax, 8 # argv + 1
mov rdx, QWORD PTR [rax] # argv[1]
movzx eax, BYTE PTR [rbp-2] # i
add rax, rdx # argv[1] + i
movzx eax, BYTE PTR [rax] # argv[1][i]
add eax, ecx # shift * 10 + argv[1][i]
sub eax, 48 # shift * 10 + argv[1][i] - '0'
mov BYTE PTR [rbp-1], al # shift = shift * 10 + argv[1][i] - '0'
.I_LOOP_INCREMENT:
movzx eax, BYTE PTR [rbp-2] # i
add eax, 1 # i + 1
mov BYTE PTR [rbp-2], al # i++
.I_LOOP_CONDITION:
mov rax, QWORD PTR [rbp-32] # argv
add rax, 8 # argv + 1
mov rax, QWORD PTR [rax] # argv[1]
movzx edx, BYTE PTR [rbp-2] # i
add rax, rdx # argv[1] + i
movzx rax, BYTE PTR [rax] # argv[1][i]
test al, al # argv[1][i]?
jne .I_LOOP_BODY # I_LOOP_BODY
.CAESAR_LOOP_INIT:
mov BYTE PTR [rbp-2], 0 # i = 0
jmp .CAESAR_LOOP_CONDITION # CAESAR_LOOP_CONDITION
.CAESAR_LOOP_BODY:
mov rax, QWORD PTR [rbp-32] # argv
add rax, 16 # argv + 2
mov rdx, QWORD PTR [rax] # argv[2]
movzx eax, BYTE PTR [rbp-2] # i
add rax, rdx # argv[2] + i
mov rbx, rax # argv[2] + i
movzx eax, BYTE PTR [rax] # argv[2][i]
cmp al, 32 # argv[2][i] == ' '
je .CAESAR_LOOP_INCREMENT # CAESAR_LOOP_INCREMENT
movzx edx, BYTE PTR [rbx] # argv[2][i]
mov ecx, edx # argv[2][i]
movzx edx, BYTE PTR [rbp-1] # shift
add edx, ecx # argv[2][i] + shift
sub edx, 97 # argv[2][i] + shift - 'a'
mov BYTE PTR [rbx], dl # argv[2][i] = argv[2][i] + shift - 'a'
movzx eax, BYTE PTR [rbx] # argv[2][i]
cmp al, 25 # argv[2][i] <=> 25
jle .CAESAR_RESTORE_ASCII # <= CAESAR_RESTORE_ASCII
movzx edx, BYTE PTR [rbx] # argv[2][i]
sub edx, 26 # argv[2][i] - 26
mov BYTE PTR [rbx], dl # argv[2][i] = argv[2][i] - 26
.CAESAR_RESTORE_ASCII:
movzx edx, BYTE PTR [rbx] # argv[2][i]
add edx, 97 # argv[2][i] + 'a'
mov BYTE PTR [rbx], dl # argv[2][i] = argv[2][i] + 'a'
.CAESAR_LOOP_INCREMENT:
movzx eax, BYTE PTR [rbp-2] # i
add eax, 1 # i + 1
mov BYTE PTR [rbp-2], al # i++
.CAESAR_LOOP_CONDITION:
mov rax, QWORD PTR [rbp-32] # argv
add rax, 16 # argv + 2
mov rdx, QWORD PTR [rax] # argv[2]
movzx eax, BYTE PTR [rbp-2] # i
add rax, rdx # argv[2] + i
movzx eax, BYTE PTR [rax] # argv[2][i]
test al, al # argv[2][i]?
jne .CAESAR_LOOP_BODY # CAESAR_LOOP_BODY
mov rax, QWORD PTR [rbp-32] # argv add rax, 16 # argv + 2 mov rax, QWORD PTR [rax] # argv[2] mov rdi, rax # argv[2] call puts # puts(argv[2])
.RETURN:
mov eax, 0 # 0 leave ret # return 0</lang>
Usage: <lang bash>$ gcc caesar.S -o caesar $ ./caesar 10 abc klm $ ./caesar 16 klm abc</lang>
XBasic
<lang xbasic> PROGRAM "caesarcipher" VERSION "0.0001"
DECLARE FUNCTION Entry() INTERNAL FUNCTION Encrypt$(p$, key%%) INTERNAL FUNCTION Decrypt$(p$, key%%)
FUNCTION Entry()
txt$ = "The five boxing wizards jump quickly" key%% = 3 PRINT "Original: "; txt$ enc$ = Encrypt$(txt$, key%%) PRINT "Encrypted: "; enc$ PRINT "Decrypted: "; Decrypt$(enc$, key%%)
END FUNCTION
FUNCTION Encrypt$(p$, key%%)
e$ = p$ ' In order to avoid iterative concatenations
FOR i = 0 TO LEN(p$) - 1
t@@ = p${i} ' or (slower) t@@ = ASC(p$, i + 1)
SELECT CASE TRUE
CASE (t@@ >= 'A') AND (t@@ <= 'Z'):
t@@ = t@@ + key@@
IF t&& > 'Z' THEN
t@@ = t@@ - 26
END IF
CASE (t@@ >= 'a') AND (t@@ <= 'z'):
t@@ = t@@ + key%%
IF t@@ > 'z' THEN
t@@ = t@@ - 26
END IF
END SELECT
e${i} = t@@
NEXT i
END FUNCTION e$
FUNCTION Decrypt$(p$, key%%)
e$ = p$ ' In order to avoid iterative concatenations
FOR i = 0 TO LEN(p$) - 1
t@@ = p${i} ' or (slower) t@@ = ASC(p$, i + 1)
SELECT CASE TRUE
CASE (t@@ >= 'A') AND (t@@ <= 'Z'):
t@@ = t@@ - key%%
IF t@@ < 'A' THEN
t@@ = t@@ + 26
END IF
CASE (t@@ >= 'a') AND (t@@ <= 'z'):
t@@ = t@@ - key%%
IF t@@ < 'a' THEN
t@@ = t@@ + 26
END IF
END SELECT
e${i} = t@@
NEXT i
END FUNCTION e$ END PROGRAM </lang>
- Output:
Original: The five boxing wizards jump quickly Encrypted: Wkh ilyh eralqj zlcdugv mxps txlfnob Decrypted: The five boxing wizards jump quickly
XBS
<lang xbs>set letters="ABCDEFGHIJKLMNOPQRSTUVWXYZ"::split();
func caesar(text,shift:number=1){ set res:string=""; for(i=0;?text-1;1){ set t=text::at(i); set n=(letters::find(t::upper())+shift)%?letters; while(n<0){ n=?letters+n; } set l=letters[n]; (t::upper()==t)|=>l=l::lower() res+=l; } send res; }
func decode(text,shift:number=1){ set res:string=""; for(i=0;?text-1;1){ set t=text::at(i); set n=(letters::find(t::upper())-shift)%?letters; while(n<0){ n=?letters+n; } set l=letters[n]; (t::upper()==t)|=>l=l::lower() res+=l; } send res; }
set e=caesar("Hi",20); set d=decode(e,20);
log(e); log(d);</lang>
- Output:
Bc Hi
XLISP
<lang lisp>(defun caesar-encode (text key)
(defun encode (ascii-code)
(defun rotate (character alphabet)
(define code (+ character key))
(cond
((> code (+ alphabet 25)) (- code 26))
((< code alphabet) (+ code 26))
(t code)))
(cond
((and (>= ascii-code 65) (<= ascii-code 90)) (rotate ascii-code 65))
((and (>= ascii-code 97) (<= ascii-code 122)) (rotate ascii-code 97))
(t ascii-code)))
(list->string (mapcar integer->char (mapcar encode (mapcar char->integer (string->list text))))))
(defun caesar-decode (text key)
(caesar-encode text (- 26 key)))</lang>
Test it in a REPL: <lang lisp>[1] (define caesar-test (caesar-encode "CAESAR: Who is it in the press that calls on me? I hear a tongue, shriller than all the music, Cry 'Caesar!' Speak; Caesar is turn'd to hear." 14))
CAESAR-TEST [2] caesar-test
"QOSGOF: Kvc wg wh wb hvs dfsgg hvoh qozzg cb as? W vsof o hcbuis, gvfwzzsf hvob ozz hvs aigwq, Qfm 'Qosgof!' Gdsoy; Qosgof wg hifb'r hc vsof." [3] (caesar-decode caesar-test 14)
"CAESAR: Who is it in the press that calls on me? I hear a tongue, shriller than all the music, Cry 'Caesar!' Speak; Caesar is turn'd to hear."</lang>
XPL0
To decrypt a message use the negative value of the encrypting key. Usage: caesar key <infile.txt >outfile.xxx
<lang XPL0>code ChIn=7, ChOut=8, IntIn=10; int Key, C; [Key:= IntIn(8); repeat C:= ChIn(1);
if C>=^a & C<=^z then C:= C-$20;
if C>=^A & C<=^Z then
[C:= C+Key;
if C>^Z then C:= C-26
else if C<^A then C:= C+26;
];
ChOut(0, C);
until C=$1A; \EOF ]</lang>
Example outfile.xxx:
SDFN PB ERA ZLWK ILYH GRCHQ OLTXRU MXJV.
Yabasic
<lang Yabasic> REM *** By changing the key and pattern, an encryption system that is difficult to break can be achieved. ***
text$ = "You are encouraged to solve this task according to the task description, using any language you may know." key$ = "desoxirribonucleic acid" // With a single character you get a Caesar encryption. With more characters the key is much more difficult to discover. CIPHER = 1 : DECIPHER = -1
print text$ : print encrypted$ = criptex$(text$, key$, CIPHER) a = open("cryptedText.txt", "w") : if a then print #a encrypted$ : close #a end if print encrypted$ : print print criptex$(encrypted$, key$, DECIPHER)
sub criptex$(text$, key$, mode) local i, k, delta, longtext, longPattern, longkey, pattern$, res$
pattern$ = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890 .,;:()-"
longPattern = len(pattern$) longtext = len(text$) longkey = len(key$)
for i = 1 to longtext k = k + 1 : if k > longkey k = 1 delta = instr(pattern$, mid$(text$, i, 1)) delta = delta + (mode * instr(pattern$, mid$(key$, k, 1))) if delta > longPattern then delta = delta - longPattern elseif delta < 1 then delta = longPattern + delta end if res$ = res$ + mid$(pattern$, delta, 1) next i
return res$ end sub</lang>
- Output:
You are encouraged to solve this task according to the task description, using any language you may know. 3tNhyAwknprCPumlng4urbwsqOtqCzAB,IoNneflfhsgrrk(MDqCzwbvpGF;pjBfkjsCmssnhSBAFp,pBT;xfwjnbjn:CtNhKjQktpDKo You are encouraged to solve this task according to the task description, using any language you may know.
zkl
<lang zkl>fcn caesarCodec(str,n,encode=True){
var [const] letters=["a".."z"].chain(["A".."Z"]).pump(String); // static if(not encode) n=26 - n; m,sz := n + 26, 26 - n; ltrs:=String(letters[n,sz],letters[0,n],letters[m,sz],letters[26,n]); str.translate(letters,ltrs)
}</lang> <lang zkl>text:="The five boxing wizards jump quickly"; N:=3; code:=caesarCodec(text,N); println("text = ",text); println("encoded(%d) = %s".fmt(N,code)); println("decoded = ",caesarCodec(code,N,False));</lang>
- Output:
text = The five boxing wizards jump quickly encoded(3) = Wkh ilyh eralqj zlcdugv mxps txlfnob decoded = The five boxing wizards jump quickly
zonnon
<lang zonnon> module Caesar; const size = 25;
type Operation = (code,decode);
procedure C_D(s:string;k:integer;op: Operation): string; var i,key: integer; resp: string; n,c: char; begin resp := ""; if op = Operation.decode then key := k else key := (26 - k) end; for i := 0 to len(s) - 1 do c := cap(s[i]); if (c >= 'A') & (c <= 'Z') then resp := resp + string(char(integer('A') + ((integer(c) - integer('A') + key )) mod 26)); else resp := resp + string(c) end; end; return resp end C_D;
procedure {public} Cipher(s:string;k:integer):string; var i: integer; resp: string; n,c: char; begin return C_D(s,k,Operation.code) end Cipher;
procedure {public} Decipher(s:string;k:integer):string; var i: integer; resp: string; n,c: char; begin return C_D(s,k,Operation.decode) end Decipher;
var txt,cipher,decipher: string;
begin txt := "HI";cipher := Caesar.Cipher(txt,2);decipher := Caesar.Decipher(cipher,2); writeln(txt," -c-> ",cipher," -d-> ",decipher); txt := "ZA";cipher := Caesar.Cipher(txt,2);decipher := Caesar.Decipher(cipher,2); writeln(txt," -c-> ",cipher," -d-> ",decipher); txt := "The five boxing wizards jump quickly"; cipher := Caesar.Cipher(txt,2);decipher := Caesar.Decipher(cipher,2); writeln(txt," -c-> ",cipher," -d-> ",decipher) end Caesar. </lang>
- Output:
HI -c-> FG -d-> HI ZA -c-> XY -d-> ZA The five boxing wizards jump quickly -c-> RFC DGTC ZMVGLE UGXYPBQ HSKN OSGAIJW -d-> THE FIVE BOXING WIZARDS JUMP QUICKLY
ZX Spectrum Basic
<lang zxbasic>10 LET t$="PACK MY BOX WITH FIVE DOZEN LIQUOR JUGS" 20 PRINT t$ 30 LET key=RND*25+1 40 LET k=key: GO SUB 1000: PRINT t$ 50 LET k=26-key: GO SUB 1000: PRINT t$ 60 STOP 1000 FOR i=1 TO LEN t$ 1010 LET c= CODE t$(i) 1020 IF c<65 OR c>90 THEN GO TO 1050 1030 LET c=c+k: IF c>90 THEN LET c=c-90+64 1040 LET t$(i)=CHR$ c 1050 NEXT i 1060 RETURN </lang>
<lang zxbasic>10 LET t$="Wonderful ZX Spectrum." 20 LET c$="a":REM more characters, more difficult for decript 30 LET CIFRA=1: LET DESCIFRA=-1 40 PRINT t$ 50 LET modo=CIFRA: GO SUB 1000 60 PRINT r$ 70 LET t$=r$: LET modo=DESCIFRA: GO SUB 1000 80 PRINT r$ 90 STOP 1000 REM Criptex 1010 LET p$="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890 .,;:()-" 1020 LET longPatron=LEN p$ 1030 LET longTexto=LEN t$ 1040 LET longClave=LEN c$ 1045 LET k=0: LET r$="" 1050 FOR i=1 TO longTexto 1060 LET k=k+1: IF k>longClave THEN LET k=1 1070 LET x$=t$(i) 1080 FOR j=1 TO longPatron 1090 IF x$=p$(j) THEN LET delta=j: GO TO 1110 1100 NEXT j 1110 LET x$=c$(k) 1120 FOR j=1 TO longPatron 1130 IF x$=p$(j) THEN LET delta=delta+modo*j: GO TO 1150 1140 NEXT j 1150 IF delta>longPatron THEN LET delta=delta-longPatron: GO TO 1170 1160 IF delta<1 THEN LET delta=longPatron+delta 1170 LET r$=r$+p$(delta) 1180 NEXT i 1190 RETURN </lang>