The ISAAC Cipher

From Rosetta Code
Task
The ISAAC Cipher
You are encouraged to solve this task according to the task description, using any language you may know.

ISAAC is a cryptographically secure pseudo-random number generator (CSPRNG) and stream cipher. It was developed by Bob Jenkins from 1993 (http://burtleburtle.net/bob/rand/isaac.html) and placed in the Public Domain. ISAAC is fast - especially when optimised - and portable to most architectures in nearly all programming and scripting languages. It is also simple and succinct, using as it does just two 256-word arrays for its state.

ISAAC stands for "Indirection, Shift, Accumulate, Add, and Count" which are the principal bitwise operations employed. To date - and that's after more than 20 years of existence - ISAAC has not been broken (unless GCHQ or NSA did it, but they wouldn't be telling). ISAAC thus deserves a lot more attention than it has hitherto received and it would be salutary to see it more universally implemented.


Task

Translate ISAAC's reference C or Pascal code into your language of choice.

The RNG should then be seeded with the string "this is my secret key" and finally the message "a Top Secret secret" should be encrypted on that key. Your program's output cipher-text will be a string of hexadecimal digits.

Optional: Include a decryption check by re-initializing ISAAC and performing the same encryption pass on the cipher-text.

Please use the C or Pascal as a reference guide to these operations.

Two encryption schemes are possible: (1) XOR (Vernam) or (2) Caesar-shift mod 95 (Vigenère). XOR is the simplest; C-shifting offers greater security.

You may choose either scheme, or both, but please specify which you used. Here are the alternative sample outputs for checking purposes:

Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1C0636190B1260233B35125F1E1D0E2F4C5422
MOD    : 734270227D36772A783B4F2A5F206266236978
XOR dcr: a Top Secret secret
MOD dcr: a Top Secret secret

No official seeding method for ISAAC has been published, but for this task we may as well just inject the bytes of our key into the randrsl array, padding with zeroes before mixing, like so:

// zeroise mm array
FOR i:= 0 TO 255 DO mm[i]:=0;
// check seed's highest array element
m := High(seed);
// inject the seed
FOR i:= 0 TO 255 DO BEGIN
	// in case seed[] has less than 256 elements.
	IF i>m THEN randrsl[i]:=0  
		ELSE randrsl[i]:=seed[i];
END;
// initialize ISAAC with seed
RandInit(true);

ISAAC can of course also be initialized with a single 32-bit unsigned integer in the manner of traditional RNGs, and indeed used as such for research and gaming purposes. But building a strong and simple ISAAC-based stream cipher - replacing the irreparably broken RC4 - is our goal here: ISAAC's intended purpose.

C[edit]

At the top is Bob Jenkins' reference code for ISAAC. Below and in main() is the task's complete solution for XOR and MOD.

 
/* Known to compile and work with tcc in win32 & gcc on Linux (with warnings)
------------------------------------------------------------------------------
readable.c: My random number generator, ISAAC.
(c) Bob Jenkins, March 1996, Public Domain
You may use this code in any way you wish, and it is free. No warrantee.
------------------------------------------------------------------------------
*/

#include <stdio.h>
#include <stddef.h>
#include <string.h>
#ifdef _MSC_VER
typedef unsigned __int32 uint32_t;
#else
#include <stdint.h>
#endif
 
/* a ub4 is an unsigned 4-byte quantity */
typedef uint32_t ub4;
 
/* external results */
ub4 randrsl[256], randcnt;
 
/* internal state */
static ub4 mm[256];
static ub4 aa=0, bb=0, cc=0;
 
void isaac()
{
register ub4 i,x,y;
 
cc = cc + 1; /* cc just gets incremented once per 256 results */
bb = bb + cc; /* then combined with bb */
 
for (i=0; i<256; ++i)
{
x = mm[i];
switch (i%4)
{
case 0: aa = aa^(aa<<13); break;
case 1: aa = aa^(aa>>6); break;
case 2: aa = aa^(aa<<2); break;
case 3: aa = aa^(aa>>16); break;
}
aa = mm[(i+128)%256] + aa;
mm[i] = y = mm[(x>>2)%256] + aa + bb;
randrsl[i] = bb = mm[(y>>10)%256] + x;
}
// not in original readable.c
randcnt = 0;
}
 
/* if (flag!=0), then use the contents of randrsl[] to initialize mm[]. */
#define mix(a,b,c,d,e,f,g,h) \
{ \
a^=b<<11; d+=a; b+=c; \
b^=c>>2; e+=b; c+=d; \
c^=d<<8; f+=c; d+=e; \
d^=e>>16; g+=d; e+=f; \
e^=f<<10; h+=e; f+=g; \
f^=g>>4; a+=f; g+=h; \
g^=h<<8; b+=g; h+=a; \
h^=a>>9; c+=h; a+=b; \
}

 
void randinit(int flag)
{
register int i;
ub4 a,b,c,d,e,f,g,h;
aa=bb=cc=0;
a=b=c=d=e=f=g=h=0x9e3779b9; /* the golden ratio */
 
for (i=0; i<4; ++i) /* scramble it */
{
mix(a,b,c,d,e,f,g,h);
}
 
for (i=0; i<256; i+=8) /* fill in mm[] with messy stuff */
{
if (flag) /* use all the information in the seed */
{
a+=randrsl[i ]; b+=randrsl[i+1]; c+=randrsl[i+2]; d+=randrsl[i+3];
e+=randrsl[i+4]; f+=randrsl[i+5]; g+=randrsl[i+6]; h+=randrsl[i+7];
}
mix(a,b,c,d,e,f,g,h);
mm[i ]=a; mm[i+1]=b; mm[i+2]=c; mm[i+3]=d;
mm[i+4]=e; mm[i+5]=f; mm[i+6]=g; mm[i+7]=h;
}
 
if (flag)
{ /* do a second pass to make all of the seed affect all of mm */
for (i=0; i<256; i+=8)
{
a+=mm[i ]; b+=mm[i+1]; c+=mm[i+2]; d+=mm[i+3];
e+=mm[i+4]; f+=mm[i+5]; g+=mm[i+6]; h+=mm[i+7];
mix(a,b,c,d,e,f,g,h);
mm[i ]=a; mm[i+1]=b; mm[i+2]=c; mm[i+3]=d;
mm[i+4]=e; mm[i+5]=f; mm[i+6]=g; mm[i+7]=h;
}
}
 
isaac(); /* fill in the first set of results */
randcnt=0; /* prepare to use the first set of results */
}
 
 
// Get a random 32-bit value 0..MAXINT
ub4 iRandom()
{
ub4 r = randrsl[randcnt];
++randcnt;
if (randcnt >255) {
isaac();
randcnt = 0;
}
return r;
}
 
 
// Get a random character in printable ASCII range
char iRandA()
{
return iRandom() % 95 + 32;
}
 
 
// Seed ISAAC with a string
void iSeed(char *seed, int flag)
{
register ub4 i,m;
for (i=0; i<256; i++) mm[i]=0;
m = strlen(seed);
for (i=0; i<256; i++)
{
// in case seed has less than 256 elements
if (i>m) randrsl[i]=0; else randrsl[i] = seed[i];
}
// initialize ISAAC with seed
randinit(flag);
}
 
 
// maximum length of message
#define MAXMSG 4096
#define MOD 95
#define START 32
// cipher modes for Caesar
enum ciphermode {
mEncipher, mDecipher, mNone
};
 
 
// XOR cipher on random stream. Output: ASCII string
char v[MAXMSG];
char* Vernam(char *msg)
{
register ub4 i,l;
l = strlen(msg);
// zeroise v
memset(v,'\0',l+1);
// XOR message
for (i=0; i<l; i++)
v[i] = iRandA() ^ msg[i];
return v;
}
 
 
// Caesar-shift a printable character
char Caesar(enum ciphermode m, char ch, char shift, char modulo, char start)
{
register int n;
if (m == mDecipher) shift = -shift;
n = (ch-start) + shift;
n = n % modulo;
if (n<0) n += modulo;
return start+n;
}
 
// Caesar-shift a string on a pseudo-random stream
char c[MAXMSG];
char* CaesarStr(enum ciphermode m, char *msg, char modulo, char start)
{
register ub4 i,l;
l = strlen(msg);
// zeroise c
memset(c,'\0',l+1);
// Caesar-shift message
for (i=0; i<l; i++)
c[i] = Caesar(m, msg[i], iRandA(), modulo, start);
return c;
}
 
 
int main()
{
register ub4 n,l;
// input: message and key
char *msg = "a Top Secret secret";
char *key = "this is my secret key";
// Vernam ciphertext & plaintext
char vctx[MAXMSG], vptx[MAXMSG];
// Caesar ciphertext & plaintext
char cctx[MAXMSG], cptx[MAXMSG];
l = strlen(msg);
// Encrypt: Vernam XOR
iSeed(key,1);
strcpy(vctx, Vernam(msg));
// Encrypt: Caesar
strcpy(cctx, CaesarStr(mEncipher, msg, MOD, START));
// Decrypt: Vernam XOR
iSeed(key,1);
strcpy(vptx, Vernam(vctx));
// Decrypt: Caesar
strcpy(cptx, CaesarStr(mDecipher,cctx, MOD, START));
// Program output
printf("Message: %s\n",msg);
printf("Key  : %s\n",key);
printf("XOR  : ");
// Output Vernam ciphertext as a string of hex digits
for (n=0; n<l; n++) printf("%02X",vctx[n]);
printf("\n");
// Output Vernam decrypted plaintext
printf("XOR dcr: %s\n",vptx);
// Caesar
printf("MOD  : ");
// Output Caesar ciphertext as a string of hex digits
for (n=0; n<l; n++) printf("%02X",cctx[n]);
printf("\n");
// Output Caesar decrypted plaintext
printf("MOD dcr: %s\n",cptx);
return 0;
}
 
Output:
Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1C0636190B1260233B35125F1E1D0E2F4C5422
XOR dcr: a Top Secret secret
MOD    : 734270227D36772A783B4F2A5F206266236978
MOD dcr: a Top Secret secret

C#[edit]

XOR with decryption check.

 
using System;
 
namespace cipher {
 
static class Cipher {
 
// external results
static uint[] randrsl = new uint[256];
static uint randcnt;
// internal state
static uint[] mm = new uint[256];
static uint aa=0, bb=0, cc=0;
 
 
static void isaac() {
uint i,x,y;
cc++; // cc just gets incremented once per 256 results
bb+=cc; // then combined with bb
 
for (i=0; i<=255; i++) {
x = mm[i];
switch (i & 3) {
case 0: aa = aa ^ (aa << 13); break;
case 1: aa = aa ^ (aa >> 6); break;
case 2: aa = aa ^ (aa << 2); break;
case 3: aa = aa ^ (aa >> 16); break;
}
aa = mm[(i+128) & 255] + aa;
y = mm[(x >> 2) & 255] + aa + bb;
mm[i] = y;
bb = mm[(y >> 10) & 255] + x;
randrsl[i]= bb;
}
}
 
 
// if (flag==TRUE), then use the contents of randrsl[] to initialize mm[].
static void mix(ref uint a, ref uint b, ref uint c, ref uint d, ref uint e, ref uint f, ref uint g, ref uint h) {
a = a ^ b << 11; d+=a; b+=c;
b = b ^ c >> 2; e+=b; c+=d;
c = c ^ d << 8; f+=c; d+=e;
d = d ^ e >> 16; g+=d; e+=f;
e = e ^ f << 10; h+=e; f+=g;
f = f ^ g >> 4; a+=f; g+=h;
g = g ^ h << 8; b+=g; h+=a;
h = h ^ a >> 9; c+=h; a+=b;
}
 
 
static void Init(bool flag) {
short i; uint a,b,c,d,e,f,g,h;
 
aa=0; bb=0; cc=0;
a=0x9e3779b9; b=a; c=a; d=a;
e=a; f=a; g=a; h=a;
 
for (i=0; i<=3; i++) // scramble it
mix(ref a,ref b,ref c,ref d,ref e,ref f,ref g,ref h);
 
i=0;
do { // fill in mm[] with messy stuff
if (flag) { // use all the information in the seed
a+=randrsl[i ]; b+=randrsl[i+1]; c+=randrsl[i+2]; d+=randrsl[i+3];
e+=randrsl[i+4]; f+=randrsl[i+5]; g+=randrsl[i+6]; h+=randrsl[i+7];
} // if flag
 
mix(ref a,ref b,ref c,ref d,ref e,ref f,ref g,ref h);
mm[i ]=a; mm[i+1]=b; mm[i+2]=c; mm[i+3]=d;
mm[i+4]=e; mm[i+5]=f; mm[i+6]=g; mm[i+7]=h;
i+=8;
}
while (i<255);
 
if (flag) {
// do a second pass to make all of the seed affect all of mm
i=0;
do {
a+=mm[i ]; b+=mm[i+1]; c+=mm[i+2]; d+=mm[i+3];
e+=mm[i+4]; f+=mm[i+5]; g+=mm[i+6]; h+=mm[i+7];
mix(ref a,ref b,ref c,ref d,ref e,ref f,ref g,ref h);
mm[i ]=a; mm[i+1]=b; mm[i+2]=c; mm[i+3]=d;
mm[i+4]=e; mm[i+5]=f; mm[i+6]=g; mm[i+7]=h;
i+=8;
}
while (i<255);
}
isaac(); // fill in the first set of results
randcnt=0; // prepare to use the first set of results
}
 
 
// Seed ISAAC with a string
static void Seed(string seed, bool flag) {
for (int i=0; i<256; i++) mm[i]=0;
for (int i=0; i<256; i++) randrsl[i]=0;
int m = seed.Length;
for (int i=0; i<m; i++) {
randrsl[i] = seed[i];
}
// initialize ISAAC with seed
Init(flag);
}
 
 
// Get a random 32-bit value
static uint Random() {
uint result = randrsl[randcnt];
randcnt++;
if (randcnt>255) {
isaac(); randcnt=0;
}
return result;
}
 
 
// Get a random character in printable ASCII range
static byte RandA() {
return (byte)(Random() % 95 + 32);
}
 
 
// XOR encrypt on random stream. Output: ASCII byte array
static byte[] Vernam(string msg)
{
int n,l;
byte[] v = new byte[msg.Length];
l = msg.Length;
// XOR message
for (n=0; n<l; n++) {
v[n] = (byte) (RandA() ^ (byte)msg[n]);
}
return v;
}
 
 
public static void Main() {
string msg = "a Top Secret secret";
string key = "this is my secret key";
byte[] xctx= new byte[msg.Length];
byte[] xptx= new byte[msg.Length];
string xtcx= "*******************";
string xtpx= "*******************";
Seed(key,true);
// XOR encrypt
xctx = Vernam(msg);
xtcx = System.Text.Encoding.ASCII.GetString(xctx);
// XOR decrypt
Seed(key,true);
xptx = Vernam(xtcx);
xtpx = System.Text.Encoding.ASCII.GetString(xptx);
Console.WriteLine("Message: "+msg);
Console.WriteLine("Key  : "+key);
Console.Write ("XOR  : ");
// output ciphertext as a string of hexadecimal digits
for (int n=0; n<xctx.Length; n++) Console.Write("{0:X2}", xctx[n]);
Console.WriteLine("\nXOR dcr: "+xtpx);
}
}
}
 
Output:
Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1C0636190B1260233B35125F1E1D0E2F4C5422
XOR dcr: a Top Secret secret

Common Lisp[edit]

(defpackage isaac
(:use cl))
 
(in-package isaac)
 
(deftype uint32 () '(unsigned-byte 32))
(deftype arru32 () '(simple-array uint32))
 
(defstruct state
(randrsl (make-array 256 :element-type 'uint32) :type arru32)
(randcnt 0 :type uint32)
(mm (make-array 256 :element-type 'uint32) :type arru32)
(aa 0 :type uint32)
(bb 0 :type uint32)
(cc 0 :type uint32))
 
(defparameter *global-state* (make-state))
 
;; Some helper functions to force 32-bit arithmetic.
;; COERCE32 will be used to ensure the 32-bit results from
;; the given operations.
(declaim (inline lsh32 rsh32 add32 mod32 xor32))
 
(defmacro coerce32 (thing)
`(ldb (byte 32 0) ,thing))
 
;; ASH is split into lsh32 and rsh32 to satisfy the compiler and
;; allow inlining.
(declaim (ftype (function (uint32 (unsigned-byte 6)) uint32) lsh32))
(defun lsh32 (integer count)
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0)))
(coerce32 (ash integer count)))
 
(declaim (ftype (function (uint32 uint32) uint32) rsh32 add32 mod32 xor32))
(defun rsh32 (integer count)
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0)))
(coerce32 (ash integer (- count))))
 
(defun add32 (x y)
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0)))
(coerce32 (+ x y)))
 
(defun mod32 (number divisor)
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0)))
(coerce32 (mod number divisor)))
 
(defun xor32 (x y)
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0)))
(coerce32 (logxor x y)))
 
(defmacro incf32 (place &optional (delta 1))
`(setf ,place (add32 ,place ,delta)))
 
(defun isaac (&optional (state *global-state*))
"The ISAAC function."
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0))
(type state state))
(with-slots (randrsl randcnt mm aa bb cc) state
(incf32 cc)
(incf32 bb cc)
(dotimes (i 256)
(let ((x (aref mm i)))
(setf aa (add32 (aref mm (mod32 (add32 i 128) 256))
(xor32 aa
(ecase (mod32 i 4)
(0 (lsh32 aa 13))
(1 (rsh32 aa 6))
(2 (lsh32 aa 2))
(3 (rsh32 aa 16))))))
(let ((y (add32 (aref mm (mod32 (rsh32 x 2) 256))
(add32 aa
bb))))
(setf (aref mm i) y)
(setf bb (add32 (aref mm (mod32 (rsh32 y 10) 256))
x))
(setf (aref randrsl i) bb))))
(setf randcnt 0)
(values)))
 
(defmacro mix (&rest places)
"The magic mixer that spits out code to mix the given places."
(let ((len (length places))
(kernel '#0=(11 -2 8 -16 10 -4 8 -9 . #0#)))
(rplacd (last places) places)
`(progn
,@(loop
for i from 0
for n in kernel
until (= i len)
append
(destructuring-bind (a b c d . rest) places
(declare (ignore rest))
(pop places)
`((setf ,a (xor32 ,a ,(if (> n 0) `(lsh32 ,b ,n) `(rsh32 ,b ,(- n)))))
(incf32 ,d ,a)
(incf32 ,b ,c)))))))
 
(defun replace-tree (value replacement tree)
"Replace all of the values in the given expression with the replacement."
(if (atom tree)
(if (equal tree value)
replacement
tree)
(cons (replace-tree value replacement (car tree))
(if (null (cdr tree))
nil
(replace-tree value replacement (cdr tree))))))
 
(defmacro unroller (index-name place-name places &body body)
"A helper for unrolling a section of a loop's index with the given places."
`(progn ,@(loop
for place in places
for i from 0 below (length places) append
`(,@(if (= i 0)
(replace-tree place-name place body)
(replace-tree index-name `(add32 ,index-name ,i)
(replace-tree place-name place body)))))))
 
(defun randinit (flag &optional (state *global-state*))
"Initialize the given state."
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0))
(type state state))
(with-slots (randrsl randcnt mm aa bb cc) state
(let* ((a #x9e3779b9) (b a) (c a) (d a) (e a) (f a) (g a) (h a))
(setf aa 0)
(setf bb 0)
(setf cc 0)
(loop repeat 4 do
(mix a b c d e f g h))
(loop for idx from 0 below 256 by 8 do
(when flag
(unroller idx place (a b c d e f g h)
(incf32 place (aref randrsl idx))))
(mix a b c d e f g h)
(unroller idx place (a b c d e f g h)
(setf (aref mm idx) place)))
(when flag
(loop for idx from 0 below 256 by 8 do
(unroller idx place (a b c d e f g h)
(incf32 place (aref mm idx)))
(mix a b c d e f g h)
(unroller idx place (a b c d e f g h)
(setf (aref mm idx) place)))))
(isaac state)
(setf randcnt 0)
(values)))
 
(defun i-random (&optional (state *global-state*))
"Get a random integer from the given state."
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0))
(type state state))
(with-slots (randrsl randcnt) state
(prog1 (aref randrsl randcnt)
(incf32 randcnt)
(when (> randcnt 255)
(isaac state)
(setf randcnt 0)))))
 
(defun i-rand-a (&optional (state *global-state*))
"Get a random printable character from the given state."
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0))
(type state state))
(add32 (mod32 (i-random state) 95) 32))
 
(defun i-seed (seed flag &optional (state *global-state*))
"Seed the given state with a string of up to 256 characters."
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0))
(type state state)
(type string seed))
(with-slots (randrsl mm) state
(dotimes (i 256)
(setf (aref mm i) 0))
(let ((m (length seed)))
(dotimes (i 256)
(setf (aref randrsl i)
(if (>= i m)
0
(char-code (char seed i))))))
(randinit flag state)
(values)))
 
(defun vernam (msg &optional (state *global-state*))
"Vernam encode MSG with STATE."
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0))
(type state state)
(type string msg))
(let* ((l (length msg))
(v (make-string l)))
(dotimes (i l)
(setf (aref v i) (code-char (logxor (i-rand-a state) (char-code (char msg i))))))
v))
 
;; Cipher modes: encipher, decipher, none
(defconstant +mod+ 95)
(defconstant +start+ 32)
 
(defun caesar (mode char shift modulo start)
"Caesar encode the given character."
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0))
(type uint32 char shift modulo start))
(when (eq mode 'decipher)
(setf shift (- shift)))
(let ((n (mod (+ (- char start) shift) modulo)))
(when (< n 0)
(incf n modulo))
(+ start n)))
 
(defun caesar-str (mode msg modulo start &optional (state *global-state*))
"Caesar encode or decode MSG with STATE."
(declare (optimize (speed 3) (safety 0) (space 0) (debug 0))
(type string msg)
(type fixnum modulo start)
(type state state))
(let* ((l (length msg))
(c (make-string l)))
(dotimes (i l)
(setf (aref c i) (code-char (caesar mode (char-code (char msg i)) (i-rand-a state) modulo start))))
c))
 
(defun print-hex (string)
(loop for c across string do (format t "~2,'0x" (char-code c))))
 
(defun main-test ()
(let ((state (make-state))
(msg "a Top Secret secret")
(key "this is my secret key"))
(i-seed key t state)
(let ((vctx (vernam msg state))
(cctx (caesar-str 'encipher msg +mod+ +start+ state)))
(i-seed key t state)
(let ((vptx (vernam vctx state))
(cptx (caesar-str 'decipher cctx +mod+ +start+ state)))
(format t "Message: ~a~%" msg)
(format t "Key  : ~a~%" key)
(format t "XOR  : ")
(print-hex vctx)
(terpri)
(format t "XOR dcr: ~a~%" vptx)
(format t "MOD  : ")
(print-hex cctx)
(terpri)
(format t "MOD dcr: ~a~%" cptx))))
(values))
Output:
ISAAC> (main-test)
Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1C0636190B1260233B35125F1E1D0E2F4C5422
XOR dcr: a Top Secret secret
MOD    : 734270227D36772A783B4F2A5F206266236978
MOD dcr: a Top Secret secret

D[edit]

Improved from the C# version. XOR with decryption check.

import std.algorithm: min;
import std.algorithm: copy;
import std.typetuple: TypeTuple;
import std.typecons: staticIota;
 
struct ISAAC {
// External results.
private uint[mm.length] randResult;
private uint randCount;
 
// Internal state.
private uint[256] mm;
private uint aa, bb, cc;
 
 
private void isaac() pure nothrow @safe @nogc {
cc++; // cc just gets incremented once per mm.length results.
bb = bb + cc; // Then combined with bb.
 
foreach (immutable i, ref mmi; mm) {
immutable x = mm[i];
final switch (i % 4) { // Not enforced final switch.
case 0: aa ^= (aa << 13); break;
case 1: aa ^= (aa >> 6); break;
case 2: aa ^= (aa << 2); break;
case 3: aa ^= (aa >> 16); break;
}
 
aa = mm[(i + 128) % $] + aa;
immutable y = mm[(x >> 2) % $] + aa + bb;
bb = mm[(y >> 10) % $] + x;
randResult[i] = bb;
}
 
randCount = 0;
}
 
 
// If flag is true then use the contents of randResult to initialize mm.
private pure nothrow @safe @nogc static void mix(ref uint[8] a) {
alias shifts = TypeTuple!(11, 2, 8, 16, 10, 4, 8, 9);
/*static*/ foreach (immutable i, immutable sh; shifts) {
static if (i % 2 == 0)
a[i] ^= a[(i + 1) % $] << sh;
else
a[i] ^= a[(i + 1) % $] >> sh;
a[(i + 3) % $] += a[i];
a[(i + 1) % $] += a[(i + 2) % $];
}
}
 
 
private void randInit(bool flag)() pure nothrow @safe @nogc {
uint[8] a = 0x9E37_79B9; // The Golden Ratio.
aa = bb = cc = 0;
 
// Scramble it.
/*static*/ foreach (immutable i; staticIota!(0, 4))
mix(a);
 
// Fill in mm with messy stuff. Use all the information in the seed.
for (size_t i = 0; i < mm.length; i += 8) {
static if (flag)
a[] += randResult[i .. i + 8];
mix(a);
mm[i .. i + 8] = a[];
}
 
// Do a second pass to make all of the seed affect all of mm.
static if (flag) {
for (size_t i = 0; i < mm.length; i += 8) {
a[] += mm[i .. i + 8];
mix(a);
mm[i .. i + 8] = a[];
}
}
 
isaac(); // Fill in the first set of results.
randCount = 0; // Prepare to use the first set of results.
}
 
 
/// Seed ISAAC with a string.
/// Uses only the first randResult.length ubytes.
public void iSeed(bool flag)(in ubyte[] seed) pure nothrow @safe @nogc {
mm[] = 0;
randResult[] = 0;
 
immutable n = min(randResult.length, seed.length);
copy(seed[0 .. n], randResult[0 .. n]);
 
randInit!flag(); // Initialize ISAAC with seed.
}
 
 
/// Get a random uint.
private uint iRandom() pure nothrow @safe @nogc {
immutable result = randResult[randCount];
 
randCount++;
if (randCount > (randResult.length - 1)) {
isaac();
randCount = 0;
}
 
return result;
}
 
 
/// Get a random character in printable ASCII range.
private ubyte iRandA() pure nothrow @safe @nogc {
return iRandom() % 95 + 32;
}
 
 
/// XOR encrypt on random stream.
/// buffer must be as large as message or larger.
public ubyte[] vernam(in ubyte[] message, ubyte[] buffer)
pure nothrow @safe @nogc
in {
assert(buffer.length >= message.length);
} out(result) {
assert(result.length == message.length);
} body {
auto v = buffer[0 .. message.length];
 
// XOR message.
foreach (immutable i, immutable msgi; message)
v[i] = (iRandA() ^ msgi);
return v;
}
 
 
/// XOR encrypt on random stream.
public ubyte[] vernam(in ubyte[] message) pure nothrow @safe {
return vernam(message, new ubyte[message.length]);
}
}
 
 
void main() {
import std.stdio, std.string;
 
immutable message = "a Top Secret secret";
immutable key = "this is my secret key";
 
writeln("Message  : ", message);
writeln("Key  : ", key);
 
ISAAC cipher;
 
// Encrypt.
// iSeed uses only the first ISAAC.randResult.length ubytes.
cipher.iSeed!true(key.representation);
const encrypted = cipher.vernam(message.representation);
 
// Output ciphertext as a string of hexadecimal digits.
writefln("Encrypted: %(%02X%)", encrypted);
 
// Decrypt.
cipher.iSeed!true(key.representation);
const decrypted = cipher.vernam(encrypted);
 
writeln("Decrypted: ", decrypted.assumeUTF);
}
Output:
Message  : a Top Secret secret
Key      : this is my secret key
Encrypted: 1C0636190B1260233B35125F1E1D0E2F4C5422
Decrypted: a Top Secret secret

Delphi[edit]

Translation of Pascal.

 
{$apptype console}
PROGRAM RosettaIsaac;
USES SysUtils;
 
// TASK globals
VAR msg : STRING = 'a Top Secret secret';
VAR key : STRING = 'this is my secret key';
VAR xctx: STRING = ''; // XOR ciphertext
VAR mctx: STRING = ''; // MOD ciphertext
 
// ISAAC globals
// external results
VAR randrsl: ARRAY[0..256] OF CARDINAL;
VAR randcnt: cardinal;
// internal state
VAR mm: ARRAY[0..256] OF CARDINAL;
VAR aa: CARDINAL=0; bb: CARDINAL=0; cc: CARDINAL=0;
 
 
PROCEDURE Isaac;
VAR i,x,y: CARDINAL;
BEGIN
cc := cc + 1; // cc just gets incremented once per 256 results
bb := bb + cc; // then combined with bb
 
FOR i := 0 TO 255 DO BEGIN
x := mm[i];
CASE (i mod 4) OF
0: aa := aa xor (aa shl 13);
1: aa := aa xor (aa shr 6);
2: aa := aa xor (aa shl 2);
3: aa := aa xor (aa shr 16);
END;
aa := mm[(i+128) mod 256] + aa;
y := mm[(x shr 2) mod 256] + aa + bb;
mm[i] := y;
bb := mm[(y shr 10) mod 256] + x;
randrsl[i]:= bb;
END;
// this reset was not in original readable.c!
randcnt:=0; // prepare to use the first set of results
END; {Isaac}
 
 
// if (flag==TRUE), then use the contents of randrsl[] to initialize mm[].
PROCEDURE mix(VAR a,b,c,d,e,f,g,h: CARDINAL);
BEGIN
a := a xor b shl 11; d:=d+a; b:=b+c;
b := b xor c shr 2; e:=e+b; c:=c+d;
c := c xor d shl 8; f:=f+c; d:=d+e;
d := d xor e shr 16; g:=g+d; e:=e+f;
e := e xor f shl 10; h:=h+e; f:=f+g;
f := f xor g shr 4; a:=a+f; g:=g+h;
g := g xor h shl 8; b:=b+g; h:=h+a;
h := h xor a shr 9; c:=c+h; a:=a+b;
END; {mix}
 
 
PROCEDURE iRandInit(flag: BOOLEAN);
VAR i,a,b,c,d,e,f,g,h: CARDINAL;
BEGIN
aa:=0; bb:=0; cc:=0;
a:=$9e3779b9; // the golden ratio
 
b:=a; c:=a; d:=a; e:=a; f:=a; g:=a; h:=a;
 
FOR i := 0 TO 3 DO // scramble it
mix(a,b,c,d,e,f,g,h);
 
i:=0;
REPEAT // fill in mm[] with messy stuff
IF flag THEN BEGIN // use all the information in the seed
a:=a+randrsl[i ]; b:=b+randrsl[i+1]; c:=c+randrsl[i+2]; d:=d+randrsl[i+3];
e:=e+randrsl[i+4]; f:=f+randrsl[i+5]; g:=g+randrsl[i+6]; h:=h+randrsl[i+7];
END;
 
mix(a,b,c,d,e,f,g,h);
mm[i ]:=a; mm[i+1]:=b; mm[i+2]:=c; mm[i+3]:=d;
mm[i+4]:=e; mm[i+5]:=f; mm[i+6]:=g; mm[i+7]:=h;
i:=i+8;
UNTIL i>255;
 
IF (flag) THEN BEGIN
// do a second pass to make all of the seed affect all of mm
i:=0;
REPEAT
a:=a+mm[i ]; b:=b+mm[i+1]; c:=c+mm[i+2]; d:=d+mm[i+3];
e:=e+mm[i+4]; f:=f+mm[i+5]; g:=g+mm[i+6]; h:=h+mm[i+7];
mix(a,b,c,d,e,f,g,h);
mm[i ]:=a; mm[i+1]:=b; mm[i+2]:=c; mm[i+3]:=d;
mm[i+4]:=e; mm[i+5]:=f; mm[i+6]:=g; mm[i+7]:=h;
i:=i+8;
UNTIL i>255;
END;
isaac(); // fill in the first set of results
randcnt:=0; // prepare to use the first set of results
END; {randinit}
 
 
{ Seed ISAAC with a given string.
The string can be any size. The first 256 values will be used.}

PROCEDURE iSeed(seed: STRING; flag: BOOLEAN);
VAR i,m: CARDINAL;
BEGIN
FOR i:= 0 TO 255 DO mm[i]:=0;
m := Length(seed)-1;
FOR i:= 0 TO 255 DO BEGIN
// in case seed has less than 256 elements
IF i>m THEN randrsl[i]:=0
// Pascal strings are 1-based
ELSE randrsl[i]:=ord(seed[i+1]);
END;
// initialize ISAAC with seed
iRandInit(flag);
END; {iSeed}
 
 
{ Get a random 32-bit value 0..MAXINT }
FUNCTION iRandom : Cardinal;
BEGIN
result := randrsl[randcnt];
inc(randcnt);
IF (randcnt >255) THEN BEGIN
Isaac();
randcnt := 0;
END;
END; {iRandom}
 
 
{ Get a random character in printable ASCII range }
FUNCTION iRandA: BYTE;
BEGIN
result := iRandom mod 95 + 32;
END;
 
 
{ convert an ASCII string to a hexadecimal string }
FUNCTION ascii2hex(s: STRING): STRING;
VAR i,l: CARDINAL;
BEGIN
result := '';
l := Length(s);
FOR i := 1 TO l DO
result := result + IntToHex(ord(s[i]),2);
END;
 
 
{ XOR encrypt on random stream. Output: string of hex chars }
FUNCTION Vernam(msg: STRING): STRING;
VAR i: CARDINAL;
BEGIN
result := '';
FOR i := 1 to length(msg) DO
result := result + chr(iRandA xor ord(msg[i]));
result := ascii2hex(result);
END;
 
 
{ Get position of the letter in chosen alphabet }
FUNCTION letternum(letter, start: CHAR): byte;
BEGIN
result := (ord(letter)-ord(start));
END;
 
 
{ Caesar-shift a character <shift> places: Generalized Vigenere }
FUNCTION Caesar(ch: CHAR; shift, modulo: INTEGER; start: CHAR): CHAR;
VAR n: INTEGER;
BEGIN
n := letternum(ch,start) + shift;
n := n MOD modulo;
result := chr(ord(start)+n);
END;
 
{ Vigenere mod 95 encryption. Output: string of hex chars }
FUNCTION Vigenere(msg: STRING): STRING;
VAR i: CARDINAL;
BEGIN
result := '';
FOR i := 1 to length(msg) DO
result := result + Caesar(msg[i],iRandA,95,' ');
result := ascii2hex(result);
END;
 
 
BEGIN
// 1) seed ISAAC with the key
iSeed(key,true);
// 2) Vernam XOR encryption
xctx := Vernam(msg);
// 3) MOD encryption
mctx := Vigenere(msg);
// program output
Writeln('Message: ',msg);
Writeln('Key  : ',key);
Writeln('XOR  : ',xctx);
Writeln('MOD  : ',mctx);
END.
 
Output:
Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1C0636190B1260233B35125F1E1D0E2F4C5422
MOD    : 734270227D36772A783B4F2A5F206266236978

ECMAScript[edit]

Works with: node.js version 0.10.32
Translation of: C#
randrsl = new Uint32Array(256);
randcnt = 0;
mm = new Uint32Array(256);
aa = 0;
bb = 0;
cc = 0;
 
function isaac() {
cc++;
bb += cc;
for(var i = 0; i < 256; i++) {
var x = mm[i];
var sw = i & 3;
if(sw == 0) aa = aa ^ (aa << 13);
else if(sw == 1) aa = aa ^ (aa >>> 6);
else if(sw == 2) aa = aa ^ (aa << 2);
else if(sw == 3) aa = aa ^ (aa >>> 16);
aa = mm[(i+128) & 255] + aa;
mm[i] = mm[(x >>> 2) & 255] + aa + bb;
bb = mm[(mm[i] >>> 10) & 255] + x;
randrsl[i] = bb;
}
}
 
function isaac_mix(x) {
x[0] = x[0] ^ x[1] << 11; x[3]+=x[0]; x[1]+=x[2];
x[1] = x[1] ^ x[2] >>> 2; x[4]+=x[1]; x[2]+=x[3];
x[2] = x[2] ^ x[3] << 8; x[5]+=x[2]; x[3]+=x[4];
x[3] = x[3] ^ x[4] >>> 16; x[6]+=x[3]; x[4]+=x[5];
x[4] = x[4] ^ x[5] << 10; x[7]+=x[4]; x[5]+=x[6];
x[5] = x[5] ^ x[6] >>> 4; x[0]+=x[5]; x[6]+=x[7];
x[6] = x[6] ^ x[7] << 8; x[1]+=x[6]; x[7]+=x[0];
x[7] = x[7] ^ x[0] >>> 9; x[2]+=x[7]; x[0]+=x[1];
}
 
function isaac_init(flag) {
var x = Uint32Array([2654435769, 2654435769, 2654435769, 2654435769,
2654435769, 2654435769, 2654435769, 2654435769]);
aa=0, bb=0, cc=0;
isaac_mix(x); isaac_mix(x); isaac_mix(x); isaac_mix(x);
var i = 0;
while(i < 255) {
if(flag) for(var j = 0; j < 8; j++) x[j] += randrsl[i+j];
isaac_mix(x);
for(var j = 0; j < 8; j++) mm[i+j] = x[j];
i += 8;
}
if(flag) {
var i = 0;
while(i < 255) {
for(var j = 0; j < 8; j++) x[j] += mm[i+j];
isaac_mix(x);
for(var j = 0; j < 8; j++) mm[i+j] = x[j];
i += 8;
}
}
isaac();
randcnt = 0;
}
 
function isaac_seed(string, flag) {
mm = new Uint32Array(256);
randrsl = new Uint32Array(256);
var m = string.length;
for(var i = 0; i < m; i++) randrsl[i] = string.charCodeAt(i);
isaac_init(flag);
}
 
function isaac_random() {
var out = randrsl[randcnt++];
if(randcnt > 255) {
isaac();
randcnt = 0;
}
return out
}
 
function vernam(msg) {
var out = "";
for(var i = 0; i < msg.length; i++) {
var ra = isaac_random() % 95 + 32;
out += String.fromCharCode(ra ^ msg.charCodeAt(i));
}
return out;
}
 
function printable_hex(s) {
out = "";
for(var i = 0; i < s.length; i++)
out += (s.charCodeAt(i) / 16 > 1 ? '' : '0') + s.charCodeAt(i).toString(16);
return out;
}
 
function run_isaac(key, msg)
{
isaac_seed(key, true);
 
// XOR encrypt
var xctx = vernam(msg);
 
// XOR decrypt
isaac_seed(key, true);
var xptx = vernam(xctx);
 
return [xctx, xptx]
}
 
var key = 'this is my secret key'
var msg = 'a Top Secret secret'
console.log('key: '+key)
console.log('msg: '+msg)
var z = run_isaac(key, msg)
xctx = z[0];
xptx = z[1];
console.log('xor: '+printable_hex(xctx))
console.log('decrypted: '+xptx)
Output:
key: this is my secret key
msg: a Top Secret secret
xor: 1c0636190b1260233b35125f1e1d0e2f4c5422
decrypted: a Top Secret secret

FreeBASIC[edit]

Translation of: C
' version 03-11-2016
' compile with: fbc -s console
 
Dim Shared As UInteger<32> randrsl(256), randcnt
Static Shared As UInteger<32> mm(256)
Static Shared As UInteger<32> aa, bb ,cc
 
Sub ISAAC()
 
Dim As UInteger<32> i, x, y
 
cc = cc + 1
bb = bb + cc
 
For i = 0 To 256 -1
x = mm(i)
Select Case (i Mod 4)
Case 0 : aa = aa Xor (aa Shl 13)
Case 1 : aa = aa Xor (aa Shr 6)
Case 2 : aa = aa Xor (aa Shl 2)
Case 3 : aa = aa Xor (aa Shr 16)
End Select
aa = mm((i+128) Mod 256) + aa
y = mm((x Shr 2) Mod 256) + aa + bb : mm(i) = y
bb = mm((y Shr 10) Mod 256) + x : randrsl(i) = bb
Next
 
randcnt = 0
 
End Sub
 
 
#Macro mix(a, b, c, d, e, f, g, h)
 
a Xor= b Shl 11 : d += a : b += c
b Xor= c Shr 2  : e += b : c += d
c Xor= d Shl 8  : f += c : d += e
d Xor= e Shr 16 : g += d : e += f
e Xor= f Shl 10 : h += e : f += g
f Xor= g Shr 4  : a += f : g += h
g Xor= h Shl 8  : b += g : h += a
h Xor= a Shr 9  : c += h : a += b
 
#EndMacro
 
Sub randinit(flag As Long)
 
Dim As Long i
Dim As UInteger<32> a = &H9e3779b9 '/* the golden ratio *
Dim As UInteger<32> b = &H9e3779b9
Dim As UInteger<32> c = &H9e3779b9
Dim As UInteger<32> d = &H9e3779b9
Dim As UInteger<32> e = &H9e3779b9
Dim As UInteger<32> f = &H9e3779b9
Dim As UInteger<32> g = &H9e3779b9
Dim As UInteger<32> h = &H9e3779b9
aa = 0 : bb = 0 : cc = 0
 
For i = 0 To 3
mix(a, b, c, d, e, f, g, h)
Next
 
For i = 0 To 255 Step 8
If flag = 1 Then
a += randrsl(i ) : b += randrsl(i +1)
c += randrsl(i +2) : d += randrsl(i +3)
e += randrsl(i +4) : f += randrsl(i +5)
g += randrsl(i +6) : h += randrsl(i +7)
 
mix(a, b, c, d, e, f, g, h)
mm(i ) = a : mm(i +1) = b : mm(i +2) = c : mm(i +3) = d
mm(i +4) = e : mm(i +5) = f : mm(i +6) = g : mm(i +7) = h
End If
Next
 
If flag = 1 Then
For i = 0 To 255 Step 8
a += mm(i ) : b += mm(i +1)
c += mm(i +2) : d += mm(i +3)
e += mm(i +4) : f += mm(i +5)
g += mm(i +6) : h += mm(i +7)
 
mix(a, b, c, d, e, f, g, h)
mm(i )= a : mm(i +1) = b : mm(i +2) = c : mm(i +3) = d
mm(i +4)= e : mm(i +5) = f : mm(i +6) = g : mm(i +7) = h
Next
End If
 
ISAAC()
randcnt = 0
 
End Sub
 
' // Get a random 32-bit value 0..MAXINT
Function iRandom() As UInteger<32>
 
Dim As UInteger<32> r = randrsl(randcnt)
randcnt += 1
If randcnt > 255 Then
ISAAC()
randcnt = 0
End If
 
Return r
 
End Function
 
' // Get a random character in printable ASCII range
Function iRandA() As UByte
 
Return iRandom() Mod 95 +32
 
End Function
 
' // Seed ISAAC with a string
Sub iSeed(seed As String, flag As Long)
 
Dim As ULong i, m = Len(seed) -1
 
For i = 0 To 255
mm(i) = 0
Next
 
For i = 0 To 255
 
If i > m Then
randrsl(i) = 0
Else
randrsl(i) = seed[i]
End If
 
Next
 
randinit(flag)
 
End Sub
 
' // maximum length of message
'#define MAXMSG 4096
#Define _MOD_ 95 ' mod is FreeBASIC keyword
#Define _START_ 32 ' start is used as variable name
 
' // cipher modes for Caesar
Enum ciphermode
mEncipher
mDecipher
mNone
End Enum
 
' // XOR cipher on random stream. Output: ASCII string
' no maximum lenght for input and output string
Function Vernam(msg As String) As String
 
Dim As ULong i
Dim As String v
 
For i = 0 To Len(msg) -1
v += Chr(iRandA() Xor msg[i])
Next
 
Return v
 
End Function
 
' // Caesar-shift a printable character
Function Ceasar(m As ciphermode, ch As UByte, shift As UByte, modulo As UByte, _
start As UByte) As UByte
 
' FreeBASIC Mod does not handle negative numbers correctly
' also there is litte problem with shift (declared UByte)
' the IIF() statement helps with shift
' to avoid a negative n a 8 times modulo is added
' modulo * 8 get translateted by FreeBASIC to modulo shl 3
Dim As Long n = (ch - start) + IIf(m = mDecipher, -shift, shift) + modulo * 8
n = n Mod modulo
Return start + n
 
End Function
 
' // Caesar-shift a string on a pseudo-random stream
Function CeasarStr(m As ciphermode, msg As String, modulo As UByte, _
start As UByte) As String
 
Dim As Long i
Dim As String v
 
For i = 0 To Len(msg) -1
v += Chr(Ceasar(m, msg[i], iRandA(), modulo, start))
Next
 
Return v
 
End Function
 
' ------=< MAIN >=------
 
Dim As Long n, l
Dim As String msg = "a Top Secret secret"
Dim As String key = "this is my secret key"
 
Dim As String vctx, vptx
Dim As String cctx, cptx
 
l = Len(msg)
' // Encrypt: Vernam XOR
iSeed(key, 1)
vctx = Vernam(msg)
' // Encrypt: Caesar
cctx = CeasarStr(mEncipher, msg, _mod_, _start_)
' // Decrypt: Vernam XOR
iSeed(key, 1)
vptx = Vernam(vctx)
' // Decrypt: Caesar
cptx = CeasarStr(mDecipher, cctx, _mod_, _start_)
Print "message: "; msg
Print " key: "; key
Print " XOR: ";
' // Output Vernam ciphertext as a string of hex digits
For n = 0 To l -1
Print Hex(vctx[n], 2);
Next
Print
' // Output Vernam decrypted plaintext
Print "XOR dcr: "; vptx
' // Caesar
Print " MOD: ";
' // Output Caesar ciphertext as a string of hex digits
For n= 0 To l -1
Print Hex(cctx[n], 2);
Next
Print
' // Output Caesar decrypted plaintext
Print "MOD dcr: " ; cptx
 
' empty keyboard buffer
While InKey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End
Output:
message: a Top Secret secret
    key: this is my secret key
    XOR: 1C0636190B1260233B35125F1E1D0E2F4C5422
XOR dcr: a Top Secret secret
    MOD: 734270227D36772A783B4F2A5F206266236978
MOD dcr: a Top Secret secret

Go[edit]

XOR version

package main
 
import "fmt"
 
const (
msg = "a Top Secret secret"
key = "this is my secret key"
)
 
func main() {
var z state
z.seed(key)
fmt.Println("Message: ", msg)
fmt.Println("Key  : ", key)
fmt.Println("XOR  : ", z.vernam(msg))
}
 
type state struct {
aa, bb, cc uint32
mm [256]uint32
randrsl [256]uint32
randcnt int
}
 
func (z *state) isaac() {
z.cc++
z.bb += z.cc
for i, x := range z.mm {
switch i % 4 {
case 0:
z.aa = z.aa ^ z.aa<<13
case 1:
z.aa = z.aa ^ z.aa>>6
case 2:
z.aa = z.aa ^ z.aa<<2
case 3:
z.aa = z.aa ^ z.aa>>16
}
z.aa += z.mm[(i+128)%256]
y := z.mm[x>>2%256] + z.aa + z.bb
z.mm[i] = y
z.bb = z.mm[y>>10%256] + x
z.randrsl[i] = z.bb
}
}
 
func (z *state) randInit() {
const gold = uint32(0x9e3779b9)
a := [8]uint32{gold, gold, gold, gold, gold, gold, gold, gold}
mix1 := func(i int, v uint32) {
a[i] ^= v
a[(i+3)%8] += a[i]
a[(i+1)%8] += a[(i+2)%8]
}
mix := func() {
mix1(0, a[1]<<11)
mix1(1, a[2]>>2)
mix1(2, a[3]<<8)
mix1(3, a[4]>>16)
mix1(4, a[5]<<10)
mix1(5, a[6]>>4)
mix1(6, a[7]<<8)
mix1(7, a[0]>>9)
}
for i := 0; i < 4; i++ {
mix()
}
for i := 0; i < 256; i += 8 {
for j, rj := range z.randrsl[i : i+8] {
a[j] += rj
}
mix()
for j, aj := range a {
z.mm[i+j] = aj
}
}
for i := 0; i < 256; i += 8 {
for j, mj := range z.mm[i : i+8] {
a[j] += mj
}
mix()
for j, aj := range a {
z.mm[i+j] = aj
}
}
z.isaac()
}
 
func (z *state) seed(seed string) {
for i, r := range seed {
if i == 256 {
break
}
z.randrsl[i] = uint32(r)
}
z.randInit()
}
 
func (z *state) random() (r uint32) {
r = z.randrsl[z.randcnt]
z.randcnt++
if z.randcnt == 256 {
z.isaac()
z.randcnt = 0
}
return
}
 
func (z *state) randA() byte {
return byte(z.random()%95 + 32)
}
 
func (z *state) vernam(msg string) string {
b := []byte(msg)
for i := range b {
b[i] ^= z.randA()
}
return fmt.Sprintf("%X", b)
}
Output:
Message:  a Top Secret secret
Key    :  this is my secret key
XOR    :  1C0636190B1260233B35125F1E1D0E2F4C5422

Haskell[edit]

import Data.Array
import Data.Bits
import Data.Char
import Data.Word
import Data.List
import Numeric
 
type IArray = Array Word32 Word32
 
data IsaacState = IState
{ randrsl :: IArray
, randcnt :: Word32
, mm :: IArray
, aa :: Word32
, bb :: Word32
, cc :: Word32
}
 
instance Show IsaacState where
show (IState _ cnt _ a b c) = show cnt ++ " " ++ show a ++ " " ++ show b ++ " " ++ show c
 
toHex :: Char -> String
toHex c = showHex (fromEnum c) ""
 
hexify :: String -> String
hexify = map toUpper . concatMap toHex
 
toNum :: Char -> Word32
toNum = fromIntegral . fromEnum
 
toChar :: Word32 -> Char
toChar = toEnum . fromIntegral
 
golden :: Word32
golden = 0x9e3779b9
 
-- Mix up an ordering of words.
mix :: [Word32] -> [Word32]
mix set = foldl aux set [11, -2, 8, -16, 10, -4, 8, -9]
where
aux [a,b,c,d,e,f,g,h] x = [b + c, c, d + a', e, f, g, h, a']
where a' = a `xor` (b `shift` x)
 
-- Generate the next 256 words.
isaac :: IsaacState -> IsaacState
isaac (IState rsl _ m a b c) = IState rsl'
0 m' a' b' c'
where
c' = c + 1
(rsl'
, m', a', b') = foldl aux (rsl, m, a, b) $ zip [0..255] $ cycle [13, -6, 2, -16]
aux (rsl, m, a, b) (i, s) = (rsl'
, m', a', b')
where x = m ! i
a'
= (a `xor` (a `shift` s)) + m ! ((i + 128) `mod` 256)
y = a' + b + m ! ((x `shift` (-2)) `mod` 256)
m'
= m // [(i,y)]
b' = x + m' ! ((y `shift` (-10)) `mod` 256)
rsl' = rsl // [(i,b')]
 
-- Given a seed value in randrsl, initialize/mixup the state.
randinit :: IsaacState -> Bool -> IsaacState
randinit state flag = isaac (IState randrsl' 0 m 0 0 0)
where
firstSet = (iterate mix $ replicate 8 golden) !! 4
iter _ _ [] = []
iter flag set rsl =
let (rslH, rslT) = splitAt 8 rsl
set'
= mix $ if flag
then zipWith (+) set rslH
else set
in set' ++ iter flag set' rslT
randrsl' = randrsl state
firstPass = iter flag firstSet $ elems randrsl'

set' = drop (256 - 8) firstPass
secondPass = if flag
then iter True set'
firstPass
else firstPass
m = array (0, 255) $ zip [0..] secondPass
 
-- Given a string seed, optionaly use it to generate a new state.
seed :: String -> Bool -> IsaacState
seed key flag =
let m = array (0, 255) $ zip [0..255] $ repeat 0
rsl = m // zip [0..] (map toNum key)
state = IState rsl 0 m 0 0 0
in randinit state flag
 
-- Produce a random word and the next state from the given state.
random :: IsaacState -> (Word32, IsaacState)
random state@(IState rsl cnt m a b c) =
let r = rsl ! cnt
state' = if cnt + 1 > 255
then isaac $ IState rsl 0 m a b c
else IState rsl (cnt + 1) m a b c
in (r, state'
)
 
-- Produce a stream of random words from the given state.
randoms :: IsaacState -> [Word32]
randoms = unfoldr $ Just . random
 
-- Produce a random printable/typable character in the ascii range
-- and the next state from the given state.
randA :: IsaacState -> (Char, IsaacState)
randA state =
let (r, state') = random state
in (toEnum $ fromIntegral $ (r `mod` 95) + 32, state'
)
 
-- Produce a stream of printable characters from the given state.
randAs :: IsaacState -> String
randAs = unfoldr $ Just . randA
 
-- Vernam encode/decode a string with the given state.
vernam :: IsaacState -> String -> String
vernam state msg = map toChar $ zipWith xor msg' randAs'
where
msg' = map toNum msg
randAs'
= map toNum $ randAs state
 
main :: IO ()
main = do
let msg = "a Top Secret secret"
key = "this is my secret key"
st = seed key True
ver = vernam st msg
unver = vernam st ver
putStrLn $ "Message: " ++ msg
putStrLn $ "Key  : " ++ key
putStrLn $ "XOR  : " ++ hexify ver
putStrLn $ "XOR dcr: " ++ unver
Output:
Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1C0636190B1260233B35125F1E1D0E2F4C5422
XOR dcr: a Top Secret secret

Haxe[edit]

Used a signed type rather then unsigned as unsigned 32bit type is not part of the default library. The effect of all operations with the exception of compare and mod are identical anyways. It is possible in Haxe to create your own 32bit unsigned type, but that is outside this exercise.

 
package src ;
import haxe.Int32;
import haxe.macro.Expr;
import haxe.ds.Vector;
 
typedef Ub4 = Int32;
 
enum Ciphermode {
mEncipher;
mDecipher;
mNone;
}
 
class Isaac
{
public var randrsl = new Vector<Ub4>(256);
public var randcnt:Ub4;
 
var mm = new Vector<Ub4>(256);
var aa:Ub4 = 0;
var bb:Ub4 = 0;
var cc:Ub4 = 0;
 
public function isaac():Void {
var x, y;
cc++;
bb += cc;
for (i in 0...256) {
x = mm[i];
aa ^= switch (i % 4) {//Haxe unification
case 0: aa << 13;
case 1: aa >>> 6;
case 2: aa << 2;
case 3: aa >>> 16;
default: 0;//never happens
}
aa = mm[(i + 128) % 256] + aa;
mm[i] = y = mm[(x >>> 2) % 256] + aa + bb;
randrsl[i] = bb = mm[(y >>> 10) % 256] + x;
}
}
 
macro static function mix(a:ExprOf<Ub4>, b:ExprOf<Ub4>, c:ExprOf<Ub4>, d:ExprOf<Ub4>,
e:ExprOf<Ub4>, f:ExprOf<Ub4>, g:ExprOf<Ub4>, h:ExprOf<Ub4>) {
return macro {
$a ^= $b << 11; $d += $a; $b += $c;
$b ^= $c >>> 2; $e += $b; $c += $d;
$c ^= $d << 8; $f += $c; $d += $e;
$d ^= $e >>> 16; $g += $d; $e += $f;
$e ^= $f << 10; $h += $e; $f += $g;
$f ^= $g >>> 4; $a += $f; $g += $h;
$g ^= $h << 8; $b += $g; $h += $a;
$h ^= $a >>> 9; $c += $h; $a += $b;
};
}
 
public function randinit(flag:Bool):Void {
var a, b, c, d, e, f, g, h, i;
aa = bb = cc = (0:Ub4);
a = b = c = d = e = f = g = h = (0x9e3779b9:Ub4); /* the golden ratio */
for (i in 0...4) mix(a, b, c, d, e, f, g, h); /* scramble it */
i = 0;
while (i < 256) { /* fill in mm[] with messy stuff */
if (flag) { /* use all the information in the seed */
a += randrsl[i]; b += randrsl[i + 1];
c += randrsl[i + 2]; d += randrsl[i + 3];
e += randrsl[i + 4]; f += randrsl[i + 5];
g += randrsl[i + 6]; h += randrsl[i + 7];
}
mix(a, b, c, d, e, f, g, h);
mm[i] = a; mm[i + 1] = b; mm[i + 2] = c; mm[i + 3] = d;
mm[i + 4] = e; mm[i + 5] = f; mm[i + 6] = g; mm[i + 7] = h;
i += 8;
}
if (flag) { /* do a second pass to make all of the seed affect all of mm */
i = 0;
while (i<256) {
a += mm[i]; b += mm[i + 1]; c += mm[i + 2]; d += mm[i + 3];
e += mm[i + 4]; f += mm[i + 5]; g += mm[i + 6]; h += mm[i + 7];
mix(a, b, c, d, e, f, g, h);
mm[i] = a; mm[i + 1] = b; mm[i + 2] = c; mm[i + 3] = d;
mm[i + 4] = e; mm[i + 5] = f; mm[i + 6] = g; mm[i + 7] = h;
i += 8;
}
}
isaac();
randcnt = 0;
}
 
public function iRandom():Ub4 {
var r = randrsl[randcnt];
++randcnt;
if (randcnt > 255) {
isaac();
randcnt = 0;
}
return r;
}
 
public function iRandA():Int32 {
return cast(cast(iRandom(),UInt) % 95 + 32,Int32);
}
 
public function iSeed(seed:String, flag:Bool):Void {
var m=seed.length-1;
for (i in 0...256) mm[i] = 0;
for (i in 0...256) if (i > m) randrsl[i] = 0; else randrsl[i] = seed.charCodeAt(i);
randinit(flag);
}
 
inline static var modC = 95;
inline static var startC = 32;
 
public function vernam (msg:String):String {
var v="";
for (i in 0...msg.length) v += String.fromCharCode(iRandA() ^ msg.charCodeAt(i));
return v;
}
 
public function caesar(m:Ciphermode, ch:Int32, shift:Int32,
modulo:Int32, start:Int32):String {
var n:Int32;
if (m == mDecipher) n = ch - start - cast(shift,Int32);
else n = ch - start + cast(shift,Int32);
n %= modulo;
if (n < 0) n += modulo;
return String.fromCharCode(start + cast(n,Ub4));
}
 
public function caesarStr(m:Ciphermode, msg:String, modulo:Int32, start:Int32):String {
var c = "";
for (i in 0...msg.length)
c += caesar(m,msg.charCodeAt(i),iRandA(),modulo,start);
return c;
}
 
static public function main():Void {
var msg = "a Top Secret secret";
var key = "this is my secret key";
var cIsaac = new Isaac();
var vctx, vptx, cctx, cptx;
cIsaac.iSeed(key, true);
vctx = cIsaac.vernam(msg);
cctx = cIsaac.caesarStr(mEncipher, msg, modC, startC);
 
cIsaac.iSeed(key, true);
vptx = cIsaac.vernam(vctx);
cptx = cIsaac.caesarStr(mDecipher, cctx, modC, startC);
 
Sys.println("Message: " + msg);
Sys.println("Key  : " + key);
var hex = "";
for (i in 0...vctx.length) hex += StringTools.hex(vctx.charCodeAt(i), 2);
Sys.println("XOR  : " + hex);
Sys.println("XOR dcr: " + vptx);
hex = "";
for (i in 0...cctx.length) hex += StringTools.hex(cctx.charCodeAt(i), 2);
Sys.println("MOD  : " + hex);
Sys.println("MOD dcr: " + cptx);
}
}
 
Output:
Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1C0636190B1260233B35125F1E1D0E2F4C5422
XOR dcr: a Top Secret secret
MOD    : 734270227D36772A783B4F2A5F206266236978
MOD dcr: a Top Secret secret

Java[edit]

Works with: Java version 1.6 or later

Java doesn't have unsigned data types, so it's important to use the logical right shift operator (>>>) instead of the arithmetic right shift operator (>>) on every right shift to maintain original semantics. Luckily, addition yields the same bits regardless of signedness, so most operations aren't affected.

This implementation extends the java.util.Random class, so it inherits methods that generate booleans, floats, doubles and longs, and can also generate numbers with Gaussian and uniform distribution. It can also be plugged in to standard library methods that receive a Random instance as a source of randomness. The toHexString() and main() methods are for demo purposes only and can be removed without changing main functionality.

import java.io.UnsupportedEncodingException;
import java.util.Arrays;
import java.util.Random;
 
 
public class IsaacRandom extends Random {
 
private static final long serialVersionUID = 1L;
 
private final int[] randResult = new int[256]; // output of last generation
private int valuesUsed; // the number of values already used up from randResult
 
// internal generator state
private final int[] mm = new int[256];
private int aa, bb, cc;
 
public IsaacRandom() {
super(0);
init(null);
}
 
public IsaacRandom(int[] seed) {
super(0);
setSeed(seed);
}
 
public IsaacRandom(String seed) {
super(0);
setSeed(seed);
}
 
private void generateMoreResults() {
cc++;
bb += cc;
 
for (int i=0; i<256; i++) {
int x = mm[i];
switch (i&3) {
case 0:
aa = aa^(aa<<13);
break;
case 1:
aa = aa^(aa>>>6);
break;
case 2:
aa = aa^(aa<<2);
break;
case 3:
aa = aa^(aa>>>16);
break;
}
aa = mm[i^128] + aa;
int y = mm[i] = mm[(x>>>2) & 0xFF] + aa + bb;
randResult[i] = bb = mm[(y>>>10) & 0xFF] + x;
}
 
valuesUsed = 0;
}
 
private static void mix(int[] s) {
s[0]^=s[1]<<11; s[3]+=s[0]; s[1]+=s[2];
s[1]^=s[2]>>>2; s[4]+=s[1]; s[2]+=s[3];
s[2]^=s[3]<<8; s[5]+=s[2]; s[3]+=s[4];
s[3]^=s[4]>>>16; s[6]+=s[3]; s[4]+=s[5];
s[4]^=s[5]<<10; s[7]+=s[4]; s[5]+=s[6];
s[5]^=s[6]>>>4; s[0]+=s[5]; s[6]+=s[7];
s[6]^=s[7]<<8; s[1]+=s[6]; s[7]+=s[0];
s[7]^=s[0]>>>9; s[2]+=s[7]; s[0]+=s[1];
}
 
private void init(int[] seed) {
if (seed != null && seed.length != 256) {
seed = Arrays.copyOf(seed, 256);
}
aa = bb = cc = 0;
int[] initState = new int[8];
Arrays.fill(initState, 0x9e3779b9); // the golden ratio
 
for (int i=0; i<4; i++) {
mix(initState);
}
 
for (int i=0; i<256; i+=8) {
if (seed != null) {
for (int j=0; j<8; j++) {
initState[j] += seed[i+j];
}
}
mix(initState);
for (int j=0; j<8; j++) {
mm[i+j] = initState[j];
}
}
 
if (seed != null) {
for (int i=0; i<256; i+=8) {
for (int j=0; j<8; j++) {
initState[j] += mm[i+j];
}
 
mix(initState);
 
for (int j=0; j<8; j++) {
mm[i+j] = initState[j];
}
}
}
 
valuesUsed = 256; // Make sure generateMoreResults() will be called by the next next() call.
}
 
@Override
protected int next(int bits) {
if (valuesUsed == 256) {
generateMoreResults();
assert(valuesUsed == 0);
}
int value = randResult[valuesUsed];
valuesUsed++;
return value >>> (32-bits);
}
 
@Override
public synchronized void setSeed(long seed) {
super.setSeed(0);
if (mm == null) {
// We're being called from the superclass constructor. We don't have our
// state arrays instantiated yet, and we're going to do proper initialization
// later in our own constructor anyway, so just ignore this call.
return;
}
int[] arraySeed = new int[256];
arraySeed[0] = (int) (seed & 0xFFFFFFFF);
arraySeed[1] = (int) (seed >>> 32);
init(arraySeed);
}
 
public synchronized void setSeed(int[] seed) {
super.setSeed(0);
init(seed);
}
 
public synchronized void setSeed(String seed) {
super.setSeed(0);
char[] charSeed = seed.toCharArray();
int[] intSeed = new int[charSeed.length];
for (int i=0; i<charSeed.length; i++) {
intSeed[i] = charSeed[i];
}
init(intSeed);
}
 
public int randomChar() {
long unsignedNext = nextInt() & 0xFFFFFFFFL; // The only way to force unsigned modulo behavior in Java is to convert to a long and mask off the copies of the sign bit.
return (int) (unsignedNext % 95 + 32); // nextInt(95) + 32 would yield a more equal distribution, but then we would be incompatible with the original C code
}
 
public enum CipherMode { ENCIPHER, DECIPHER, NONE };
 
public byte[] vernamCipher(byte[] input) {
byte[] result = new byte[input.length];
for (int i=0; i<input.length; i++) {
result[i] = (byte) (randomChar() ^ input[i]);
}
return result;
}
 
private static byte caesarShift(CipherMode mode, byte ch, int shift, byte modulo, byte start) {
if (mode == CipherMode.DECIPHER) {
shift = -shift;
}
int n = (ch-start) + shift;
n %= modulo;
if (n<0) {
n += modulo;
}
return (byte) (start + n);
}
 
public byte[] caesarCipher(CipherMode mode, byte[] input, byte modulo, byte start) {
byte[] result = new byte[input.length];
for (int i=0; i<input.length; i++) {
result[i] = caesarShift(mode, input[i], randomChar(), modulo, start);
}
return result;
}
 
private static String toHexString(byte[] input) {
// NOTE: This method prefers simplicity over performance.
StringBuilder sb = new StringBuilder(input.length*2);
for (byte b : input) {
sb.append(String.format("%02X", b));
}
return sb.toString();
}
 
public static void main(String[] args) {
final byte MOD = 95;
final byte START = 32;
 
String secret = "a Top Secret secret";
String key = "this is my secret key";
 
IsaacRandom random = new IsaacRandom(key);
byte[] vernamResult;
byte[] caesarResult;
String vernamDecrypted;
String caesarDecrypted;
try {
vernamResult = random.vernamCipher(secret.getBytes("ASCII"));
caesarResult = random.caesarCipher(CipherMode.ENCIPHER, secret.getBytes("ASCII"), MOD, START);
random.setSeed(key);
vernamDecrypted = new String(random.vernamCipher(vernamResult), "ASCII");
caesarDecrypted = new String(random.caesarCipher(CipherMode.DECIPHER, caesarResult, MOD, START), "ASCII");
} catch (UnsupportedEncodingException e) {
throw new InternalError("JVM isn't conforming - ASCII encoding isn't available");
}
System.out.printf("Message: %s\n", secret);
System.out.printf("Key  : %s\n", key);
System.out.printf("XOR  : %s\n", toHexString(vernamResult));
System.out.printf("XOR dcr: %s\n", vernamDecrypted);
System.out.printf("MOD  : %s\n", toHexString(caesarResult));
System.out.printf("MOD dcr: %s\n", caesarDecrypted);
}
}

Kotlin[edit]

Translation of: C
// version 1.1.3
 
/* external results */
val randrsl = IntArray(256)
var randcnt = 0
 
/* internal state */
val mm = IntArray(256)
var aa = 0
var bb = 0
var cc = 0
 
const val GOLDEN_RATIO = 0x9e3779b9.toInt()
 
fun isaac() {
cc++ // cc just gets incremented once per 256 results
bb += cc // then combined with bb
for (i in 0..255) {
val x = mm[i]
when (i % 4) {
0 -> aa = aa xor (aa shl 13)
1 -> aa = aa xor (aa ushr 6)
2 -> aa = aa xor (aa shl 2)
3 -> aa = aa xor (aa ushr 16)
}
aa += mm[(i + 128) % 256]
val y = mm[(x ushr 2) % 256] + aa + bb
mm[i] = y
bb = mm[(y ushr 10) % 256] + x
randrsl[i] = bb
}
randcnt = 0
}
 
/* if (flag == true), then use the contents of randrsl to initialize mm. */
fun mix(n: IntArray) {
n[0] = n[0] xor (n[1] shl 11); n[3] += n[0]; n[1] += n[2]
n[1] = n[1] xor (n[2] ushr 2); n[4] += n[1]; n[2] += n[3]
n[2] = n[2] xor (n[3] shl 8); n[5] += n[2]; n[3] += n[4]
n[3] = n[3] xor (n[4] ushr 16); n[6] += n[3]; n[4] += n[5]
n[4] = n[4] xor (n[5] shl 10); n[7] += n[4]; n[5] += n[6]
n[5] = n[5] xor (n[6] ushr 4); n[0] += n[5]; n[6] += n[7]
n[6] = n[6] xor (n[7] shl 8); n[1] += n[6]; n[7] += n[0]
n[7] = n[7] xor (n[0] ushr 9); n[2] += n[7]; n[0] += n[1]
}
 
fun randinit(flag: Boolean) {
aa = 0
bb = 0
cc = 0
val n = IntArray(8) { GOLDEN_RATIO }
for (i in 0..3) mix(n) // scramble the array
 
for (i in 0..255 step 8) { // fill in mm with messy stuff
if (flag) { // use all the information in the seed
for (j in 0..7) n[j] += randrsl[i + j]
}
mix(n)
for (j in 0..7) mm[i + j] = n[j]
}
 
if (flag) {
/* do a second pass to make all of the seed affect all of mm */
for (i in 0..255 step 8) {
for (j in 0..7) n[j] += mm[i + j]
mix(n)
for (j in 0..7) mm[i + j] = n[j]
}
}
 
isaac() // fill in the first set of results
randcnt = 0 // prepare to use the first set of results
}
 
/* As Kotlin doesn't (yet) support unsigned types, we need to use
Long here to get a random value in the range of a UInt */

fun iRandom(): Long {
val r = randrsl[randcnt++]
if (randcnt > 255) {
isaac()
randcnt = 0
}
return r.toLong() and 0xFFFFFFFFL
}
 
/* Get a random character (as Int) in printable ASCII range */
fun iRandA() = (iRandom() % 95 + 32).toInt()
 
/* Seed ISAAC with a string */
fun iSeed(seed: String, flag: Boolean) {
for (i in 0..255) mm[i] = 0
val m = seed.length
for (i in 0..255) {
/* in case seed has less than 256 elements */
randrsl[i] = if (i >= m) 0 else seed[i].toInt()
}
/* initialize ISAAC with seed */
randinit(flag)
}
 
/* XOR cipher on random stream. Output: ASCII string */
fun vernam(msg: String) : String {
val len = msg.length
val v = ByteArray(len)
for (i in 0 until len) {
v[i] = (iRandA() xor msg[i].toInt()).toByte()
}
return v.toString(charset("ASCII"))
}
 
/* constants for Caesar */
const val MOD = 95
const val START = 32
 
/* cipher modes for Caesar */
enum class CipherMode {
ENCIPHER, DECIPHER, NONE
}
 
/* Caesar-shift a printable character */
fun caesar(m: CipherMode, ch: Int, shift: Int, modulo: Int, start: Int): Char {
val sh = if (m == CipherMode.DECIPHER) -shift else shift
var n = (ch - start) + sh
n %= modulo
if (n < 0) n += modulo
return (start + n).toChar()
}
 
/* Caesar-shift a string on a pseudo-random stream */
fun caesarStr(m: CipherMode, msg: String, modulo: Int, start: Int): String {
val sb = StringBuilder(msg.length)
/* Caesar-shift message */
for (c in msg) {
sb.append(caesar(m, c.toInt(), iRandA(), modulo, start))
}
return sb.toString()
}
 
fun String.toHexByteString() =
this.map { "%02X".format(it.toInt()) }.joinToString("")
 
fun main(args: Array<String>) {
val msg = "a Top Secret secret"
val key = "this is my secret key"
 
// Vernam & Caesar ciphertext
iSeed(key, true)
val vctx = vernam(msg)
val cctx = caesarStr(CipherMode.ENCIPHER, msg, MOD, START)
 
// Vernam & Caesar plaintext
iSeed(key, true)
val vptx = vernam(vctx)
val cptx = caesarStr(CipherMode.DECIPHER, cctx, MOD, START)
 
// Program output
println("Message : $msg")
println("Key  : $key")
println("XOR  : ${vctx.toHexByteString()}")
println("XOR dcr : $vptx")
println("MOD  : ${cctx.toHexByteString()}")
println("MOD dcr : $cptx")
}
Output:
Message : a Top Secret secret
Key     : this is my secret key
XOR     : 1C0636190B1260233B35125F1E1D0E2F4C5422
XOR dcr : a Top Secret secret
MOD     : 734270227D36772A783B4F2A5F206266236978
MOD dcr : a Top Secret secret

Pascal[edit]

Free Pascal. A fully functional and complete reference solution of the task.

 
PROGRAM RosettaIsaac;
USES StrUtils;
 
TYPE iMode = (iEncrypt,iDecrypt);
// TASK globals
VAR msg : STRING = 'a Top Secret secret';
key : STRING = 'this is my secret key';
xctx: STRING = ''; // XOR ciphertext
mctx: STRING = ''; // MOD ciphertext
xptx: STRING = ''; // XOR decryption (plaintext)
mptx: STRING = ''; // MOD decryption (plaintext)
mode: iMode = iEncrypt;
 
// ISAAC globals
// external results
VAR randrsl: ARRAY[0..256] OF CARDINAL;
randcnt: cardinal;
// internal state
VAR mm: ARRAY[0..256] OF CARDINAL;
aa: CARDINAL=0; bb: CARDINAL=0; cc: CARDINAL=0;
 
 
PROCEDURE Isaac;
VAR i,x,y: CARDINAL;
BEGIN
cc := cc + 1; // cc just gets incremented once per 256 results
bb := bb + cc; // then combined with bb
 
FOR i := 0 TO 255 DO BEGIN
x := mm[i];
CASE (i mod 4) OF
0: aa := aa xor (aa shl 13);
1: aa := aa xor (aa shr 6);
2: aa := aa xor (aa shl 2);
3: aa := aa xor (aa shr 16);
END;
aa := mm[(i+128) mod 256] + aa;
y := mm[(x shr 2) mod 256] + aa + bb;
mm[i] := y;
bb := mm[(y shr 10) mod 256] + x;
randrsl[i]:= bb;
END;
// this reset was not in the original readable.c
randcnt:=0; // prepare to use the first set of results
END; {Isaac}
 
 
// if (flag==TRUE), then use the contents of randrsl[] to initialize mm[].
PROCEDURE mix(VAR a,b,c,d,e,f,g,h: CARDINAL);
BEGIN
a := a xor b shl 11; d:=d+a; b:=b+c;
b := b xor c shr 2; e:=e+b; c:=c+d;
c := c xor d shl 8; f:=f+c; d:=d+e;
d := d xor e shr 16; g:=g+d; e:=e+f;
e := e xor f shl 10; h:=h+e; f:=f+g;
f := f xor g shr 4; a:=a+f; g:=g+h;
g := g xor h shl 8; b:=b+g; h:=h+a;
h := h xor a shr 9; c:=c+h; a:=a+b;
END; {mix}
 
 
PROCEDURE iRandInit(flag: BOOLEAN);
VAR i,a,b,c,d,e,f,g,h: CARDINAL;
BEGIN
aa:=0; bb:=0; cc:=0;
a:=$9e3779b9; // the golden ratio
 
b:=a; c:=a; d:=a; e:=a; f:=a; g:=a; h:=a;
 
FOR i := 0 TO 3 DO // scramble it
mix(a,b,c,d,e,f,g,h);
 
i:=0;
REPEAT // fill in mm[] with messy stuff
IF flag THEN BEGIN // use all the information in the seed
a+=randrsl[i ]; b+=randrsl[i+1]; c+=randrsl[i+2]; d+=randrsl[i+3];
e+=randrsl[i+4]; f+=randrsl[i+5]; g+=randrsl[i+6]; h+=randrsl[i+7];
END;
 
mix(a,b,c,d,e,f,g,h);
mm[i ]:=a; mm[i+1]:=b; mm[i+2]:=c; mm[i+3]:=d;
mm[i+4]:=e; mm[i+5]:=f; mm[i+6]:=g; mm[i+7]:=h;
i+=8;
UNTIL i>255;
 
IF (flag) THEN BEGIN
// do a second pass to make all of the seed affect all of mm
i:=0;
REPEAT
a+=mm[i ]; b+=mm[i+1]; c+=mm[i+2]; d+=mm[i+3];
e+=mm[i+4]; f+=mm[i+5]; g+=mm[i+6]; h+=mm[i+7];
mix(a,b,c,d,e,f,g,h);
mm[i ]:=a; mm[i+1]:=b; mm[i+2]:=c; mm[i+3]:=d;
mm[i+4]:=e; mm[i+5]:=f; mm[i+6]:=g; mm[i+7]:=h;
i+=8;
UNTIL i>255;
END;
isaac(); // fill in the first set of results
randcnt:=0; // prepare to use the first set of results
END; {randinit}
 
 
{ Seed ISAAC with a given string.
The string can be any size. The first 256 values will be used.}

PROCEDURE iSeed(seed: STRING; flag: BOOLEAN);
VAR i,m: CARDINAL;
BEGIN
FOR i:= 0 TO 255 DO mm[i]:=0;
m := Length(seed)-1;
FOR i:= 0 TO 255 DO BEGIN
// in case seed has less than 256 elements
IF i>m THEN randrsl[i]:=0
// Pascal strings are 1-based
ELSE randrsl[i]:=ord(seed[i+1]);
END;
// initialize ISAAC with seed
iRandInit(flag);
END; {iSeed}
 
 
{ Get a random 32-bit value 0..MAXINT }
FUNCTION iRandom : Cardinal;
BEGIN
iRandom := randrsl[randcnt];
inc(randcnt);
IF (randcnt >255) THEN BEGIN
Isaac();
randcnt := 0;
END;
END; {iRandom}
 
 
{ Get a random character in printable ASCII range }
FUNCTION iRandA: BYTE;
BEGIN
iRandA := iRandom mod 95 + 32;
END;
 
 
{ convert an ASCII string to a hexadecimal string }
FUNCTION ascii2hex(s: STRING): STRING;
VAR i,l: CARDINAL;
BEGIN
ascii2hex := '';
l := Length(s);
FOR i := 1 TO l DO
ascii2hex += Dec2Numb(ord(s[i]),2,16);
END;
 
 
{ XOR encrypt on random stream. Output: ASCII string }
FUNCTION Vernam(msg: STRING): STRING;
VAR i: CARDINAL;
BEGIN
Vernam := '';
FOR i := 1 to length(msg) DO
Vernam += chr(iRandA xor ord(msg[i]));
END;
 
 
{ Get position of the letter in chosen alphabet }
FUNCTION letternum(letter, start: CHAR): byte;
BEGIN
letternum := (ord(letter)-ord(start));
END;
 
 
{ Caesar-shift a character <shift> places: Generalized Vigenere }
FUNCTION Caesar(m: iMode; ch: CHAR; shift, modulo: INTEGER; start: CHAR): CHAR;
VAR n: INTEGER;
BEGIN
IF m = iDecrypt THEN shift := -shift;
n := letternum(ch,start) + shift;
n := n MOD modulo;
IF n<0 THEN n += modulo;
Caesar := chr(ord(start)+n);
END;
 
 
{ Vigenere mod 95 encryption & decryption. Output: ASCII string }
FUNCTION Vigenere(msg: STRING; m: iMode): STRING;
VAR i: CARDINAL;
BEGIN
Vigenere := '';
FOR i := 1 to length(msg) DO
Vigenere += Caesar(m,msg[i],iRandA,95,' ');
END;
 
 
BEGIN
// 1) seed ISAAC with the key
iSeed(key,true);
// 2) Encryption
mode := iEncrypt;
// a) XOR (Vernam)
xctx := Vernam(msg);
// b) MOD (Vigenere)
mctx := Vigenere(msg,mode);
// 3) Decryption
mode := iDecrypt;
iSeed(key,true);
// a) XOR (Vernam)
xptx:= Vernam(xctx);
// b) MOD (Vigenere)
mptx:=Vigenere(mctx,mode);
// program output
Writeln('Message: ',msg);
Writeln('Key  : ',key);
Writeln('XOR  : ',ascii2hex(xctx));
Writeln('MOD  : ',ascii2hex(mctx));
Writeln('XOR dcr: ',xptx);
Writeln('MOD dcr: ',mptx);
END.
 
 
Output:
Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1C0636190B1260233B35125F1E1D0E2F4C5422
MOD    : 734270227D36772A783B4F2A5F206266236978
XOR dcr: a Top Secret secret
MOD dcr: a Top Secret secret

Perl[edit]

Perl has had an ISAAC module for a few years, and it is the recommended way to use ISAAC. This example uses Math::Random::ISAAC which is a pure Perl implementation, but will also allow faster operation if the Math::Random::ISAAC::XS module is installed.

Since ISAAC does not do its own seeding, the Bytes::Random::Secure module is recommended for general use as it includes ISAAC plus a portable way to get good entropy, as well as additional convenience functions.

use warnings;
use strict;
use Math::Random::ISAAC;
 
my $message = "a Top Secret secret";
my $key = "this is my secret key";
 
my $enc = xor_isaac($key, $message);
my $dec = xor_isaac($key, join "", pack "H*", $enc);
 
print "Message: $message\n";
print "Key  : $key\n";
print "XOR  : $enc\n";
print "XOR dcr: ", join("", pack "H*", $dec), "\n";
 
sub xor_isaac {
my($key, $msg) = @_;
 
# Make an ISAAC stream with the desired seed
my $rng = Math::Random::ISAAC->new( map { ord } split "",$key );
 
# Get ISAAC output in the order the task wants
my @iranda = map { $_ % 95 + 32 } # Alpha-tize as the task desires
reverse # MRI gives state from the end
map { $rng->irand } # Get random inputs...
0..255; # a state chunk at a time
# Encode:
join "", map { sprintf "%02X",$_ } # join hex digits
map { ord($_) ^ shift(@iranda) } # xor it with rand char
split "", $msg; # Take each character
}
Output:
Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1C0636190B1260233B35125F1E1D0E2F4C5422
XOR dcr: a Top Secret secret

PicoLisp[edit]

(de add32 @
(mod32 (pass +)) )
 
(de mod32 (N)
(& N `(hex "FFFFFFFF")) )
 
(de isaac()
(let (Y 0 S (-13 6 -2 16 .))
(setq *CC (add32 *CC 1))
(setq *BB (add32 *BB *CC))
(for (I . X) *MM
(set (nth *MM I)
(setq Y
(add32
(get *MM (inc (% (>> 2 X) 256)))
(setq *AA
(add32
(x| *AA (>> (pop 'S) *AA))
(get *MM (inc (% (+ 127 I) 256))) ) )
*BB ) ) )
(set (nth *RR I)
(setq *BB
(add32
(get *MM (inc (% (>> 10 Y) 256)))
X ) ) ) ) ) )
 
(de mixA()
(let S (-11 2 -8 16 -10 4 -8 9 .)
(for I 8
(set (nth *A I)
(mod32
(x|
(get *A I)
(mod32
(>>
(pop 'S)
(get *A (inc (% I 8))) ) ) ) ) )
(set (nth *A (inc (% (+ 2 I) 8)))
(add32
(get *A (inc (% (+ 2 I) 8)))
(get *A I) ) )
(set (nth *A (inc (% I 8)))
(add32
(get *A (inc (% I 8)))
(get *A (inc (% (inc I) 8))) ) ) ) ) )
 
(de iseed ()
(do 4
(mixA) )
(for (I 1 (> 256 I) (inc 'I 8))
(for (J I (> (+ 8 I) J) (inc J))
(set (nth *A (inc (% (dec J) 8)))
(add32
(get *A (inc (% (dec J) 8)))
(get *RR J) ) ) )
(mixA)
(for (J I (> (+ 8 I) J) (inc J))
(set (nth *MM J)
(get *A (inc (% (dec J) 8))) ) ) )
(for (I 1 (> 256 I) (inc 'I 8))
(for (J I (> (+ 8 I) J) (inc J))
(set (nth *A (inc (% (dec J) 8)))
(add32
(get *A (inc (% (dec J) 8)))
(get *MM J) ) ) )
(mixA)
(for (J I (> (+ 8 I) J) (inc J))
(set (nth *MM J)
(get *A (inc (% (dec J) 8))) ) ) )
(isaac) )
 
(let
(*AA 0
*BB 0
*CC 0
*MM (need 256 0)
*RC 0
*RR (need
-256
(mapcar
char
(head 256 (chop "this is my secret key")) ) 0 )
*A (need 8 `(hex "9E3779B9")) )
(iseed)
(println
(pack
(mapcar
'((B) (pad 2 (hex B)))
(make
(for I (mapcar char (chop "a Top Secret secret"))
(link
(x|
I
(+
32
(%
(get
*RR
(if (>= 256 (inc '*RC))
*RC
(isaac)
(one *RC) ) )
95 ) ) ) ) ) ) ) ) ) )
 
(bye)

Python[edit]

Works with: Python version 3.0 or later

Python doesn't have integer overflow (integers are handled as bignums if they don't fit into a machine word), so we need to emulate it manually by masking off the high bits after each addition and left shift.

This implementation extends the Random class of the built-in random module, so it automatically inherits methods for generating several distributions, as well as support for shuffling and sampling collections.

import random
import collections
 
INT_MASK = 0xFFFFFFFF # we use this to emulate 32-bit overflow semantics by masking off higher bits after operations
 
class IsaacRandom(random.Random):
"""
Random number generator using the ISAAC algorithm.
"""

 
def seed(self, seed=None):
"""
Initialize internal state.
 
The seed, if given, can be a string, an integer, or an iterable that contains
integers only. If no seed is given, a fixed default state is set up; unlike
our superclass, this class will not attempt to randomize the seed from outside sources.
"""

def mix():
init_state[0] ^= ((init_state[1]<<11)&INT_MASK); init_state[3] += init_state[0]; init_state[3] &= INT_MASK; init_state[1] += init_state[2]; init_state[1] &= INT_MASK
init_state[1] ^= (init_state[2]>>2) ; init_state[4] += init_state[1]; init_state[4] &= INT_MASK; init_state[2] += init_state[3]; init_state[2] &= INT_MASK
init_state[2] ^= ((init_state[3]<<8 )&INT_MASK); init_state[5] += init_state[2]; init_state[5] &= INT_MASK; init_state[3] += init_state[4]; init_state[3] &= INT_MASK
init_state[3] ^= (init_state[4]>>16) ; init_state[6] += init_state[3]; init_state[6] &= INT_MASK; init_state[4] += init_state[5]; init_state[4] &= INT_MASK
init_state[4] ^= ((init_state[5]<<10)&INT_MASK); init_state[7] += init_state[4]; init_state[7] &= INT_MASK; init_state[5] += init_state[6]; init_state[5] &= INT_MASK
init_state[5] ^= (init_state[6]>>4 ) ; init_state[0] += init_state[5]; init_state[0] &= INT_MASK; init_state[6] += init_state[7]; init_state[6] &= INT_MASK
init_state[6] ^= ((init_state[7]<<8 )&INT_MASK); init_state[1] += init_state[6]; init_state[1] &= INT_MASK; init_state[7] += init_state[0]; init_state[7] &= INT_MASK
init_state[7] ^= (init_state[0]>>9 ) ; init_state[2] += init_state[7]; init_state[2] &= INT_MASK; init_state[0] += init_state[1]; init_state[0] &= INT_MASK
 
super().seed(0) # give a chance for the superclass to reset its state - the actual seed given to it doesn't matter
if seed is not None:
if isinstance(seed, str):
seed = [ord(x) for x in seed]
elif isinstance(seed, collections.Iterable):
seed = [x & INT_MASK for x in seed]
elif isinstance(seed, int):
val = abs(seed)
seed = []
while val:
seed.append(val & INT_MASK)
val >>= 32
else:
raise TypeError('Seed must be string, integer or iterable of integer')
 
# make sure the seed list is exactly 256 elements long
if len(seed)>256:
del seed[256:]
elif len(seed)<256:
seed.extend([0]*(256-len(seed)))
 
self.aa = self.bb = self.cc = 0
self.mm = []
init_state = [0x9e3779b9]*8
 
for _ in range(4):
mix()
 
for i in range(0, 256, 8):
if seed is not None:
for j in range(8):
init_state[j] += seed[i+j]
init_state[j] &= INT_MASK
mix()
self.mm += init_state
 
if seed is not None:
for i in range(0, 256, 8):
for j in range(8):
init_state[j] += self.mm[i+j]
init_state[j] &= INT_MASK
mix()
for j in range(8):
self.mm[i+j] = init_state[j]
 
self.rand_count = 256
self.rand_result = [0]*256
 
def getstate(self):
return super().getstate(), self.aa, self.bb, self.cc, self.mm, self.rand_count, self.rand_result
 
def setstate(self, state):
super().setstate(state[0])
_, self.aa, self.bb, self.cc, self.mm, self.rand_count, self.rand_result = state
 
def _generate(self):
# Generate 256 random 32-bit values and save them in an internal field.
# The actual random functions will dish out these values to callers.
self.cc = (self.cc + 1) & INT_MASK
self.bb = (self.bb + self.cc) & INT_MASK
 
for i in range(256):
x = self.mm[i]
mod = i & 3
if mod==0:
self.aa ^= ((self.aa << 13) & INT_MASK)
elif mod==1:
self.aa ^= (self.aa >> 6)
elif mod==2:
self.aa ^= ((self.aa << 2) & INT_MASK)
else: # mod == 3
self.aa ^= (self.aa >> 16)
self.aa = (self.mm[i^128] + self.aa) & INT_MASK
y = self.mm[i] = (self.mm[(x>>2) & 0xFF] + self.aa + self.bb) & INT_MASK
self.rand_result[i] = self.bb = (self.mm[(y>>10) & 0xFF] + x) & INT_MASK
 
self.rand_count = 0
 
def next_int(self):
"""Return a random integer between 0 (inclusive) and 2**32 (exclusive)."""
if self.rand_count == 256:
self._generate()
result = self.rand_result[self.rand_count]
self.rand_count += 1
return result
 
def getrandbits(self, k):
"""Return a random integer between 0 (inclusive) and 2**k (exclusive)."""
result = 0
ints_needed = (k+31)//32
ints_used = 0
while ints_used < ints_needed:
if self.rand_count == 256:
self._generate()
ints_to_take = min(256-self.rand_count, ints_needed)
for val in self.rand_result[self.rand_count : self.rand_count+ints_to_take]:
result = (result << 32) | val
self.rand_count += ints_to_take
ints_used += ints_to_take
result &= ((1<<k)-1) # mask off extra bits, if any
return result
 
def random(self):
"""Return a random float between 0 (inclusive) and 1 (exclusive)."""
# A double stores 53 significant bits, so scale a 53-bit integer into the [0..1) range.
return self.getrandbits(53) * (2**-53)
 
def rand_char(self):
"""Return a random integer from the printable ASCII range [32..126]."""
return self.next_int() % 95 + 32
 
def vernam(self, msg):
"""
Encrypt/decrypt the given bytes object with the XOR algorithm, using the current generator state.
 
To decrypt an encrypted string, restore the state of the generator to the state it had
during encryption, then call this method with the encrypted string.
"""

return bytes((self.rand_char() & 0xFF) ^ x for x in msg)
 
# Constants for selecting Caesar operation modes.
ENCIPHER = 'encipher'
DECIPHER = 'decipher'
 
@staticmethod
def _caesar(ciphermode, ch, shift, modulo, start):
if ciphermode == IsaacRandom.DECIPHER:
shift = -shift
n = ((ch-start)+shift) % modulo
if n<0:
n += modulo
return start+n
 
def caesar(self, ciphermode, msg, modulo, start):
"""
Encrypt/decrypt a string using the Caesar algorithm.
 
For decryption to work, the generator must be in the same state it was during encryption,
and the same modulo and start parameters must be used.
 
ciphermode must be one of IsaacRandom.ENCIPHER or IsaacRandom.DECIPHER.
"""

return bytes(self._caesar(ciphermode, ch, self.rand_char(), modulo, start) for ch in msg)
 
if __name__=='__main__':
import binascii
 
def hexify(b):
return binascii.hexlify(b).decode('ascii').upper()
 
MOD = 95
START = 32
 
msg = 'a Top Secret secret'
key = 'this is my secret key'
isaac_random = IsaacRandom(key)
vernam_encoded = isaac_random.vernam(msg.encode('ascii'))
caesar_encoded = isaac_random.caesar(IsaacRandom.ENCIPHER, msg.encode('ascii'), MOD, START)
isaac_random.seed(key)
vernam_decoded = isaac_random.vernam(vernam_encoded).decode('ascii')
caesar_decoded = isaac_random.caesar(IsaacRandom.DECIPHER, caesar_encoded, MOD, START).decode('ascii')
 
print('Message:', msg)
print('Key  :', key)
print('XOR  :', hexify(vernam_encoded))
print('XOR dcr:', vernam_decoded)
print('MOD  :', hexify(caesar_encoded))
print('MOD dcr:', caesar_decoded)
 

Racket[edit]

- Imperative version:
Translation of: C
- Vigenère:
Translation of: Pascal

In the Pascal (and reference version) of the Vigenère encryption, the state engine is not reset after having been used for the XOR version. There are two sets of MOD results below... one with the state engine left from after the XOR, and one with a cleanly reseeded state engine.

#lang racket
;; Imperative version: Translation of C
;; Vigenère: Translation of Pascal
(module+ test (require tests/eli-tester))
 
;; ---------------------------------------------------------------------------------------------------
;; standard.h: Standard definitions and types, Bob Jenkins
(define UB4MAXVAL #xffffffff)
(define-syntax-rule (bit target mask) (bitwise-and target mask))
;; C-like operators
(define-syntax-rule (u4-truncate x) (bit x UB4MAXVAL))
(define-syntax-rule (u4<< a b) (u4-truncate (arithmetic-shift a b)))
(define-syntax-rule (u4>> a b) (u4-truncate (arithmetic-shift a (- b))))
(define-syntax-rule (_++ i) (let ((rv i)) (set! i (u4-truncate (add1 i))) rv))
(define-syntax-rule (u4+= a b) (begin (set! a (u4-truncate (+ a b))) a))
(define-syntax-rule (^= a b) (begin (set! a (u4-truncate (bitwise-xor a b))) a))
 
;; ---------------------------------------------------------------------------------------------------
;; rand.h: definitions for a random number generator
(define RANDSIZL 8)
(define RANDSIZ (u4<< 1 RANDSIZL))
(define RANDSIZ-1 (sub1 RANDSIZ))
 
(struct randctx
(cnt
rsl ; RANDSIZ*4 bytes (makes u4's)
mem ; RANDSIZ*4 bytes (makes u4's)
a b c) #:mutable)
 
(define (new-randctx)
(randctx 0 (make-bytes (* 4 RANDSIZ) 0) (make-bytes (* 4 RANDSIZ) 0) 0 0 0))
 
(define (bytes->hex-string B (start 0) (end #f) #:join (join "") #:show-bytes? (show-bytes? #f))
(define hexes
(for/list ((b (in-bytes B start end)))
(~a (number->string b 16) #:width 2 #:align 'right #:pad-string "0")))
(string-join
(append hexes (if show-bytes?
(list " \"" (bytes->string/utf-8 B #f start (or end (bytes-length B))) "\"")
null))
join))
 
(define format-randctx
(match-lambda
[(randctx C (app bytes->hex-string R) (app bytes->hex-string M) a b c)
(format "randctx: cnt:~a~%rsl:~s~%mem:~s~%a:~a b:~a c:~a" C R M a b c)]))
 
(define be? (system-big-endian?))
 
(define (bytes->u4 ary idx)
(integer-bytes->integer ary #f be? (* idx 4) (* (add1 idx) 4)))
 
(define (u4->bytes! ary idx v)
(integer->integer-bytes (bit v UB4MAXVAL) 4 #f be? ary (* idx 4)))
 
;; ---------------------------------------------------------------------------------------------------
;; rand.c: "By Bob Jenkins. My random number generator, ISAAC. Public Domain."
(define (ind mm x)
(define idx (bitwise-and x (u4<< RANDSIZ-1 2)))
(integer-bytes->integer mm #f be? idx (+ idx 4)))
 
(define (isaac C)
(define M (randctx-mem C))
(define R (randctx-rsl C))
(define mm 0)
(define r 0)
(define-syntax-rule (rng-step mix)
(begin
(define x (bytes->u4 M m))
(set! a (u4-truncate (+ (bitwise-xor a mix) (bytes->u4 M (_++ m2)))))
(define y (+ (ind M x) a b))
(u4->bytes! M (_++ m) y)
(set! b (u4-truncate (+ (ind M (u4>> y RANDSIZL)) x)))
(u4->bytes! R (_++ r) b)))
 
(define a (randctx-a C))
 
(set-randctx-c! C (add1 (randctx-c C)))
 
(define b (u4-truncate (+ (randctx-b C) (randctx-c C))))
 
(define m mm)
(define m2 (+ m (/ RANDSIZ 2)))
(define mend m2)
 
(define-syntax-rule (4-step-loop variant)
(let loop ()
(when (< variant mend)
(rng-step (u4<< a 13)) (rng-step (u4>> a 6))
(rng-step (u4<< a 2)) (rng-step (u4>> a 16))
(loop))))
 
(4-step-loop m)
(set! m2 mm)
(4-step-loop m2)
 
(set-randctx-b! C b)
(set-randctx-a! C a))
 
;; dot infix notation because I'm too lazy to move the operators left!
(define-syntax-rule (mix-line<< A B N D C)
(begin (A . ^= . (B . u4<< . N)) (D . u4+= . A) (B . u4+= . C)))
(define-syntax-rule (mix-line>> A B N D C)
(begin (A . ^= . (B . u4>> . N)) (D . u4+= . A) (B . u4+= . C)))
 
(define-syntax-rule (mix a b c d e f g h)
(begin (mix-line<< a b 11 d c) (mix-line>> b c 2 e d)
(mix-line<< c d 8 f e) (mix-line>> d e 16 g f)
(mix-line<< e f 10 h g) (mix-line>> f g 4 a h)
(mix-line<< g h 8 b a) (mix-line>> h a 9 c b)))
 
;; if (flag==TRUE), then use the contents of randrsl[] to initialize mm[].
(define (rand-init C flag?)
(set-randctx-a! C 0)
(set-randctx-b! C 0)
(set-randctx-c! C 0)
 
 ;; seed-ctx should set these up (with the seed!):
 ;; (set-ctx-rsl! C (make-bytes (* 4 RANDSIZ) 0))
 ;; (set-ctx-mem! C (make-bytes (* 4 RANDSIZ) 0))
(define R (randctx-rsl C))
(define M (randctx-mem C))
 
(define φ #x9e3779b9) ; the golden ratio
(match-define (list a b c d e f g h) (make-list 8 φ))
 
(for ((_ 4)) (mix a b c d e f g h)) ; scramble it
 
(define-syntax-rule (mix-and-assign i M2)
(begin
(mix a b c d e f g h)
(u4->bytes! M2 (+ i 0) a) (u4->bytes! M2 (+ i 1) b)
(u4->bytes! M2 (+ i 2) c) (u4->bytes! M2 (+ i 3) d)
(u4->bytes! M2 (+ i 4) e) (u4->bytes! M2 (+ i 5) f)
(u4->bytes! M2 (+ i 6) g) (u4->bytes! M2 (+ i 7) h)))
 
(define-syntax-rule (mix-with-mem M1 M2)
(for ((i (in-range 0 RANDSIZ 8)))
(a . u4+= . (bytes->u4 M1 (+ i 0))) (b . u4+= . (bytes->u4 M1 (+ i 1)))
(c . u4+= . (bytes->u4 M1 (+ i 2))) (d . u4+= . (bytes->u4 M1 (+ i 3)))
(e . u4+= . (bytes->u4 M1 (+ i 4))) (f . u4+= . (bytes->u4 M1 (+ i 5)))
(g . u4+= . (bytes->u4 M1 (+ i 6))) (h . u4+= . (bytes->u4 M1 (+ i 7)))
(mix-and-assign i M2)))
 
(cond
[flag? ; initialize using the contents of r[] as the seed
(mix-with-mem R M)
(mix-with-mem M M)] ; do a second pass to make all of the seed affect all of m
[else ; fill in m[] with messy stuff
(for ((i (in-range 0 RANDSIZ 8))) (mix-and-assign i M))])
 
(isaac C)  ; fill in the first set of results
(set-randctx-cnt! C 0)) ; prepare to use the first set of results
 
(define (seed-ctx C key #:flag? (flag? #t))
(bytes-fill! (randctx-mem C) 0)
(define R (randctx-rsl C))
(bytes-fill! (randctx-rsl C) 0)
(for ((k (in-bytes key)) (i (in-range (quotient (bytes-length R) 4)))) (u4->bytes! R i k))
(rand-init C flag?))
 
;; Get a random 32-bit value 0..MAXINT
(define (i-random C)
(define cnt (randctx-cnt C))
(define r (bytes->u4 (randctx-rsl C) cnt))
(define cnt+1 (add1 cnt))
(cond [(>= cnt+1 RANDSIZ) (isaac C) (set-randctx-cnt! C 0)]
[else (set-randctx-cnt! C cnt+1)])
r)
 
;; Get a random character in printable ASCII range
(define ((i-rand-a C))
(+ 32 (modulo (i-random C) 95)))
 
(define (Vernham rnd-fn msg)
(define gsm (make-bytes (bytes-length msg)))
(for ((i (in-naturals)) (m (in-bytes msg)))
(define r (rnd-fn))
(define b (bitwise-xor m r))
(bytes-set! gsm i b))
gsm)
 
;; Get position of the letter in chosen alphabet
;; Caesar-shift a character <shift> places: Generalized Vigenere
(define ((Caesar mod-n start) encrypt? shift ch)
(define (letter-num letter/byte)
(- letter/byte (char->integer start)))
 
(define shift-fn (if encrypt? + -))
(+ (char->integer start) (modulo (shift-fn (letter-num ch) shift) mod-n)))
 
;; Vigenère mod 95 encryption & decryption. Output: bytes
(define Vigenère-Caeser (Caesar 95 #\space))
(define (Vigenère encrypt? rand-fn msg)
(list->bytes
(for/list ((b (in-bytes msg)))
(Vigenère-Caeser encrypt? (rand-fn) b))))
 
{module+ main
(define message #"a Top Secret secret")
(define key #"this is my secret key")
(define C (new-randctx))
(seed-ctx C key)
(define vern.msg (Vernham (i-rand-a C) message))
 ;; Pascal doesn't reset the context betwen XOR and MOD
 ;; (seed-ctx C key)
(define vigen.msg (Vigenère #t (i-rand-a C) message))
(seed-ctx C key)
(define vern2.msg (Vernham (i-rand-a C) vern.msg))
 ;; Pascal doesn't reset the context betwen XOR and MOD
 ;; (seed-ctx C key)
(define unvigen.msg (Vigenère #f (i-rand-a C) vigen.msg))
 ;; This is what MOD looks like from the context as seeded with key
(seed-ctx C key)
(define vigen-at-seed.msg (Vigenère #t (i-rand-a C) message))
(seed-ctx C key)
(define unvigen-at-seed.msg (Vigenère #f (i-rand-a C) vigen-at-seed.msg))
 
(printf #<<EOS
Message: [~a]
Key: [~a]
 
< context reseeded
Vernham (XOR): [~a]
Vigenère (MOD): [~a]
 
< context reseeded
Vernham (XOR(XOR)): [~a]
Vigenère (-MOD): [~a]
 
< context reseeded (different to Pascal Vigenère encryption)
Vigenère (MOD): [~a]
< context reseeded
Vigenère (-MOD): [~a]
EOS
message
key
(bytes->hex-string vern.msg)
(bytes->hex-string vigen.msg #:show-bytes? #t)
(bytes->hex-string vern2.msg #:show-bytes? #t)
(bytes->hex-string unvigen.msg #:show-bytes? #t)
(bytes->hex-string vigen-at-seed.msg #:show-bytes? #t)
(bytes->hex-string unvigen-at-seed.msg #:show-bytes? #t)
)}
 
{module+ test
 ;; "If the initial internal state is all zero, after ten calls the values of aa, bb, and cc in
 ;; hexadecimal will be d4d3f473, 902c0691, and 0000000a."
(let ()
(define C (new-randctx))
(for ((_ 10)) (isaac C))
(test (randctx-a C) => #xd4d3f473
(randctx-b C) => #x902c0691
(randctx-c C) => 10))
}
Output:
Message:            [a Top Secret secret]
Key:                [this is my secret key]

                    < context reseeded
Vernham (XOR):      [1c0636190b1260233b35125f1e1d0e2f4c5422]
Vigenère (MOD):     [734270227d36772a783b4f2a5f206266236978 "sBp"}6w*x;O*_ bf#ix"]

                    < context reseeded
Vernham (XOR(XOR)): [6120546f702053656372657420736563726574 "a Top Secret secret"]
Vigenère (-MOD):    [6120546f702053656372657420736563726574 "a Top Secret secret"]

                    < context reseeded (different to Pascal Vigenère encryption)
Vigenère (MOD):     [204657272d52274c5c5a7d405e23715051376b " FW'-R'L\Z}@^#qPQ7k"]
                    < context reseeded
Vigenère (-MOD):    [6120546f702053656372657420736563726574 "a Top Secret secret"]

REXX[edit]

version 1[edit]

/* REXX ---------------------------------------------------------------
* 24.07.2014 Walter Pachl translated from Pascal
* extend with decryption (following Pascal)
* 25.07.2014 WP changed i+=8 to I=I+8 (courtesy GS)
* 26.07-2014 WP removed extraneous semicolons
*--------------------------------------------------------------------*/

Numeric Digits 32
aa=0
bb=0
cc=0
mm.=0
randcnt=0
randrsl.=0
msg='a Top Secret secret'
key='this is my secret key'
iMode='iEncrypt'
 
Call iSeed key,1 /* 1) seed ISAAC with the key */
xctx=Vernam(msg) /* 2) Vernam XOR encryption */
mode='iEncrypt'
mctx=Vigenere(msg,mode) /* 3) MOD encryption */
Call iSeed key,1
xptx=Vernam(xctx) /* a) XOR (Vernam) */
mode='iDecrypt'
mptx=Vigenere(mctx,mode) /* b) MOD (Vigenere) */
/* program output */
Say 'Message: 'msg
Say 'Key  : 'key
Say 'XOR  : 'c2x(xctx)
Say 'MOD  : 'c2x(mctx)
Say 'XOR dcr: 'xptx
Say 'MOD dcr: 'mptx
Exit
 
isaac: Procedure Expose mm. aa bb cc randrsl. randcnt
cc=add(cc,1)
bb=add(bb,cc)
Do i=0 To 255
x=mm.i
im4=i//4
Select
When im4=0 Then aa=xor(aa,shl(aa,13))
When im4=1 Then aa=xor(aa,shr(aa, 6))
When im4=2 Then aa=xor(aa,shl(aa, 2))
When im4=3 Then aa=xor(aa,shr(aa,16))
End
z=(i+128)//256
aa=add(mm.z,aa)
z=shr(x,2)//256
y=add(mm.z,aa,bb)
mm.i=y
z=shr(y,10)//256
bb=add(mm.z,x)
randrsl.i=bb
End
randcnt=0
Return
 
mix: Procedure Expose a b c d e f g h mm. aa bb cc randrsl. randcnt
a=xor(a,shl(b,11)); d=add(d,a); b=add(b,c)
b=xor(b,shr(c, 2)); e=add(e,b); c=add(c,d)
c=xor(c,shl(d, 8)); f=add(f,c); d=add(d,e)
d=xor(d,shr(e,16)); g=add(g,d); e=add(e,f)
e=xor(e,shl(f,10)); h=add(h,e); f=add(f,g)
f=xor(f,shr(g, 4)); a=add(a,f); g=add(g,h)
g=xor(g,shl(h, 8)); b=add(b,g); h=add(h,a)
h=xor(h,shr(a, 9)); c=add(c,h); a=add(a,b)
Return
 
iRandInit: Procedure Expose mm. randrsl. randcnt
Parse Arg flag
aa=0; bb=0; cc=0
a= 2654435769 /* $9e3779b9; // the golden ratio */
 
b=a; c=a; d=a; e=a; f=a; g=a; h=a
 
do i=0 TO 3
Call mix
End
 
i=0
do until i>255 /* fill in mm[] with messy stuff */
IF flag THEN Do /* use all the information in the seed */
Call setix
a=add(a,randrsl.i); b=add(b,randrsl.i1)
c=add(c,randrsl.i2); d=add(d,randrsl.i3)
e=add(e,randrsl.i4); f=add(f,randrsl.i5)
g=add(g,randrsl.i6); h=add(h,randrsl.i7)
End
Call mix
mm.i=a; mm.i1=b; mm.i2=c; mm.i3=d
mm.i4=e; mm.i5=f; mm.i6=g; mm.i7=h
i=i+8
End
 
IF flag THEN Do /* do a second pass to make all of the seed affect all of mm */
i=0
do until i>255 /* fill in mm[] with messy stuff */
Call setix
a=add(a,mm.i); b=add(b,mm.i1); c=add(c,mm.i2); d=add(d,mm.i3)
e=add(e,mm.i4); f=add(f,mm.i5); g=add(g,mm.i6); h=add(h,mm.i7)
Call mix
mm.i=a; mm.i1=b; mm.i2=c; mm.i3=d
mm.i4=e; mm.i5=f; mm.i6=g; mm.i7=h
i=i+8
End
End
Call isaac /* fill in the first set of results */
randcnt=0; /* prepare to use the first set of results */
Return
 
iseed: Procedure Expose aa bb cc randcnt randrsl. mm.
/*---------------------------------------------------------------------
* Seed ISAAC with a given string.
* The string can be any size. The first 256 values will be used.
*--------------------------------------------------------------------*/

Parse Arg seed,flag
mm.=0
m=Length(seed)-1
Do i=0 TO 255
IF i>m THEN /* in case seed has less than 256 elements */
randrsl.i=0
ELSE
randrsl.i=c2d(substr(seed,i+1,1))
end
Call iRandInit flag /* initialize ISAAC with seed */
Return
 
iRandom: Procedure Expose aa bb cc randcnt randrsl. mm.
/* Get a random 32-bit value 0..MAXINT */
iRandom=randrsl.randcnt
randcnt=randcnt+1
If randcnt>255 Then Do
Call isaac
randcnt=0
End
Return irandom
 
iRandA: Procedure Expose aa bb cc randcnt randrsl. mm.
/* Get a random character in printable ASCII range */
iRandA=iRandom()//95+32
Return iRandA
 
xor: Procedure Expose aa bb cc randcnt randrsl. mm.
Parse Arg a,b
ac=d2c(a,4)
bc=d2c(b,4)
res=c2d(bitxor(ac,bc))
return res//4294967296
 
Vernam: Procedure Expose aa bb cc randcnt randrsl. mm.
/* XOR encrypt on random stream. Output: string of hex chars */
Parse Arg msg
Vernam=''
Do i=1 to length(msg)
Vernam=Vernam||d2c(xor(iRandA(),c2d(substr(msg,i,1))))
End
Return Vernam
 
letternum: Procedure Expose aa bb cc randcnt randrsl. mm.
/* Get position of the letter in chosen alphabet */
Parse Arg letter,start
letternum=c2d(letter)-c2d(start)
Return letternum
 
Caesar: Procedure Expose aa bb cc randcnt randrsl. mm.
/* Caesar-shift a character <shift> places: Generalized Vigenere */
Parse Arg m,ch,shift,modulo,start
IF m='iDecrypt' TheN shift=-shift
n=letternum(ch,start)+shift
n=n//modulo
IF n<0 Then n=n+modulo
Caesar=d2c(c2d(start)+n)
Return Caesar
 
Vigenere: Procedure Expose aa bb cc randcnt randrsl. mm.
/* Vigenere mod 95 encryption. Output: string of hex chars */
Parse Arg msg,m
Vigenere=''
Do i=1 to length(msg)
Vigenere=Vigenere||Caesar(m,substr(msg,i,1),iRandA(),95,' ')
End
Return Vigenere
 
shl: Procedure
res=arg(1)*(2**arg(2))
return res//4294967296
 
shr: Procedure
res=arg(1)%(2**arg(2))
return res//4294967296
 
setix:
i1=i+1
i2=i+2
i3=i+3
i4=i+4
i5=i+5
i6=i+6
i7=i+7
Return
 
add: Procedure
/* add argumemnts modulo 4294967296 */
res=arg(1)+arg(2)
If arg(3)<>'' Then
res=res+arg(3)
return res//4294967296
Output:
Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1C0636190B1260233B35125F1E1D0E2F4C5422
MOD    : 734270227D36772A783B4F2A5F206266236978
XOR dcr: a Top Secret secret
MOD dcr: a Top Secret secret

version 2[edit]

This can be used to ecrypt a file and thereafter decrypt it.

/* REXX ---------------------------------------------------------------
* 25.07.2014 Walter Pachl framing version 1 for processing a file
*--------------------------------------------------------------------*/

Parse Arg fid
select
When fid='' Then
fid='test_file.txt'
When fid='?' Then Do
Say 'rexx iscf file prompts you for a key,'
Say 'encrypts file into fn.enc'
Say 'and decrypts fn.enc into fn.dec'
Exit
End
Otherwise
Nop
End
Say 'Please enter a key'
Parse Pull key
enc=fn(fid)'.enc' ; 'erase' enc
dec=fn(fid)'.dec' ; 'erase' dec
Do While lines(fid)>0
l=linein(fid)
Call lineout enc,iscx(l,key,'e')
End
Call lineout enc
Do While lines(enc)>0
l=linein(enc)
Call lineout dec,iscx(l,key,'d')
End
Call lineout dec
Say 'original:'
'type' fid
Say 'encrypted:'
'type' enc
Say 'decrypted:'
'type' dec
Exit
iscx: Procedure
/* REXX ---------------------------------------------------------------
* 24.07.2014 Walter Pachl translated from Pascal
* extend with decoding
*--------------------------------------------------------------------*/

Numeric Digits 32
aa=0
bb=0
cc=0
mm.=0
randcnt=0
randrsl.=0
Parse Arg msg,key,mode
 
Call iSeed key,1 /* 1) seed ISAAC with the key */
If mode='e' Then
mode='iEncrypt'
Else
mode='iDecrypt'
mctx=Vigenere(msg,mode) /* 3) MOD encryption */
Return mctx
 
isaac: Procedure Expose mm. aa bb cc randrsl. randcnt
cc=add(cc,1)
bb=add(bb,cc)
Do i=0 To 255
x=mm.i
im4=i//4
Select
When im4=0 Then aa=xor(aa,shl(aa,13))
When im4=1 Then aa=xor(aa,shr(aa, 6))
When im4=2 Then aa=xor(aa,shl(aa, 2))
When im4=3 Then aa=xor(aa,shr(aa,16))
End
z=(i+128)//256
aa=add(mm.z,aa)
z=shr(x,2)//256
y=add(mm.z,aa,bb)
mm.i=y
z=shr(y,10)//256
bb=add(mm.z,x)
randrsl.i=bb
End
randcnt=0
Return
 
mix: Procedure Expose a b c d e f g h mm. aa bb cc randrsl. randcnt
a=xor(a,shl(b,11)); d=add(d,a); b=add(b,c)
b=xor(b,shr(c, 2)); e=add(e,b); c=add(c,d)
c=xor(c,shl(d, 8)); f=add(f,c); d=add(d,e)
d=xor(d,shr(e,16)); g=add(g,d); e=add(e,f)
e=xor(e,shl(f,10)); h=add(h,e); f=add(f,g)
f=xor(f,shr(g, 4)); a=add(a,f); g=add(g,h)
g=xor(g,shl(h, 8)); b=add(b,g); h=add(h,a)
h=xor(h,shr(a, 9)); c=add(c,h); a=add(a,b)
Return
 
iRandInit: Procedure Expose mm. randrsl. randcnt
Parse Arg flag
aa=0; bb=0; cc=0
a= 2654435769 /* $9e3779b9; // the golden ratio */
 
b=a; c=a; d=a; e=a; f=a; g=a; h=a
 
do i=0 TO 3
Call mix
End
 
i=0
do until i>255 /* fill in mm[] with messy stuff */
IF flag THEN Do /* use all the information in the seed */
Call setix
a=add(a,randrsl.i); b=add(b,randrsl.i1)
c=add(c,randrsl.i2); d=add(d,randrsl.i3)
e=add(e,randrsl.i4); f=add(f,randrsl.i5)
g=add(g,randrsl.i6); h=add(h,randrsl.i7)
End
Call mix
mm.i=a; mm.i1=b; mm.i2=c; mm.i3=d
mm.i4=e; mm.i5=f; mm.i6=g; mm.i7=h
i+=8
End
 
IF flag THEN Do /* do a second pass to make all of the seed affect all of mm */
i=0
do until i>255 /* fill in mm[] with messy stuff */
Call setix
a=add(a,mm.i); b=add(b,mm.i1); c=add(c,mm.i2); d=add(d,mm.i3)
e=add(e,mm.i4); f=add(f,mm.i5); g=add(g,mm.i6); h=add(h,mm.i7)
Call mix
mm.i=a; mm.i1=b; mm.i2=c; mm.i3=d
mm.i4=e; mm.i5=f; mm.i6=g; mm.i7=h
i+=8
End
End
Call isaac /* fill in the first set of results */
randcnt=0; /* prepare to use the first set of results */
Return
 
iseed: Procedure Expose aa bb cc randcnt randrsl. mm.
/*---------------------------------------------------------------------
* Seed ISAAC with a given string.
* The string can be any size. The first 256 values will be used.
*--------------------------------------------------------------------*/

Parse Arg seed,flag
mm.=0
m=Length(seed)-1
Do i=0 TO 255
IF i>m THEN /* in case seed has less than 256 elements */
randrsl.i=0
ELSE
randrsl.i=c2d(substr(seed,i+1,1))
end
Call iRandInit flag /* initialize ISAAC with seed */
Return
 
iRandom: Procedure Expose aa bb cc randcnt randrsl. mm.
/* Get a random 32-bit value 0..MAXINT */
iRandom=randrsl.randcnt
randcnt=randcnt+1
If randcnt>255 Then Do
Call isaac
randcnt=0
End
Return irandom
 
iRandA: Procedure Expose aa bb cc randcnt randrsl. mm.
/* Get a random character in printable ASCII range */
iRandA=iRandom()//95+32
Return iRandA
 
xor: Procedure Expose aa bb cc randcnt randrsl. mm.
Parse Arg a,b
ac=d2c(a,4)
bc=d2c(b,4)
res=c2d(bitxor(ac,bc))
return res//4294967296
 
Vernam: Procedure Expose aa bb cc randcnt randrsl. mm.
/* XOR encrypt on random stream. Output: string of hex chars */
Parse Arg msg
Vernam=''
Do i=1 to length(msg)
Vernam=Vernam||d2c(xor(iRandA(),c2d(substr(msg,i,1))))
End
Return Vernam
 
letternum: Procedure Expose aa bb cc randcnt randrsl. mm.
/* Get position of the letter in chosen alphabet */
Parse Arg letter,start
letternum=c2d(letter)-c2d(start)
Return letternum
 
Caesar: Procedure Expose aa bb cc randcnt randrsl. mm.
/* Caesar-shift a character <shift> places: Generalized Vigenere */
Parse Arg m,ch,shift,modulo,start
IF m='iDecrypt' TheN shift=-shift
n=letternum(ch,start)+shift
n=n//modulo
IF n<0 Then n=n+modulo
Caesar=d2c(c2d(start)+n)
Return Caesar
 
Vigenere: Procedure Expose aa bb cc randcnt randrsl. mm.
/* Vigenere mod 95 encryption. Output: string of hex chars */
Parse Arg msg,m
Vigenere=''
Do i=1 to length(msg)
Vigenere=Vigenere||Caesar(m,substr(msg,i,1),iRandA(),95,' ')
End
Return Vigenere
 
shl: Procedure
res=arg(1)*(2**arg(2))
return res//4294967296
 
shr: Procedure
res=arg(1)%(2**arg(2))
return res//4294967296
 
setix:
i1=i+1
i2=i+2
i3=i+3
i4=i+4
i5=i+5
i6=i+6
i7=i+7
Return
 
add: Procedure
/* add argumemnts modulo 4294967296 */
res=arg(1)+arg(2)
If arg(3)<>'' Then
res=res+arg(3)
return res//4294967296
 
fn: Procedure
/* REXX */
parse Arg fid
Parse Var fid fn '.' ft
Return fn
Output:
Please enter a key
original:
This is a little test file
that shows my encryption
encrypted:
KrG"3n(sr_5=OiziiWnJ.`5RY=
kr?#3x|c)SHATtsrMU#G.J>W
decrypted:
This is a little test file
that shows my encryption

Sidef[edit]

Translation of: Perl
require('Math::Random::ISAAC')
 
func xor_isaac(key, msg) {
var rng = %O<Math::Random::ISAAC>.new(unpack('C*', key))
 
msg.chars»ord()» \
-> »^« 256.of{ rng.irand % 95 + 32 }.last(msg.len).flip \
-> «%« '%02X' -> join
}
 
var msg = 'a Top Secret secret'
var key = 'this is my secret key'
 
var enc = xor_isaac(key, msg)
var dec = xor_isaac(key, pack('H*', enc))
 
say "Message: #{msg}"
say "Key  : #{key}"
say "XOR  : #{enc}"
say "XOR dcr: #{pack('H*', dec)}"
Output:
Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1C0636190B1260233B35125F1E1D0E2F4C5422
XOR dcr: a Top Secret secret

Tcl[edit]

Works with: Tcl version 8.6
Translation of: Go
package require Tcl 8.6
 
oo::class create ISAAC {
variable aa bb cc mm randrsl randcnt
 
constructor {seed} {
namespace eval tcl {
namespace eval mathfunc {
proc mm {idx} {
upvar 1 mm list
lindex $list [expr {$idx % [llength $list]}]
}
proc clamp {value} {
expr {$value & 0xFFFFFFFF}
}
}
}
proc mix1 {i v} {
upvar 1 a a
lset a $i [expr {clamp([lindex $a $i] ^ $v)}]
lset a [set idx [expr {($i+3)%8}]] \
[expr {clamp([lindex $a $idx] + [lindex $a $i])}]
lset a [set idx [expr {($i+1)%8}]] \
[expr {clamp([lindex $a $idx] + [lindex $a [expr {($i+2)%8}]])}]
}
 
binary scan $seed[string repeat \u0000 256] c256 randrsl
set mm [lrepeat 256 0]
set randcnt [set aa [set bb [set cc 0]]]
 
set a [lrepeat 8 0x9e3779b9]
foreach i {1 2 3 4} {
mix1 0 [expr {[lindex $a 1] << 11}]
mix1 1 [expr {[lindex $a 2] >> 2}]
mix1 2 [expr {[lindex $a 3] << 8}]
mix1 3 [expr {[lindex $a 4] >> 16}]
mix1 4 [expr {[lindex $a 5] << 10}]
mix1 5 [expr {[lindex $a 6] >> 4}]
mix1 6 [expr {[lindex $a 7] << 8}]
mix1 7 [expr {[lindex $a 0] >> 9}]
}
for {set i 0} {$i < 256} {incr i 8} {
set a [lmap av $a bv [lrange $randrsl $i [expr {$i+7}]] {
expr {clamp($av + $bv)}
}]
mix1 0 [expr {[lindex $a 1] << 11}]
mix1 1 [expr {[lindex $a 2] >> 2}]
mix1 2 [expr {[lindex $a 3] << 8}]
mix1 3 [expr {[lindex $a 4] >> 16}]
mix1 4 [expr {[lindex $a 5] << 10}]
mix1 5 [expr {[lindex $a 6] >> 4}]
mix1 6 [expr {[lindex $a 7] << 8}]
mix1 7 [expr {[lindex $a 0] >> 9}]
for {set j 0} {$j < 8} {incr j} {
lset mm [expr {$i+$j}] [lindex $a $j]
}
}
for {set i 0} {$i < 256} {incr i 8} {
set a [lmap av $a bv [lrange $mm $i [expr {$i+7}]] {
expr {clamp($av + $bv)}
}]
mix1 0 [expr {[lindex $a 1] << 11}]
mix1 1 [expr {[lindex $a 2] >> 2}]
mix1 2 [expr {[lindex $a 3] << 8}]
mix1 3 [expr {[lindex $a 4] >> 16}]
mix1 4 [expr {[lindex $a 5] << 10}]
mix1 5 [expr {[lindex $a 6] >> 4}]
mix1 6 [expr {[lindex $a 7] << 8}]
mix1 7 [expr {[lindex $a 0] >> 9}]
for {set j 0} {$j < 8} {incr j} {
lset mm [expr {$i+$j}] [lindex $a $j]
}
}
my Step
}
 
method Step {} {
incr bb [incr cc]
set i -1
foreach x $mm {
set shift [lindex {13 -6 2 -16} [expr {[incr i] % 4}]]
set aa [expr {$aa ^ ($shift>0 ? $aa<<$shift : $aa>>-$shift)}]
set aa [expr {clamp($aa + mm($i+128))}]
set y [expr {clamp(mm($x>>2) + $aa + $bb)}]
lset mm $i $y
set bb [expr {clamp(mm($y>>10) + $x)}]
lset randrsl $i $bb
}
}
 
method random {} {
set r [lindex $randrsl $randcnt]
if {[incr randcnt] == 256} {
my Step
set randcnt 0
}
return $r
}
 
method RandA {} {
expr {([my random] % 95) + 32}
}
method vernam {msg} {
binary scan $msg c* b
for {set i 0} {$i < [llength $b]} {incr i} {
lset b $i [expr {[lindex $b $i] & 255 ^ [my RandA]}]
}
return [binary encode hex [binary format c* $b]]
}
}

Demonstrating:

set key "this is my secret key"
set msg "a Top Secret secret"
ISAAC create demo $key
puts "Message: $msg"
puts "Key  : $key"
puts "XOR  : [demo vernam $msg]"
Output:
Message: a Top Secret secret
Key    : this is my secret key
XOR    : 1c0636190b1260233b35125f1e1d0e2f4c5422