adoc/rng.js

## rng.js
//http://www-cs-students.stanford.edu/~tjw/jsbn/prng.js
// prng4.js - uses Arcfour as a PRNG

function Arcfour() {
  this.i = 0;
  this.j = 0;
  this.S = new Array();
}

// Initialize arcfour context from key, an array of ints, each from [0..255]
function ARC4init(key) {
  var i, j, t;
  for(i = 0; i < 256; ++i)
    this.S[i] = i;
  j = 0;
  for(i = 0; i < 256; ++i) {
    j = (j + this.S[i] + key[i % key.length]) & 255;
    t = this.S[i];
    this.S[i] = this.S[j];
    this.S[j] = t;
  }
  this.i = 0;
  this.j = 0;
}

function ARC4next() {
  var t;
  this.i = (this.i + 1) & 255;
  this.j = (this.j + this.S[this.i]) & 255;
  t = this.S[this.i];
  this.S[this.i] = this.S[this.j];
  this.S[this.j] = t;
  return this.S[(t + this.S[this.i]) & 255];
}

Arcfour.prototype.init = ARC4init;
Arcfour.prototype.next = ARC4next;

// Plug in your RNG constructor here
function prng_newstate() {
  return new Arcfour();
}

// Pool size must be a multiple of 4 and greater than 32.
// An array of bytes the size of the pool will be passed to init()
var rng_psize = 256;


//http://www-cs-students.stanford.edu/~tjw/jsbn/rng.js
// Random number generator - requires a PRNG backend, e.g. prng4.js

// For best results, put code like
// <body onClick='rng_seed_time();' onKeyPress='rng_seed_time();'>
// in your main HTML document.

var rng_state;
var rng_pool;
var rng_pptr;

// Mix in a 32-bit integer into the pool
function rng_seed_int(x) {
  rng_pool[rng_pptr++] ^= x & 255;
  rng_pool[rng_pptr++] ^= (x >> 8) & 255;
  rng_pool[rng_pptr++] ^= (x >> 16) & 255;
  rng_pool[rng_pptr++] ^= (x >> 24) & 255;
  if(rng_pptr >= rng_psize) rng_pptr -= rng_psize;
}

// Mix in the current time (w/milliseconds) into the pool
function rng_seed_time() {
  rng_seed_int(new Date().getTime());
}

// Initialize the pool with junk if needed.
if(rng_pool == null) {
  rng_pool = new Array();
  rng_pptr = 0;
  var t;
  if(window.crypto && window.crypto.getRandomValues) {
    // Use webcrypto if available
    var ua = new Uint8Array(32);
    window.crypto.getRandomValues(ua);
    for(t = 0; t < 32; ++t)
      rng_pool[rng_pptr++] = ua[t];
  }
  if(navigator.appName == "Netscape" && navigator.appVersion < "5" && window.crypto) {
    // Extract entropy (256 bits) from NS4 RNG if available
    var z = window.crypto.random(32);
    for(t = 0; t < z.length; ++t)
      rng_pool[rng_pptr++] = z.charCodeAt(t) & 255;
  }
  while(rng_pptr < rng_psize) {  // extract some randomness from Math.random()
    t = Math.floor(65536 * Math.random());
    rng_pool[rng_pptr++] = t >>> 8;
    rng_pool[rng_pptr++] = t & 255;
  }
  rng_pptr = 0;
  rng_seed_time();
  //rng_seed_int(window.screenX);
  //rng_seed_int(window.screenY);
}

function rng_get_byte() {
  if(rng_state == null) {
    rng_seed_time();
    rng_state = prng_newstate();
    rng_state.init(rng_pool);
    for(rng_pptr = 0; rng_pptr < rng_pool.length; ++rng_pptr)
      rng_pool[rng_pptr] = 0;
    rng_pptr = 0;
    //rng_pool = null;
  }
  // TODO: allow reseeding after first request
  return rng_state.next();
}

function rng_get_bytes(ba) {
  var i;
  for(i = 0; i < ba.length; ++i) ba[i] = rng_get_byte();
}

function SecureRandom() {}

SecureRandom.prototype.nextBytes = rng_get_bytes;
	//http://www-cs-students.stanford.edu/~tjw/jsbn/prng.js
	// prng4.js - uses Arcfour as a PRNG

	function Arcfour() {
	this.i = 0;
	this.j = 0;
	this.S = new Array();
	}

	// Initialize arcfour context from key, an array of ints, each from [0..255]
	function ARC4init(key) {
	var i, j, t;
	for(i = 0; i < 256; ++i)
	this.S[i] = i;
	j = 0;
	for(i = 0; i < 256; ++i) {
	j = (j + this.S[i] + key[i % key.length]) & 255;
	t = this.S[i];
	this.S[i] = this.S[j];
	this.S[j] = t;
	}
	this.i = 0;
	this.j = 0;
	}

	function ARC4next() {
	var t;
	this.i = (this.i + 1) & 255;
	this.j = (this.j + this.S[this.i]) & 255;
	t = this.S[this.i];
	this.S[this.i] = this.S[this.j];
	this.S[this.j] = t;
	return this.S[(t + this.S[this.i]) & 255];
	}

	Arcfour.prototype.init = ARC4init;
	Arcfour.prototype.next = ARC4next;

	// Plug in your RNG constructor here
	function prng_newstate() {
	return new Arcfour();
	}

	// Pool size must be a multiple of 4 and greater than 32.
	// An array of bytes the size of the pool will be passed to init()
	var rng_psize = 256;


	//http://www-cs-students.stanford.edu/~tjw/jsbn/rng.js
	// Random number generator - requires a PRNG backend, e.g. prng4.js

	// For best results, put code like
	// <body onClick='rng_seed_time();' onKeyPress='rng_seed_time();'>
	// in your main HTML document.

	var rng_state;
	var rng_pool;
	var rng_pptr;

	// Mix in a 32-bit integer into the pool
	function rng_seed_int(x) {
	rng_pool[rng_pptr++] ^= x & 255;
	rng_pool[rng_pptr++] ^= (x >> 8) & 255;
	rng_pool[rng_pptr++] ^= (x >> 16) & 255;
	rng_pool[rng_pptr++] ^= (x >> 24) & 255;
	if(rng_pptr >= rng_psize) rng_pptr -= rng_psize;
	}

	// Mix in the current time (w/milliseconds) into the pool
	function rng_seed_time() {
	rng_seed_int(new Date().getTime());
	}

	// Initialize the pool with junk if needed.
	if(rng_pool == null) {
	rng_pool = new Array();
	rng_pptr = 0;
	var t;
	if(window.crypto && window.crypto.getRandomValues) {
	// Use webcrypto if available
	var ua = new Uint8Array(32);
	window.crypto.getRandomValues(ua);
	for(t = 0; t < 32; ++t)
	rng_pool[rng_pptr++] = ua[t];
	}
	if(navigator.appName == "Netscape" && navigator.appVersion < "5" && window.crypto) {
	// Extract entropy (256 bits) from NS4 RNG if available
	var z = window.crypto.random(32);
	for(t = 0; t < z.length; ++t)
	rng_pool[rng_pptr++] = z.charCodeAt(t) & 255;
	}
	while(rng_pptr < rng_psize) { // extract some randomness from Math.random()
	t = Math.floor(65536 * Math.random());
	rng_pool[rng_pptr++] = t >>> 8;
	rng_pool[rng_pptr++] = t & 255;
	}
	rng_pptr = 0;
	rng_seed_time();
	//rng_seed_int(window.screenX);
	//rng_seed_int(window.screenY);
	}

	function rng_get_byte() {
	if(rng_state == null) {
	rng_seed_time();
	rng_state = prng_newstate();
	rng_state.init(rng_pool);
	for(rng_pptr = 0; rng_pptr < rng_pool.length; ++rng_pptr)
	rng_pool[rng_pptr] = 0;
	rng_pptr = 0;
	//rng_pool = null;
	}
	// TODO: allow reseeding after first request
	return rng_state.next();
	}

	function rng_get_bytes(ba) {
	var i;
	for(i = 0; i < ba.length; ++i) ba[i] = rng_get_byte();
	}

	function SecureRandom() {}

	SecureRandom.prototype.nextBytes = rng_get_bytes;