ig-trader
Version:
A client to programmatically spreadbet with IG
84 lines (71 loc) • 2.72 kB
JavaScript
// Author: Tom Wu
// tjw@cs.Stanford.EDU
// 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 Arcfour = require('./prng4');
// 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;
function SecureRandom() {
this.rng_state;
this.rng_pool;
this.rng_pptr;
// Mix in a 32-bit integer into the pool
this.rng_seed_int = function(x) {
this.rng_pool[this.rng_pptr++] ^= x & 255;
this.rng_pool[this.rng_pptr++] ^= (x >> 8) & 255;
this.rng_pool[this.rng_pptr++] ^= (x >> 16) & 255;
this.rng_pool[this.rng_pptr++] ^= (x >> 24) & 255;
if(this.rng_pptr >= rng_psize) this.rng_pptr -= rng_psize;
}
// Mix in the current time (w/milliseconds) into the pool
this.rng_seed_time = function() {
this.rng_seed_int(new Date().getTime());
}
// Initialize the pool with junk if needed.
if(this.rng_pool == null) {
this.rng_pool = new Array();
this.rng_pptr = 0;
var 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)
this.rng_pool[this.rng_pptr++] = z.charCodeAt(t) & 255;
}
while(this.rng_pptr < rng_psize) { // extract some randomness from Math.random()
t = Math.floor(65536 * Math.random());
this.rng_pool[this.rng_pptr++] = t >>> 8;
this.rng_pool[this.rng_pptr++] = t & 255;
}
this.rng_pptr = 0;
this.rng_seed_time();
//this.rng_seed_int(window.screenX);
//this.rng_seed_int(window.screenY);
}
this.rng_get_byte = function() {
if(this.rng_state == null) {
this.rng_seed_time();
this.rng_state = prng_newstate();
this.rng_state.init(this.rng_pool);
for(this.rng_pptr = 0; this.rng_pptr < this.rng_pool.length; ++this.rng_pptr)
this.rng_pool[this.rng_pptr] = 0;
this.rng_pptr = 0;
//this.rng_pool = null;
}
// TODO: allow reseeding after first request
return this.rng_state.next();
}
//public function
this.nextBytes = function(ba) {
var i;
for(i = 0; i < ba.length; ++i) ba[i] = this.rng_get_byte();
}
}
module.exports = SecureRandom;