// 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;