// 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(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;
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