1 // Random number generator - requires a PRNG backend, e.g. prng4.js
3 // For best results, put code like
4 // <body onClick='rng_seed_time();' onKeyPress='rng_seed_time();'>
5 // in your main HTML document.
11 // Mix in a 32-bit integer into the pool
12 function rng_seed_int(x) {
13 rng_pool[rng_pptr++] ^= x & 255;
14 rng_pool[rng_pptr++] ^= (x >> 8) & 255;
15 rng_pool[rng_pptr++] ^= (x >> 16) & 255;
16 rng_pool[rng_pptr++] ^= (x >> 24) & 255;
17 if(rng_pptr >= rng_psize) rng_pptr -= rng_psize;
20 // Mix in the current time (w/milliseconds) into the pool
21 function rng_seed_time() {
22 rng_seed_int(new Date().getTime());
25 // Initialize the pool with junk if needed.
26 if(rng_pool == null) {
27 rng_pool = new Array();
30 if(navigator.appName == "Netscape" && navigator.appVersion < "5" && window.crypto) {
31 // Extract entropy (256 bits) from NS4 RNG if available
32 var z = window.crypto.random(32);
33 for(t = 0; t < z.length; ++t)
34 rng_pool[rng_pptr++] = z.charCodeAt(t) & 255;
36 while(rng_pptr < rng_psize) { // extract some randomness from Math.random()
37 t = Math.floor(65536 * Math.random());
38 rng_pool[rng_pptr++] = t >>> 8;
39 rng_pool[rng_pptr++] = t & 255;
43 //rng_seed_int(window.screenX);
44 //rng_seed_int(window.screenY);
47 function rng_get_byte() {
48 if(rng_state == null) {
50 rng_state = prng_newstate();
51 rng_state.init(rng_pool);
52 for(rng_pptr = 0; rng_pptr < rng_pool.length; ++rng_pptr)
53 rng_pool[rng_pptr] = 0;
57 // TODO: allow reseeding after first request
58 return rng_state.next();
61 function rng_get_bytes(ba) {
63 for(i = 0; i < ba.length; ++i) ba[i] = rng_get_byte();
66 function SecureRandom() {}
68 SecureRandom.prototype.nextBytes = rng_get_bytes;