69 lines
1.8 KiB
JavaScript
69 lines
1.8 KiB
JavaScript
// Random number generator - requires a PRNG backend, e.g. prng4.js
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// For best results, put code like
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// <body onClick='rng_seed_time();' onKeyPress='rng_seed_time();'>
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// in your main HTML document.
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var rng_state;
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var rng_pool;
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var rng_pptr;
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// Mix in a 32-bit integer into the pool
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function rng_seed_int(x) {
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rng_pool[rng_pptr++] ^= x & 255;
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rng_pool[rng_pptr++] ^= (x >> 8) & 255;
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rng_pool[rng_pptr++] ^= (x >> 16) & 255;
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rng_pool[rng_pptr++] ^= (x >> 24) & 255;
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if(rng_pptr >= rng_psize) rng_pptr -= rng_psize;
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}
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// Mix in the current time (w/milliseconds) into the pool
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function rng_seed_time() {
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rng_seed_int(new Date().getTime());
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}
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// Initialize the pool with junk if needed.
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if(rng_pool == null) {
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rng_pool = new Array();
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rng_pptr = 0;
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var t;
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if(navigator.appName == "Netscape" && navigator.appVersion < "5" && window.crypto) {
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// Extract entropy (256 bits) from NS4 RNG if available
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var z = window.crypto.random(32);
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for(t = 0; t < z.length; ++t)
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rng_pool[rng_pptr++] = z.charCodeAt(t) & 255;
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}
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while(rng_pptr < rng_psize) { // extract some randomness from Math.random()
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t = Math.floor(65536 * Math.random());
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rng_pool[rng_pptr++] = t >>> 8;
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rng_pool[rng_pptr++] = t & 255;
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}
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rng_pptr = 0;
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rng_seed_time();
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//rng_seed_int(window.screenX);
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//rng_seed_int(window.screenY);
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}
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function rng_get_byte() {
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if(rng_state == null) {
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rng_seed_time();
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rng_state = prng_newstate();
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rng_state.init(rng_pool);
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for(rng_pptr = 0; rng_pptr < rng_pool.length; ++rng_pptr)
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rng_pool[rng_pptr] = 0;
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rng_pptr = 0;
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//rng_pool = null;
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}
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// TODO: allow reseeding after first request
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return rng_state.next();
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}
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function rng_get_bytes(ba) {
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var i;
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for(i = 0; i < ba.length; ++i) ba[i] = rng_get_byte();
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}
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function SecureRandom() {}
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SecureRandom.prototype.nextBytes = rng_get_bytes;
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