186 lines
No EOL
5.2 KiB
JavaScript
186 lines
No EOL
5.2 KiB
JavaScript
/*!
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* Random number generator with ArcFour PRNG
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*
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* NOTE: For best results, put code like
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* <body onclick='SecureRandom.seedTime();' onkeypress='SecureRandom.seedTime();'>
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* in your main HTML document.
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*
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* Copyright Tom Wu, bitaddress.org BSD License.
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* http://www-cs-students.stanford.edu/~tjw/jsbn/LICENSE
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*/
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(function () {
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// Constructor function of Global SecureRandom object
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var sr = window.SecureRandom = function () { };
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// Properties
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sr.state;
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sr.pool;
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sr.pptr;
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sr.poolCopyOnInit;
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// Pool size must be a multiple of 4 and greater than 32.
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// An array of bytes the size of the pool will be passed to init()
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sr.poolSize = 256;
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// --- object methods ---
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// public method
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// ba: byte array
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sr.prototype.nextBytes = function (ba) {
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var i;
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if (window.crypto && window.crypto.getRandomValues && window.Uint8Array) {
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try {
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var rvBytes = new Uint8Array(ba.length);
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window.crypto.getRandomValues(rvBytes);
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for (i = 0; i < ba.length; ++i)
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ba[i] = sr.getByte() ^ rvBytes[i];
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return;
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} catch (e) {
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alert(e);
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}
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}
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for (i = 0; i < ba.length; ++i) ba[i] = sr.getByte();
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};
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// --- static methods ---
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// Mix in the current time (w/milliseconds) into the pool
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// NOTE: this method should be called from body click/keypress event handlers to increase entropy
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sr.seedTime = function () {
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sr.seedInt(new Date().getTime());
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}
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sr.getByte = function () {
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if (sr.state == null) {
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sr.seedTime();
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sr.state = sr.ArcFour(); // Plug in your RNG constructor here
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sr.state.init(sr.pool);
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sr.poolCopyOnInit = [];
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for (sr.pptr = 0; sr.pptr < sr.pool.length; ++sr.pptr)
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sr.poolCopyOnInit[sr.pptr] = sr.pool[sr.pptr];
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sr.pptr = 0;
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}
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// TODO: allow reseeding after first request
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return sr.state.next();
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}
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// Mix in a 32-bit integer into the pool
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sr.seedInt = function (x) {
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sr.seedInt8(x);
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sr.seedInt8((x >> 8));
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sr.seedInt8((x >> 16));
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sr.seedInt8((x >> 24));
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}
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// Mix in a 16-bit integer into the pool
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sr.seedInt16 = function (x) {
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sr.seedInt8(x);
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sr.seedInt8((x >> 8));
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}
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// Mix in a 8-bit integer into the pool
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sr.seedInt8 = function (x) {
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sr.pool[sr.pptr++] ^= x & 255;
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if (sr.pptr >= sr.poolSize) sr.pptr -= sr.poolSize;
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}
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// Arcfour is a PRNG
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sr.ArcFour = function () {
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function Arcfour() {
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this.i = 0;
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this.j = 0;
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this.S = new Array();
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}
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// Initialize arcfour context from key, an array of ints, each from [0..255]
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function ARC4init(key) {
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var i, j, t;
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for (i = 0; i < 256; ++i)
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this.S[i] = i;
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j = 0;
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for (i = 0; i < 256; ++i) {
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j = (j + this.S[i] + key[i % key.length]) & 255;
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t = this.S[i];
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this.S[i] = this.S[j];
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this.S[j] = t;
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}
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this.i = 0;
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this.j = 0;
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}
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function ARC4next() {
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var t;
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this.i = (this.i + 1) & 255;
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this.j = (this.j + this.S[this.i]) & 255;
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t = this.S[this.i];
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this.S[this.i] = this.S[this.j];
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this.S[this.j] = t;
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return this.S[(t + this.S[this.i]) & 255];
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}
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Arcfour.prototype.init = ARC4init;
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Arcfour.prototype.next = ARC4next;
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return new Arcfour();
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};
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// Initialize the pool with junk if needed.
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if (sr.pool == null) {
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sr.pool = new Array();
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sr.pptr = 0;
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var t;
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if (window.crypto && window.crypto.getRandomValues && window.Uint8Array) {
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try {
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// Use webcrypto if available
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var ua = new Uint8Array(sr.poolSize);
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window.crypto.getRandomValues(ua);
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for (t = 0; t < sr.poolSize; ++t)
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sr.pool[sr.pptr++] = ua[t];
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} catch (e) { alert(e); }
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}
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while (sr.pptr < sr.poolSize) { // extract some randomness from Math.random()
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t = Math.floor(65536 * Math.random());
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sr.pool[sr.pptr++] = t >>> 8;
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sr.pool[sr.pptr++] = t & 255;
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}
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sr.pptr = Math.floor(sr.poolSize * Math.random());
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sr.seedTime();
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// entropy
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var entropyStr = "";
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// screen size and color depth: ~4.8 to ~5.4 bits
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entropyStr += (window.screen.height * window.screen.width * window.screen.colorDepth);
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entropyStr += (window.screen.availHeight * window.screen.availWidth * window.screen.pixelDepth);
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// time zone offset: ~4 bits
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var dateObj = new Date();
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var timeZoneOffset = dateObj.getTimezoneOffset();
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entropyStr += timeZoneOffset;
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// user agent: ~8.3 to ~11.6 bits
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entropyStr += navigator.userAgent;
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// browser plugin details: ~16.2 to ~21.8 bits
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var pluginsStr = "";
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for (var i = 0; i < navigator.plugins.length; i++) {
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pluginsStr += navigator.plugins[i].name + " " + navigator.plugins[i].filename + " " + navigator.plugins[i].description + " " + navigator.plugins[i].version + ", ";
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}
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var mimeTypesStr = "";
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for (var i = 0; i < navigator.mimeTypes.length; i++) {
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mimeTypesStr += navigator.mimeTypes[i].description + " " + navigator.mimeTypes[i].type + " " + navigator.mimeTypes[i].suffixes + ", ";
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}
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entropyStr += pluginsStr + mimeTypesStr;
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// cookies and storage: 1 bit
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entropyStr += navigator.cookieEnabled + typeof (sessionStorage) + typeof (localStorage);
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// language: ~7 bit
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entropyStr += navigator.language;
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// history: ~2 bit
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entropyStr += window.history.length;
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// location
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entropyStr += window.location;
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var entropyBytes = Crypto.SHA256(entropyStr, { asBytes: true });
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for (var i = 0 ; i < entropyBytes.length ; i++) {
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sr.seedInt8(entropyBytes[i]);
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}
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}
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})(); |