/*! * Random number generator with ArcFour PRNG * * NOTE: For best results, put code like * * in your main HTML document. * * Copyright Tom Wu, bitaddress.org BSD License. * http://www-cs-students.stanford.edu/~tjw/jsbn/LICENSE */ (function () { // Constructor function of Global SecureRandom object var sr = window.SecureRandom = function () { }; // Properties sr.state; sr.pool; sr.pptr; sr.poolCopyOnInit; // Pool size must be a multiple of 4 and greater than 32. // An array of bytes the size of the pool will be passed to init() sr.poolSize = 256; // --- object methods --- // public method // ba: byte array sr.prototype.nextBytes = function (ba) { var i; if (window.crypto && window.crypto.getRandomValues && window.Uint8Array) { try { var rvBytes = new Uint8Array(ba.length); window.crypto.getRandomValues(rvBytes); for (i = 0; i < ba.length; ++i) ba[i] = sr.getByte() ^ rvBytes[i]; return; } catch (e) { alert(e); } } for (i = 0; i < ba.length; ++i) ba[i] = sr.getByte(); }; // --- static methods --- // Mix in the current time (w/milliseconds) into the pool // NOTE: this method should be called from body click/keypress event handlers to increase entropy sr.seedTime = function () { sr.seedInt(new Date().getTime()); } sr.getByte = function () { if (sr.state == null) { sr.seedTime(); sr.state = sr.ArcFour(); // Plug in your RNG constructor here sr.state.init(sr.pool); sr.poolCopyOnInit = []; for (sr.pptr = 0; sr.pptr < sr.pool.length; ++sr.pptr) sr.poolCopyOnInit[sr.pptr] = sr.pool[sr.pptr]; sr.pptr = 0; } // TODO: allow reseeding after first request return sr.state.next(); } // Mix in a 32-bit integer into the pool sr.seedInt = function (x) { sr.seedInt8(x); sr.seedInt8((x >> 8)); sr.seedInt8((x >> 16)); sr.seedInt8((x >> 24)); } // Mix in a 16-bit integer into the pool sr.seedInt16 = function (x) { sr.seedInt8(x); sr.seedInt8((x >> 8)); } // Mix in a 8-bit integer into the pool sr.seedInt8 = function (x) { sr.pool[sr.pptr++] ^= x & 255; if (sr.pptr >= sr.poolSize) sr.pptr -= sr.poolSize; } // Arcfour is a PRNG sr.ArcFour = function () { function Arcfour() { this.i = 0; this.j = 0; this.S = new Array(); } // Initialize arcfour context from key, an array of ints, each from [0..255] function ARC4init(key) { var i, j, t; for (i = 0; i < 256; ++i) this.S[i] = i; j = 0; for (i = 0; i < 256; ++i) { j = (j + this.S[i] + key[i % key.length]) & 255; t = this.S[i]; this.S[i] = this.S[j]; this.S[j] = t; } this.i = 0; this.j = 0; } function ARC4next() { var t; this.i = (this.i + 1) & 255; this.j = (this.j + this.S[this.i]) & 255; t = this.S[this.i]; this.S[this.i] = this.S[this.j]; this.S[this.j] = t; return this.S[(t + this.S[this.i]) & 255]; } Arcfour.prototype.init = ARC4init; Arcfour.prototype.next = ARC4next; return new Arcfour(); }; // Initialize the pool with junk if needed. if (sr.pool == null) { sr.pool = new Array(); sr.pptr = 0; var t; if (window.crypto && window.crypto.getRandomValues && window.Uint8Array) { try { // Use webcrypto if available var ua = new Uint8Array(sr.poolSize); window.crypto.getRandomValues(ua); for (t = 0; t < sr.poolSize; ++t) sr.pool[sr.pptr++] = ua[t]; } catch (e) { alert(e); } } while (sr.pptr < sr.poolSize) { // extract some randomness from Math.random() t = Math.floor(65536 * Math.random()); sr.pool[sr.pptr++] = t >>> 8; sr.pool[sr.pptr++] = t & 255; } sr.pptr = Math.floor(sr.poolSize * Math.random()); sr.seedTime(); // entropy var entropyStr = ""; // screen size and color depth: ~4.8 to ~5.4 bits entropyStr += (window.screen.height * window.screen.width * window.screen.colorDepth); entropyStr += (window.screen.availHeight * window.screen.availWidth * window.screen.pixelDepth); // time zone offset: ~4 bits var dateObj = new Date(); var timeZoneOffset = dateObj.getTimezoneOffset(); entropyStr += timeZoneOffset; // user agent: ~8.3 to ~11.6 bits entropyStr += navigator.userAgent; // browser plugin details: ~16.2 to ~21.8 bits var pluginsStr = ""; for (var i = 0; i < navigator.plugins.length; i++) { pluginsStr += navigator.plugins[i].name + " " + navigator.plugins[i].filename + " " + navigator.plugins[i].description + " " + navigator.plugins[i].version + ", "; } var mimeTypesStr = ""; for (var i = 0; i < navigator.mimeTypes.length; i++) { mimeTypesStr += navigator.mimeTypes[i].description + " " + navigator.mimeTypes[i].type + " " + navigator.mimeTypes[i].suffixes + ", "; } entropyStr += pluginsStr + mimeTypesStr; // cookies and storage: 1 bit entropyStr += navigator.cookieEnabled + typeof (sessionStorage) + typeof (localStorage); // language: ~7 bit entropyStr += navigator.language; // history: ~2 bit entropyStr += window.history.length; // location entropyStr += window.location; var entropyBytes = Crypto.SHA256(entropyStr, { asBytes: true }); for (var i = 0 ; i < entropyBytes.length ; i++) { sr.seedInt8(entropyBytes[i]); } } })();