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static/plugins/spice-html5/rng.js 3.29 KB
831eac332   zhuzhenchao   add file
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  // Downloaded from http://www-cs-students.stanford.edu/~tjw/jsbn/ by Jeremy White on 6/1/2012
  
  /*
   * Copyright (c) 2003-2005  Tom Wu
   * All Rights Reserved.
   *
   * Permission is hereby granted, free of charge, to any person obtaining
   * a copy of this software and associated documentation files (the
   * "Software"), to deal in the Software without restriction, including
   * without limitation the rights to use, copy, modify, merge, publish,
   * distribute, sublicense, and/or sell copies of the Software, and to
   * permit persons to whom the Software is furnished to do so, subject to
   * the following conditions:
   *
   * The above copyright notice and this permission notice shall be
   * included in all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND, 
   * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY 
   * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.  
   *
   * IN NO EVENT SHALL TOM WU BE LIABLE FOR ANY SPECIAL, INCIDENTAL,
   * INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR ANY DAMAGES WHATSOEVER
   * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER OR NOT ADVISED OF
   * THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF LIABILITY, ARISING OUT
   * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   *
   * In addition, the following condition applies:
   *
   * All redistributions must retain an intact copy of this copyright notice
   * and disclaimer.
   */
  
  
  // 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;