/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  SHA-1 implementation in JavaScript | (c) Chris Veness 2002-2010 | www.movable-type.co.uk      */
/*   - see http://csrc.nist.gov/groups/ST/toolkit/secure_hashing.html                             */
/*         http://csrc.nist.gov/groups/ST/toolkit/examples.html                                   */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

var Sha1 = {};  // Sha1 namespace

/**
 * Generates SHA-1 hash of string
 *
 * @param {String} msg                String to be hashed
 * @param {Boolean} [utf8encode=true] Encode msg as UTF-8 before generating hash
 * @returns {String}                  Hash of msg as hex character string
 */
Sha1.hash = function(msg, utf8encode) {
  utf8encode =  (typeof utf8encode == 'undefined') ? true : utf8encode;

  // convert string to UTF-8, as SHA only deals with byte-streams
  if (utf8encode) msg = Utf8.encode(msg);

  // constants [§4.2.1]
  var K = [0x5a827999, 0x6ed9eba1, 0x8f1bbcdc, 0xca62c1d6];

  // PREPROCESSING 

  msg += String.fromCharCode(0x80);  // add trailing '1' bit (+ 0's padding) to string [§5.1.1]

  // convert string msg into 512-bit/16-integer blocks arrays of ints [§5.2.1]
  var l = msg.length/4 + 2;  // length (in 32-bit integers) of msg + ‘1’ + appended length
  var N = Math.ceil(l/16);   // number of 16-integer-blocks required to hold 'l' ints
  var M = new Array(N);

  for (var i=0; i>> 32, but since JS converts
  // bitwise-op args to 32 bits, we need to simulate this by arithmetic operators
  M[N-1][14] = ((msg.length-1)*8) / Math.pow(2, 32); M[N-1][14] = Math.floor(M[N-1][14])
  M[N-1][15] = ((msg.length-1)*8) & 0xffffffff;

  // set initial hash value [§5.3.1]
  var H0 = 0x67452301;
  var H1 = 0xefcdab89;
  var H2 = 0x98badcfe;
  var H3 = 0x10325476;
  var H4 = 0xc3d2e1f0;

  // HASH COMPUTATION [§6.1.2]

  var W = new Array(80); var a, b, c, d, e;
  for (var i=0; i>>(32-n));
}

//
// hexadecimal representation of a number 
//   (note toString(16) is implementation-dependant, and  
//   in IE returns signed numbers when used on full words)
//
Sha1.toHexStr = function(n) {
  var s="", v;
  for (var i=7; i>=0; i--) { v = (n>>>(i*4)) & 0xf; s += v.toString(16); }
  return s;
}

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  Utf8 class: encode / decode between multi-byte Unicode characters and UTF-8 multiple          */
/*              single-byte character encoding (c) Chris Veness 2002-2010                         */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

var Utf8 = {};  // Utf8 namespace

/**
 * Encode multi-byte Unicode string into utf-8 multiple single-byte characters 
 * (BMP / basic multilingual plane only)
 *
 * Chars in range U+0080 - U+07FF are encoded in 2 chars, U+0800 - U+FFFF in 3 chars
 *
 * @param {String} strUni Unicode string to be encoded as UTF-8
 * @returns {String} encoded string
 */
Utf8.encode = function(strUni) {
  // use regular expressions & String.replace callback function for better efficiency 
  // than procedural approaches
  var strUtf = strUni.replace(
      /[\u0080-\u07ff]/g,  // U+0080 - U+07FF => 2 bytes 110yyyyy, 10zzzzzz
      function(c) { 
        var cc = c.charCodeAt(0);
        return String.fromCharCode(0xc0 | cc>>6, 0x80 | cc&0x3f); }
    );
  strUtf = strUtf.replace(
      /[\u0800-\uffff]/g,  // U+0800 - U+FFFF => 3 bytes 1110xxxx, 10yyyyyy, 10zzzzzz
      function(c) { 
        var cc = c.charCodeAt(0); 
        return String.fromCharCode(0xe0 | cc>>12, 0x80 | cc>>6&0x3F, 0x80 | cc&0x3f); }
    );
  return strUtf;
}

/**
 * Decode utf-8 encoded string back into multi-byte Unicode characters
 *
 * @param {String} strUtf UTF-8 string to be decoded back to Unicode
 * @returns {String} decoded string
 */
Utf8.decode = function(strUtf) {
  // note: decode 3-byte chars first as decoded 2-byte strings could appear to be 3-byte char!
  var strUni = strUtf.replace(
      /[\u00e0-\u00ef][\u0080-\u00bf][\u0080-\u00bf]/g,  // 3-byte chars
      function(c) {  // (note parentheses for precence)
        var cc = ((c.charCodeAt(0)&0x0f)<<12) | ((c.charCodeAt(1)&0x3f)<<6) | ( c.charCodeAt(2)&0x3f); 
        return String.fromCharCode(cc); }
    );
  strUni = strUni.replace(
      /[\u00c0-\u00df][\u0080-\u00bf]/g,                 // 2-byte chars
      function(c) {  // (note parentheses for precence)
        var cc = (c.charCodeAt(0)&0x1f)<<6 | c.charCodeAt(1)&0x3f;
        return String.fromCharCode(cc); }
    );
  return strUni;
}

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
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