var seed1 = "DDIjPzQfeCMeYTQQHxoeDwQBPAIQFA";
var b64pad  = "="; /* base-64 pad character. "=" for strict RFC compliance   */
var table64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
var seed2 = decode(seed1);

/*
 * Calculate the SHA-1 of an array of big-endian words, and a bit length
 */
function core_sha1(x, len)
{
  /* append padding */
  x[len >> 5] |= 0x80 << (24 - len % 32);
  x[((len + 64 >> 9) << 4) + 15] = len;

  var w = Array(80);
  var a =  1732584193;
  var b = -271733879;
  var c = -1732584194;
  var d =  271733878;
  var e = -1009589776;

  for (var i = 0; i < x.length; i += 16)
  {
    var olda = a;
    var oldb = b;
    var oldc = c;
    var oldd = d;
    var olde = e;

    for (var j = 0; j < 80; j++)
    {
      if (j < 16) w[j] = x[i + j];
      else w[j] = rol(w[j-3] ^ w[j-8] ^ w[j-14] ^ w[j-16], 1);
      var t = safe_add(safe_add(rol(a, 5), sha1_ft(j, b, c, d)),
                       safe_add(safe_add(e, w[j]), sha1_kt(j)));
      e = d;
      d = c;
      c = rol(b, 30);
      b = a;
      a = t;
    }

    a = safe_add(a, olda);
    b = safe_add(b, oldb);
    c = safe_add(c, oldc);
    d = safe_add(d, oldd);
    e = safe_add(e, olde);
  }
  return Array(a, b, c, d, e);

}

/*
 * Perform the appropriate triplet combination function for the current
 * iteration
 */
function sha1_ft(t, b, c, d)
{
  if (t < 20) return (b & c) | ((~b) & d);
  if (t < 40) return b ^ c ^ d;
  if (t < 60) return (b & c) | (b & d) | (c & d);
  return b ^ c ^ d;
}

/*
 * Determine the appropriate additive constant for the current iteration
 */
function sha1_kt(t)
{
  return (t < 20) ?  1518500249 : (t < 40) ?  1859775393 :
         (t < 60) ? -1894007588 : -899497514;
}

/*
 * Calculate the HMAC-SHA1 of a key and some data
 */
function core_hmac_sha1(key, data)
{
  var bkey = str2binb(key);
  if (bkey.length > 16) bkey = core_sha1(bkey, key.length*8);

  var ipad = Array(16), opad = Array(16);
  for (var i = 0; i < 16; i++)
  {
    ipad[i] = bkey[i] ^ 0x36363636;
    opad[i] = bkey[i] ^ 0x5C5C5C5C;
  }

  var hash = core_sha1(ipad.concat(str2binb(data)), 512 + data.length*8);
  return core_sha1(opad.concat(hash), 512 + 160);
}

/*
 * Add integers, wrapping at 2^32. This uses 16-bit operations internally
 * to work around bugs in some JS interpreters.
 */
function safe_add(x, y)
{
  var lsw = (x & 0xFFFF) + (y & 0xFFFF);
  var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
  return (msw << 16) | (lsw & 0xFFFF);
}

/*
 * Bitwise rotate a 32-bit number to the left.
 */
function rol(num, cnt)
{
  return (num << cnt) | (num >>> (32 - cnt));
}

/*
 * Convert an 8-bit or 16-bit string to an array of big-endian words
 * In 8-bit function, characters >255 have their hi-byte silently ignored.
 */
function str2binb(str)
{
  var bin = Array();
  for (var i = 0; i < str.length*8; i += 8)
    bin[i>>5] |= (str.charCodeAt(i/8) & 0xFF) << (24 - i%32);
  return bin;
}

/*
 * Convert an array of big-endian words to a base-64 string
 */
function binb2b64(binarray)
{
  var str = "";
  for (var i = 0; i < binarray.length*4; i += 3)
  {
    var triplet = (((binarray[i   >> 2] >> 8 * (3 -  i   %4)) & 0xFF) << 16)
                | (((binarray[i+1 >> 2] >> 8 * (3 - (i+1)%4)) & 0xFF) << 8 )
                |  ((binarray[i+2 >> 2] >> 8 * (3 - (i+2)%4)) & 0xFF);
    for (var j = 0; j < 4; j++)
    {
      if (i*8 + j*6 > binarray.length*32) str += b64pad;
      else str += table64.charAt((triplet >> 6*(3-j)) & 0x3F);
    }
  }
  return str;
}

function b64_hmac_sha1(data)
  {
  return binb2b64(core_hmac_sha1(seed2, data));
  }

/*
 * Convert a character string to a base-64 string
 */
function str2b64(charstring)
  {
  var str = "";
  for (var i = 0; i < charstring.length; i += 3)
    {
    var triplet = ((charstring.charCodeAt(i    ) & 0xFF) << 16)
                | ((charstring.charCodeAt(i + 1) & 0xFF) << 8 )
                |  (charstring.charCodeAt(i + 2) & 0xFF);
    for (var j = 0; j < 4; j++)
      {
      if (i*8 + j*6 > charstring.length*8)
        str += b64pad;
      else
        str += table64.charAt((triplet >> 6*(3 - j)) & 0x3F);
      }
    }
  return str;
  }

function decode(codestr)
  {
  var str = "";
  var len = codestr.indexOf(b64pad);
  if (len < 0)
    len = codestr.length;
  len = Math.floor((len*3)/4 + 0.01);
  for (var i = 0; i < codestr.length; i += 4)
    {
    var triplet = ((table64.indexOf(codestr.charAt(i    )) & 0x3F) << 18)
                | ((table64.indexOf(codestr.charAt(i + 1)) & 0x3F) << 12)
                | ((table64.indexOf(codestr.charAt(i + 2)) & 0x3F) << 6)
                |  (table64.indexOf(codestr.charAt(i + 3)) & 0x3F);
    for (var j = 0; j < 3; j++)
      {
      if (str.length < len)
        str += String.fromCharCode(0x55^((triplet >> 8*(2 - j)) & 0xFF));
      }
    }
  return str;
  }