(function(root, undefined){
  'use strict';

  var HEX_CHARS = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'];
  var HEX_TABLE = {
    '0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5, '6': 6, '7': 7, '8': 8, '9': 9,
    'a': 10, 'b': 11, 'c': 12, 'd': 13, 'e': 14, 'f': 15,
    'A': 10, 'B': 11, 'C': 12, 'D': 13, 'E': 14, 'F': 15
  };

  var K =[0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
          0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
          0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
          0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
          0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
          0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
          0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
          0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2];

  var sha256 = function(message) {
    return sha2(message, true);
  };

  var sha224 = function(message) {
    return sha2(message, false);
  };

  var sha2 = function(message, is256) {
    if(is256 === undefined)
      is256 = true;

    var blocks = hasUTF8(message) ? UTF8toBlocks(message) : ASCIItoBlocks(message);
    if(is256)
    {
      var h0 = 0x6a09e667;
      var h1 = 0xbb67ae85;
      var h2 = 0x3c6ef372;
      var h3 = 0xa54ff53a;
      var h4 = 0x510e527f;
      var h5 = 0x9b05688c;
      var h6 = 0x1f83d9ab;
      var h7 = 0x5be0cd19;
    }
    else // 224
    {
      var h0 = 0xc1059ed8;
      var h1 = 0x367cd507;
      var h2 = 0x3070dd17;
      var h3 = 0xf70e5939;
      var h4 = 0xffc00b31;
      var h5 = 0x68581511;
      var h6 = 0x64f98fa7;
      var h7 = 0xbefa4fa4;
    }

    for(var i = 0, length = blocks.length;i < length;i += 16)
    {
      var w = [], s0, s1;
      for(var j = 0;j < 16;++j)
        w[j] = blocks[i + j];
      for(var j = 16;j < 64;++j)
      {
        s0 = rightrotate(w[j - 15], 7) ^ rightrotate(w[j - 15], 18) ^ (w[j - 15] >>> 3);
        s1 = rightrotate(w[j - 2], 17) ^ rightrotate(w[j - 2], 19) ^ (w[j - 2] >>> 10);
        w[j] = w[j - 16] + s0 + w[j - 7] + s1;
      }

      var a = h0;
      var b = h1;
      var c = h2;
      var d = h3;
      var e = h4;
      var f = h5;
      var g = h6;
      var h = h7;
      var maj, t1, t2, ch;

      for(var j = 0;j < 64;++j)
      {
        s0 = rightrotate(a, 2) ^ rightrotate(a, 13) ^ rightrotate(a, 22);
        maj = (a & b) ^ (a & c) ^ (b & c);
        t2 = s0 + maj;
        s1 = rightrotate(e, 6) ^ rightrotate(e, 11) ^ rightrotate(e, 25);
        ch = (e & f) ^ ((~ e) & g);
        t1 = (h + s1 + ch + K[j] + w[j]) & 0xffffffff;

        h = g;
        g = f;
        f = e;
        e = d + t1;
        d = c;
        c = b;
        b = a;
        a = t1 + t2;
      }

      h0 += a;
      h1 += b;
      h2 += c;
      h3 += d;
      h4 += e;
      h5 += f;
      h6 += g;
      h7 += h;
    }

    var hex = toHexString(h0) + toHexString(h1)+ toHexString(h2) + toHexString(h3) + toHexString(h4) + toHexString(h5) + toHexString(h6);
    if(is256)
      hex += toHexString(h7);
    return hex;
  };

  var rightrotate = function(x, c) {
    return (x >>> c) | (x << (32 - c));
  };

  var toHexString = function(num) {
    var hex = "";
    for(var i = 0; i < 4; i++)
    {
      var offset = 3 - i << 3;
      hex += HEX_CHARS[(num >> (offset + 4)) & 0x0F] + HEX_CHARS[(num >> offset) & 0x0F];
    }
    return hex;
  };
  
  var hasUTF8 = function(message) {
    var i = message.length;
    while(i--)
      if(message.charCodeAt(i) > 255)
        return true;
    return false;
  };

  var ASCIItoBlocks = function(message) {
    // a block is 32 bits(4 bytes), a chunk is 512 bits(64 bytes)
    var length = message.length;
    var chunkCount = ((length + 8) >> 6) + 1;
    var blockCount = chunkCount << 4; // chunkCount * 16
    var blocks = [];
    var i;
    for(i = 0;i < blockCount;++i)
      blocks[i] = 0;
    for(i = 0;i < length;++i)
      blocks[i >> 2] |= message.charCodeAt(i) << (3 - (i % 4) << 3);
    blocks[i >> 2] |= 0x80 << (3 - (i % 4) << 3);
    blocks[blockCount - 1] = length << 3; // length * 8
    return blocks;
  };
  
  var UTF8toBlocks = function(message) {
    var uri = encodeURIComponent(message);
    var blocks = [];
    for(var i = 0, bytes = 0, length = uri.length;i < length;++i)
    {
      var c = uri.charCodeAt(i);
      if(c == 37) // %
        blocks[bytes >> 2] |= ((HEX_TABLE[uri.charAt(++i)] << 4) | HEX_TABLE[uri.charAt(++i)]) << (3 - (bytes % 4) << 3);
      else
        blocks[bytes >> 2] |= c << (3 - (bytes % 4) << 3);
      ++bytes;
    }
    var chunkCount = ((bytes + 8) >> 6) + 1;
    var blockCount = chunkCount << 4; // chunkCount * 16
    var index = bytes >> 2;
    blocks[index] |= 0x80 << (3 - (bytes % 4) << 3);
    for(var i = index + 1;i < blockCount;++i)
      blocks[i] = 0;
    blocks[blockCount - 1] = bytes << 3; // bytes * 8
    return blocks;
  };

  if(typeof(module) != 'undefined')
  {
    sha256.sha256 = sha256;
    sha256.sha224 = sha224;
    module.exports = sha256;
  }
  else if(root)
  {
    root.sha256 = sha256;
    root.sha224 = sha224;
  }
}(this));