/*
 * A JavaScript implementation of the RSA Data Security, Inc. MD5 Message
 * Digest Algorithm, as defined in RFC 1321.
 * Copyright (C) Paul Johnston 1999 - 2000.
 * See http://pajhome.org.uk/site/legal.html for details.
 */

/*
 * Convert a 32-bit number to a hex string with ls-byte first
 */
var hex_chr = "0123456789ABCDEF";
function rhex(num)
{
  var str = "";
  for(var j = 0; j <= 3; j++)
    str += hex_chr.charAt((num >> (j * 8 + 4)) & 0x0F) +
           hex_chr.charAt((num >> (j * 8)) & 0x0F);
  return str;
}

/*
 * Convert a string to a sequence of 16-word blocks, stored as an array.
 * Append padding bits and the length, as described in the MD5 standard.
 */
function str2blks_MD5(str)
{
  var nblk = ((str.length + 8) >> 6) + 1;
  var blks = new Array(nblk * 16);
  for(var i = 0; i < nblk * 16; i++) blks[i] = 0;
  for(i = 0; i < str.length; i++)
    blks[i >> 2] |= str.charCodeAt(i) << ((i % 4) * 8);
  blks[i >> 2] |= 0x80 << ((i % 4) * 8);
  blks[nblk * 16 - 2] = str.length * 8;
  return blks;
}

/*
 * Add integers, wrapping at 2^32
 */
function add(x, y)
{
  return ((x&0x7FFFFFFF) + (y&0x7FFFFFFF)) ^ (x&0x80000000) ^ (y&0x80000000);
}

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

/*
 * These functions implement the basic operation for each round of the
 * algorithm.
 */
function cmn(q, a, b, x, s, t)
{
  return add(rol(add(add(a, q), add(x, t)), s), b);
}
function ff(a, b, c, d, x, s, t)
{
  return cmn((b & c) | ((~b) & d), a, b, x, s, t);
}
function gg(a, b, c, d, x, s, t)
{
  return cmn((b & d) | (c & (~d)), a, b, x, s, t);
}
function hh(a, b, c, d, x, s, t)
{
  return cmn(b ^ c ^ d, a, b, x, s, t);
}
function ii(a, b, c, d, x, s, t)
{
  return cmn(c ^ (b | (~d)), a, b, x, s, t);
}

/*
 * Take a string and return the hex representation of its MD5.
 */
function calcMD5(str)
{
  var x = str2blks_MD5(str);
  var a = 0x67452301;
  var b = 0xEFCDAB89;
  var c = 0x98BADCFE;
  var d = 0x10325476;

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

    a = ff(a, b, c, d, x[i+ 0], 7 , 0xD76AA478);
    d = ff(d, a, b, c, x[i+ 1], 12, 0xE8C7B756);
    c = ff(c, d, a, b, x[i+ 2], 17, 0x242070DB);
    b = ff(b, c, d, a, x[i+ 3], 22, 0xC1BDCEEE);
    a = ff(a, b, c, d, x[i+ 4], 7 , 0xF57C0FAF);
    d = ff(d, a, b, c, x[i+ 5], 12, 0x4787C62A);
    c = ff(c, d, a, b, x[i+ 6], 17, 0xA8304613);
    b = ff(b, c, d, a, x[i+ 7], 22, 0xFD469501);
    a = ff(a, b, c, d, x[i+ 8], 7 , 0x698098D8);
    d = ff(d, a, b, c, x[i+ 9], 12, 0x8B44F7AF);
    c = ff(c, d, a, b, x[i+10], 17, 0xFFFF5BB1);
    b = ff(b, c, d, a, x[i+11], 22, 0x895CD7BE);
    a = ff(a, b, c, d, x[i+12], 7 , 0x6B901122);
    d = ff(d, a, b, c, x[i+13], 12, 0xFD987193);
    c = ff(c, d, a, b, x[i+14], 17, 0xA679438E);
    b = ff(b, c, d, a, x[i+15], 22, 0x49B40821);

    a = gg(a, b, c, d, x[i+ 1], 5 , 0xF61E2562);
    d = gg(d, a, b, c, x[i+ 6], 9 , 0xC040B340);
    c = gg(c, d, a, b, x[i+11], 14, 0x265E5A51);
    b = gg(b, c, d, a, x[i+ 0], 20, 0xE9B6C7AA);
    a = gg(a, b, c, d, x[i+ 5], 5 , 0xD62F105D);
    d = gg(d, a, b, c, x[i+10], 9 , 0x02441453);
    c = gg(c, d, a, b, x[i+15], 14, 0xD8A1E681);
    b = gg(b, c, d, a, x[i+ 4], 20, 0xE7D3FBC8);
    a = gg(a, b, c, d, x[i+ 9], 5 , 0x21E1CDE6);
    d = gg(d, a, b, c, x[i+14], 9 , 0xC33707D6);
    c = gg(c, d, a, b, x[i+ 3], 14, 0xF4D50D87);
    b = gg(b, c, d, a, x[i+ 8], 20, 0x455A14ED);
    a = gg(a, b, c, d, x[i+13], 5 , 0xA9E3E905);
    d = gg(d, a, b, c, x[i+ 2], 9 , 0xFCEFA3F8);
    c = gg(c, d, a, b, x[i+ 7], 14, 0x676F02D9);
    b = gg(b, c, d, a, x[i+12], 20, 0x8D2A4C8A);

    a = hh(a, b, c, d, x[i+ 5], 4 , 0xFFFA3942);
    d = hh(d, a, b, c, x[i+ 8], 11, 0x8771F681);
    c = hh(c, d, a, b, x[i+11], 16, 0x6D9D6122);
    b = hh(b, c, d, a, x[i+14], 23, 0xFDE5380C);
    a = hh(a, b, c, d, x[i+ 1], 4 , 0xA4BEEA44);
    d = hh(d, a, b, c, x[i+ 4], 11, 0x4BDECFA9);
    c = hh(c, d, a, b, x[i+ 7], 16, 0xF6BB4B60);
    b = hh(b, c, d, a, x[i+10], 23, 0xBEBFBC70);
    a = hh(a, b, c, d, x[i+13], 4 , 0x289B7EC6);
    d = hh(d, a, b, c, x[i+ 0], 11, 0xEAA127FA);
    c = hh(c, d, a, b, x[i+ 3], 16, 0xD4EF3085);
    b = hh(b, c, d, a, x[i+ 6], 23, 0x04881D05);
    a = hh(a, b, c, d, x[i+ 9], 4 , 0xD9D4D039);
    d = hh(d, a, b, c, x[i+12], 11, 0xE6DB99E5);
    c = hh(c, d, a, b, x[i+15], 16, 0x1FA27CF8);
    b = hh(b, c, d, a, x[i+ 2], 23, 0xC4AC5665);

    a = ii(a, b, c, d, x[i+ 0], 6 , 0xF4292244);
    d = ii(d, a, b, c, x[i+ 7], 10, 0x432AFF97);
    c = ii(c, d, a, b, x[i+14], 15, 0xAB9423A7);
    b = ii(b, c, d, a, x[i+ 5], 21, 0xFC93A039);
    a = ii(a, b, c, d, x[i+12], 6 , 0x655B59C3);
    d = ii(d, a, b, c, x[i+ 3], 10, 0x8F0CCC92);
    c = ii(c, d, a, b, x[i+10], 15, 0xFFEFF47D);
    b = ii(b, c, d, a, x[i+ 1], 21, 0x85845DD1);
    a = ii(a, b, c, d, x[i+ 8], 6 , 0x6FA87E4F);
    d = ii(d, a, b, c, x[i+15], 10, 0xFE2CE6E0);
    c = ii(c, d, a, b, x[i+ 6], 15, 0xA3014314);
    b = ii(b, c, d, a, x[i+13], 21, 0x4E0811A1);
    a = ii(a, b, c, d, x[i+ 4], 6 , 0xF7537E82);
    d = ii(d, a, b, c, x[i+11], 10, 0xBD3AF235);
    c = ii(c, d, a, b, x[i+ 2], 15, 0x2AD7D2BB);
    b = ii(b, c, d, a, x[i+ 9], 21, 0xEB86D391);

    a = add(a, olda);
    b = add(b, oldb);
    c = add(c, oldc);
    d = add(d, oldd);
  }
  return rhex(a) + rhex(b) + rhex(c) + rhex(d);
}
