/**
*
*  Secure Hash Algorithm (SHA256)
*  http://www.cuaimacrypt.com/
*
*  Programado por Julian Bolivar
*
**/

function sha256(sa, sb){

	var chrsz   = 8;
	var hexcase = 0;
	var b64pad  = "";
  var strt    = "";
  var lsa     = sa.length;
  var lsb     = sb.length;
  var vsa     = "";
  var vsb     = "";

	function safe_add (x, y) {
		var lsw = (x & 0xFFFF) + (y & 0xFFFF);
		var msw = (x >> 16) + (y >> 16) + (lsw >> 16);
		return (msw << 16) | (lsw & 0xFFFF);
	}

	function S (X, n) { return ( X >>> n ) | (X << (32 - n)); }
	function R (X, n) { return ( X >>> n ); }
	function Ch(x, y, z) { return ((x & y) ^ ((~x) & z)); }
	function Maj(x, y, z) { return ((x & y) ^ (x & z) ^ (y & z)); }
	function Sigma0256(x) { return (S(x, 2) ^ S(x, 13) ^ S(x, 22)); }
	function Sigma1256(x) { return (S(x, 6) ^ S(x, 11) ^ S(x, 25)); }
	function Gamma0256(x) { return (S(x, 7) ^ S(x, 18) ^ R(x, 3)); }
	function Gamma1256(x) { return (S(x, 17) ^ S(x, 19) ^ R(x, 10)); }

	function core_sha256 (m, l) {
		var K = new Array(0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5, 0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5, 0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3, 0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174, 0xE49B69C1, 0xEFBE4786, 0xFC19DC6, 0x240CA1CC, 0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA, 0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7, 0xC6E00BF3, 0xD5A79147, 0x6CA6351, 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 HASH = new Array(0x6A09E667, 0xBB67AE85, 0x3C6EF372, 0xA54FF53A, 0x510E527F, 0x9B05688C, 0x1F83D9AB, 0x5BE0CD19);
		var W = new Array(64);
		var a, b, c, d, e, f, g, h, i, j;
		var T1, T2;

		m[l >> 5] |= 0x80 << (24 - l % 32);
		m[((l + 64 >> 9) << 4) + 15] = l;

		for ( var i = 0; i<m.length; i+=16 ) {
			a = HASH[0];
			b = HASH[1];
			c = HASH[2];
			d = HASH[3];
			e = HASH[4];
			f = HASH[5];
			g = HASH[6];
			h = HASH[7];

			for ( var j = 0; j<64; j++) {
				if (j < 16) W[j] = m[j + i];
				else W[j] = safe_add(safe_add(safe_add(Gamma1256(W[j - 2]), W[j - 7]), Gamma0256(W[j - 15])), W[j - 16]);

				T1 = safe_add(safe_add(safe_add(safe_add(h, Sigma1256(e)), Ch(e, f, g)), K[j]), W[j]);
				T2 = safe_add(Sigma0256(a), Maj(a, b, c));

				h = g;
				g = f;
				f = e;
				e = safe_add(d, T1);
				d = c;
				c = b;
				b = a;
				a = safe_add(T1, T2);
			}

			HASH[0] = safe_add(a, HASH[0]);
			HASH[1] = safe_add(b, HASH[1]);
			HASH[2] = safe_add(c, HASH[2]);
			HASH[3] = safe_add(d, HASH[3]);
			HASH[4] = safe_add(e, HASH[4]);
			HASH[5] = safe_add(f, HASH[5]);
			HASH[6] = safe_add(g, HASH[6]);
			HASH[7] = safe_add(h, HASH[7]);
		}
		return HASH;
	}

	function str2binb (str) {
		var bin = Array();
		var mask = (1 << chrsz) - 1;
		for(var i = 0; i < str.length * chrsz; i += chrsz) {
			bin[i>>5] |= (str.charCodeAt(i / chrsz) & mask) << (24 - i%32);
		}
		return bin;
	}

	function Utf8Encode(string) {
		string = string.replace(/\r\n/g,"\n");
		var utftext = "";

		for (var n = 0; n < string.length; n++) {

			var c = string.charCodeAt(n);

			if (c < 128) {
				utftext += String.fromCharCode(c);
			}
			else if((c > 127) && (c < 2048)) {
				utftext += String.fromCharCode((c >> 6) | 192);
				utftext += String.fromCharCode((c & 63) | 128);
			}
			else {
				utftext += String.fromCharCode((c >> 12) | 224);
				utftext += String.fromCharCode(((c >> 6) & 63) | 128);
				utftext += String.fromCharCode((c & 63) | 128);
			}

		}

		return utftext;
	}

	function binb2hex (binarray) {
		var hex_tab = hexcase ? "0123456789ABCDEF" : "0123456789abcdef";
		var str = "";
		for(var i = 0; i < binarray.length * 4; i++) {
			str += hex_tab.charAt((binarray[i>>2] >> ((3 - i%4)*8+4)) & 0xF) +
			hex_tab.charAt((binarray[i>>2] >> ((3 - i%4)*8  )) & 0xF);
		}
		return str;
	}

  function binb2b64(binarray)
  {
    var tab = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    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 += tab.charAt((triplet >> 6*(3-j)) & 0x3F);
      }
    }
    return str;
  }
 
  function binb2str(bin)
  {
    var str = "";
    var mask = (1 << chrsz) - 1;
    for(var i = 0; i < bin.length * 32; i += chrsz)
      str += String.fromCharCode((bin[i>>5] >>> (24 - i%32)) & mask);
    return str;
  }


  if(lsa > lsb) {
  	for(var i = 0; i < lsb ; i++) {
  		vsa = sa.charAt(i);
  		vsb = sb.charAt(i);
  		strt = strt.concat(vsa,vsb);
  	}
  	vsa = sa.substr(i);
  	strt = strt.concat(vsa);
  }
  else {
  	for(var i = 0; i < lsa ; i++) {
  		vsa = sa.charAt(i);
  		vsb = sb.charAt(i);
  		strt = strt.concat(vsb,vsa);
  	}
  	vsb = sb.substr(i);
  	strt = strt.concat(vsb);
  }
	var s = Utf8Encode(strt);
	return binb2b64(core_sha256(str2binb(s), s.length * chrsz));
  
}