private void Transform(byte[] block, int offset)
{
uint a = state[0], b = state[1], c = state[2], d = state[3];
uint[] x = new uint[16];
Decode(x, 0, block, offset, 64);
// Round 1
FF(ref a, b, c, d, x[0], S11, 0xd76aa478); /* 1 */
FF(ref d, a, b, c, x[1], S12, 0xe8c7b756); /* 2 */
FF(ref c, d, a, b, x[2], S13, 0x242070db); /* 3 */
FF(ref b, c, d, a, x[3], S14, 0xc1bdceee); /* 4 */
FF(ref a, b, c, d, x[4], S11, 0xf57c0faf); /* 5 */
FF(ref d, a, b, c, x[5], S12, 0x4787c62a); /* 6 */
FF(ref c, d, a, b, x[6], S13, 0xa8304613); /* 7 */
FF(ref b, c, d, a, x[7], S14, 0xfd469501); /* 8 */
FF(ref a, b, c, d, x[8], S11, 0x698098d8); /* 9 */
FF(ref d, a, b, c, x[9], S12, 0x8b44f7af); /* 10 */
FF(ref c, d, a, b, x[10], S13, 0xffff5bb1); /* 11 */
FF(ref b, c, d, a, x[11], S14, 0x895cd7be); /* 12 */
FF(ref a, b, c, d, x[12], S11, 0x6b901122); /* 13 */
FF(ref d, a, b, c, x[13], S12, 0xfd987193); /* 14 */
FF(ref c, d, a, b, x[14], S13, 0xa679438e); /* 15 */
FF(ref b, c, d, a, x[15], S14, 0x49b40821); /* 16 */
// Round 2
GG(ref a, b, c, d, x[1], S21, 0xf61e2562); /* 17 */
GG(ref d, a, b, c, x[6], S22, 0xc040b340); /* 18 */
GG(ref c, d, a, b, x[11], S23, 0x265e5a51); /* 19 */
GG(ref b, c, d, a, x[0], S24, 0xe9b6c7aa); /* 20 */
GG(ref a, b, c, d, x[5], S21, 0xd62f105d); /* 21 */
GG(ref d, a, b, c, x[10], S22, 0x2441453); /* 22 */
GG(ref c, d, a, b, x[15], S23, 0xd8a1e681); /* 23 */
GG(ref b, c, d, a, x[4], S24, 0xe7d3fbc8); /* 24 */
GG(ref a, b, c, d, x[9], S21, 0x21e1cde6); /* 25 */
GG(ref d, a, b, c, x[14], S22, 0xc33707d6); /* 26 */
GG(ref c, d, a, b, x[3], S23, 0xf4d50d87); /* 27 */
GG(ref b, c, d, a, x[8], S24, 0x455a14ed); /* 28 */
GG(ref a, b, c, d, x[13], S21, 0xa9e3e905); /* 29 */
GG(ref d, a, b, c, x[2], S22, 0xfcefa3f8); /* 30 */
GG(ref c, d, a, b, x[7], S23, 0x676f02d9); /* 31 */
GG(ref b, c, d, a, x[12], S24, 0x8d2a4c8a); /* 32 */
// Round 3
HH(ref a, b, c, d, x[5], S31, 0xfffa3942); /* 33 */
HH(ref d, a, b, c, x[8], S32, 0x8771f681); /* 34 */
HH(ref c, d, a, b, x[11], S33, 0x6d9d6122); /* 35 */
HH(ref b, c, d, a, x[14], S34, 0xfde5380c); /* 36 */
HH(ref a, b, c, d, x[1], S31, 0xa4beea44); /* 37 */
HH(ref d, a, b, c, x[4], S32, 0x4bdecfa9); /* 38 */
HH(ref c, d, a, b, x[7], S33, 0xf6bb4b60); /* 39 */
HH(ref b, c, d, a, x[10], S34, 0xbebfbc70); /* 40 */
HH(ref a, b, c, d, x[13], S31, 0x289b7ec6); /* 41 */
HH(ref d, a, b, c, x[0], S32, 0xeaa127fa); /* 42 */
HH(ref c, d, a, b, x[3], S33, 0xd4ef3085); /* 43 */
HH(ref b, c, d, a, x[6], S34, 0x4881d05); /* 44 */
HH(ref a, b, c, d, x[9], S31, 0xd9d4d039); /* 45 */
HH(ref d, a, b, c, x[12], S32, 0xe6db99e5); /* 46 */
HH(ref c, d, a, b, x[15], S33, 0x1fa27cf8); /* 47 */
HH(ref b, c, d, a, x[2], S34, 0xc4ac5665); /* 48 */
// Round 4
II(ref a, b, c, d, x[0], S41, 0xf4292244); /* 49 */
II(ref d, a, b, c, x[7], S42, 0x432aff97); /* 50 */
II(ref c, d, a, b, x[14], S43, 0xab9423a7); /* 51 */
II(ref b, c, d, a, x[5], S44, 0xfc93a039); /* 52 */
II(ref a, b, c, d, x[12], S41, 0x655b59c3); /* 53 */
II(ref d, a, b, c, x[3], S42, 0x8f0ccc92); /* 54 */
II(ref c, d, a, b, x[10], S43, 0xffeff47d); /* 55 */
II(ref b, c, d, a, x[1], S44, 0x85845dd1); /* 56 */
II(ref a, b, c, d, x[8], S41, 0x6fa87e4f); /* 57 */
II(ref d, a, b, c, x[15], S42, 0xfe2ce6e0); /* 58 */
II(ref c, d, a, b, x[6], S43, 0xa3014314); /* 59 */
II(ref b, c, d, a, x[13], S44, 0x4e0811a1); /* 60 */
II(ref a, b, c, d, x[4], S41, 0xf7537e82); /* 61 */
II(ref d, a, b, c, x[11], S42, 0xbd3af235); /* 62 */
II(ref c, d, a, b, x[2], S43, 0x2ad7d2bb); /* 63 */
II(ref b, c, d, a, x[9], S44, 0xeb86d391); /* 64 */
state[0] += a;
state[1] += b;
state[2] += c;
state[3] += d;
// Zeroize sensitive information.
for (int i = 0; i < x.Length; i++)
x[i] = 0;
}