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//------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
//------------------------------------------------------------
namespace System.Runtime
{
static class HashHelper
{
// "derived from the RSA Data Security, Inc. MD5 Message-Digest Algorithm"
// DO NOT USE FOR SECURITY PURPOSES.
public static byte[] ComputeHash(byte[] buffer)
{
int[] shifts = new int[] { 7, 12, 17, 22, 5, 9, 14, 20, 4, 11, 16, 23, 6, 10, 15, 21 };
uint[] sines = new uint[] {
0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, 0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be, 0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa, 0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed, 0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c, 0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05, 0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039, 0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1, 0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391 };
int blocks = (buffer.Length + 8) / 64 + 1;
uint aa = 0x67452301;
uint bb = 0xefcdab89;
uint cc = 0x98badcfe;
uint dd = 0x10325476;
for (int i = 0; i < blocks; i++)
{
byte[] block = buffer;
int offset = i * 64;
if (offset + 64 > buffer.Length)
{
block = new byte[64];
for (int j = offset; j < buffer.Length; j++)
{
block[j - offset] = buffer[j];
}
if (offset <= buffer.Length)
{
block[buffer.Length - offset] = 0x80;
}
if (i == blocks - 1)
{
block[56] = (byte)(buffer.Length << 3);
block[57] = (byte)(buffer.Length >> 5);
block[58] = (byte)(buffer.Length >> 13);
block[59] = (byte)(buffer.Length >> 21);
}
offset = 0;
}
uint a = aa;
uint b = bb;
uint c = cc;
uint d = dd;
uint f;
int g;
for (int j = 0; j < 64; j++)
{
if (j < 16)
{
f = b & c | ~b & d;
g = j;
}
else if (j < 32)
{
f = b & d | c & ~d;
g = 5 * j + 1;
}
else if (j < 48)
{
f = b ^ c ^ d;
g = 3 * j + 5;
}
else
{
f = c ^ (b | ~d);
g = 7 * j;
}
g = (g & 0x0f) * 4 + offset;
uint hold = d;
d = c;
c = b;
b = a + f + sines[j] + (uint)(block[g] + (block[g + 1] << 8) + (block[g + 2] << 16) + (block[g + 3] << 24));
b = b << shifts[j & 3 | j >> 2 & ~3] | b >> 32 - shifts[j & 3 | j >> 2 & ~3];
b += c;
a = hold;
}
aa += a;
bb += b;
cc += c;
dd += d;
}
return new byte[] {
(byte)aa, (byte)(aa >> 8), (byte)(aa >> 16), (byte)(aa >> 24),
(byte)bb, (byte)(bb >> 8), (byte)(bb >> 16), (byte)(bb >> 24),
(byte)cc, (byte)(cc >> 8), (byte)(cc >> 16), (byte)(cc >> 24),
(byte)dd, (byte)(dd >> 8), (byte)(dd >> 16), (byte)(dd >> 24) };
}
}
}
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