//
// MD4Managed.cs - Message Digest 4 Managed Implementation
//
// Author:
//	Sebastien Pouliot (sebastien@ximian.com)
//
// (C) 2003 Motus Technologies Inc. (http://www.motus.com)
// Copyright (C) 2004-2005,2010 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//

using System;

namespace Mono.Security.Cryptography { 

	// References:
	// a.     RFC1320: The MD4 Message-Digest Algorithm
	//        http://www.ietf.org/rfc/rfc1320.txt

#if !INSIDE_CORLIB
	public
#endif
	class MD4Managed : MD4 {

		private uint[] state;
		private byte[] buffer;
		private uint[] count;
		private uint[] x;

		private const int S11 = 3;
		private const int S12 = 7;
		private const int S13 = 11;
		private const int S14 = 19;
		private const int S21 = 3;
		private const int S22 = 5;
		private const int S23 = 9;
		private const int S24 = 13;
		private const int S31 = 3;
		private const int S32 = 9;
		private const int S33 = 11;
		private const int S34 = 15;

		private byte[] digest;

		//--- constructor -----------------------------------------------------------
                
		public MD4Managed ()
		{
			// we allocate the context memory
			state = new uint [4];
			count = new uint [2];
			buffer = new byte [64];
			digest = new byte [16];
			// temporary buffer in MD4Transform that we don't want to keep allocate on each iteration
			x = new uint [16];
			// the initialize our context
			Initialize ();
		}

		public override void Initialize ()
		{
			count [0] = 0;
			count [1] = 0;
			state [0] = 0x67452301;
			state [1] = 0xefcdab89;
			state [2] = 0x98badcfe;
			state [3] = 0x10325476;
			// Zeroize sensitive information
			Array.Clear (buffer, 0, 64);
			Array.Clear (x, 0, 16);
		}

		protected override void HashCore (byte[] array, int ibStart, int cbSize)
		{
			/* Compute number of bytes mod 64 */
			int index = (int) ((count [0] >> 3) & 0x3F);
			/* Update number of bits */
			count [0] += (uint) (cbSize << 3);
			if (count [0] < (cbSize << 3))
				count [1]++;
			count [1] += (uint) (cbSize >> 29);

			int partLen = 64 - index;
			int i = 0;
			/* Transform as many times as possible. */
			if (cbSize >= partLen) {
				//MD4_memcpy((POINTER)&context->buffer[index], (POINTER)input, partLen);
				Buffer.BlockCopy (array, ibStart, buffer, index, partLen);
				MD4Transform (state, buffer, 0);

				for (i = partLen; i + 63 < cbSize; i += 64) {
					// MD4Transform (context->state, &input[i]);
					MD4Transform (state, array, ibStart + i);
				}

				index = 0;
			}

			/* Buffer remaining input */
			//MD4_memcpy ((POINTER)&context->buffer[index], (POINTER)&input[i], inputLen-i);
			Buffer.BlockCopy (array, ibStart + i, buffer, index, (cbSize-i));
		}

		protected override byte[] HashFinal ()
		{
			/* Save number of bits */
			byte[] bits = new byte [8];
			Encode (bits, count);

			/* Pad out to 56 mod 64. */
			uint index = ((count [0] >> 3) & 0x3f);
			int padLen = (int) ((index < 56) ? (56 - index) : (120 - index));
			HashCore (Padding (padLen), 0, padLen);

			/* Append length (before padding) */
			HashCore (bits, 0, 8);

			/* Store state in digest */
			Encode (digest, state);

			// Zeroize sensitive information.
			Initialize ();

			return digest;
		}

		//--- private methods ---------------------------------------------------

		private byte[] Padding (int nLength) 
		{
			if (nLength > 0) {
				byte[] padding = new byte [nLength];
				padding [0] = 0x80;
				return padding;
			}
			return null;
		}

		/* F, G and H are basic MD4 functions. */
		private uint F (uint x, uint y, uint z) 
		{
			return (uint) (((x) & (y)) | ((~x) & (z)));
		}

		private uint G (uint x, uint y, uint z) 
		{
			return (uint) (((x) & (y)) | ((x) & (z)) | ((y) & (z)));
		}

		private uint H (uint x, uint y, uint z) 
		{
			return (uint) ((x) ^ (y) ^ (z));
		}

		/* ROTATE_LEFT rotates x left n bits. */
		private uint ROL (uint x, byte n) 
		{
			return (uint) (((x) << (n)) | ((x) >> (32-(n))));
		}

		/* FF, GG and HH are transformations for rounds 1, 2 and 3 */
		/* Rotation is separate from addition to prevent recomputation */
		private void FF (ref uint a, uint b, uint c, uint d, uint x, byte s) 
		{
			a += F (b, c, d) + x;
			a = ROL (a, s);
		}

		private void GG (ref uint a, uint b, uint c, uint d, uint x, byte s) 
		{
			a += G (b, c, d) + x + 0x5a827999;
			a = ROL (a, s);
		}

		private void HH (ref uint a, uint b, uint c, uint d, uint x, byte s) 
		{
			a += H (b, c, d) + x + 0x6ed9eba1;
			a = ROL (a, s);
		}

		private void Encode (byte[] output, uint[] input)
		{
			for (int i = 0, j = 0; j < output.Length; i++, j += 4) {
				output [j]   = (byte)(input [i]);
				output [j+1] = (byte)(input [i] >> 8);
				output [j+2] = (byte)(input [i] >> 16);
				output [j+3] = (byte)(input [i] >> 24);
			}
		}

		private void Decode (uint[] output, byte[] input, int index) 
		{
			for (int i = 0, j = index; i < output.Length; i++, j += 4) {
				output [i] = (uint) ((input [j]) | (input [j+1] << 8) | (input [j+2] << 16) | (input [j+3] << 24));
			}
		}

		private void MD4Transform (uint[] state, byte[] block, int index)
		{
			uint a = state [0];
			uint b = state [1];
			uint c = state [2];
			uint d = state [3];

			Decode (x, block, index);

			/* Round 1 */
			FF (ref a, b, c, d, x[ 0], S11); /* 1 */
			FF (ref d, a, b, c, x[ 1], S12); /* 2 */
			FF (ref c, d, a, b, x[ 2], S13); /* 3 */
			FF (ref b, c, d, a, x[ 3], S14); /* 4 */
			FF (ref a, b, c, d, x[ 4], S11); /* 5 */
			FF (ref d, a, b, c, x[ 5], S12); /* 6 */
			FF (ref c, d, a, b, x[ 6], S13); /* 7 */
			FF (ref b, c, d, a, x[ 7], S14); /* 8 */
			FF (ref a, b, c, d, x[ 8], S11); /* 9 */
			FF (ref d, a, b, c, x[ 9], S12); /* 10 */
			FF (ref c, d, a, b, x[10], S13); /* 11 */
			FF (ref b, c, d, a, x[11], S14); /* 12 */
			FF (ref a, b, c, d, x[12], S11); /* 13 */
			FF (ref d, a, b, c, x[13], S12); /* 14 */
			FF (ref c, d, a, b, x[14], S13); /* 15 */
			FF (ref b, c, d, a, x[15], S14); /* 16 */

			/* Round 2 */
			GG (ref a, b, c, d, x[ 0], S21); /* 17 */
			GG (ref d, a, b, c, x[ 4], S22); /* 18 */
			GG (ref c, d, a, b, x[ 8], S23); /* 19 */
			GG (ref b, c, d, a, x[12], S24); /* 20 */
			GG (ref a, b, c, d, x[ 1], S21); /* 21 */
			GG (ref d, a, b, c, x[ 5], S22); /* 22 */
			GG (ref c, d, a, b, x[ 9], S23); /* 23 */
			GG (ref b, c, d, a, x[13], S24); /* 24 */
			GG (ref a, b, c, d, x[ 2], S21); /* 25 */
			GG (ref d, a, b, c, x[ 6], S22); /* 26 */
			GG (ref c, d, a, b, x[10], S23); /* 27 */
			GG (ref b, c, d, a, x[14], S24); /* 28 */
			GG (ref a, b, c, d, x[ 3], S21); /* 29 */
			GG (ref d, a, b, c, x[ 7], S22); /* 30 */
			GG (ref c, d, a, b, x[11], S23); /* 31 */
			GG (ref b, c, d, a, x[15], S24); /* 32 */

			HH (ref a, b, c, d, x[ 0], S31); /* 33 */
			HH (ref d, a, b, c, x[ 8], S32); /* 34 */
			HH (ref c, d, a, b, x[ 4], S33); /* 35 */
			HH (ref b, c, d, a, x[12], S34); /* 36 */
			HH (ref a, b, c, d, x[ 2], S31); /* 37 */
			HH (ref d, a, b, c, x[10], S32); /* 38 */
			HH (ref c, d, a, b, x[ 6], S33); /* 39 */
			HH (ref b, c, d, a, x[14], S34); /* 40 */
			HH (ref a, b, c, d, x[ 1], S31); /* 41 */
			HH (ref d, a, b, c, x[ 9], S32); /* 42 */
			HH (ref c, d, a, b, x[ 5], S33); /* 43 */
			HH (ref b, c, d, a, x[13], S34); /* 44 */
			HH (ref a, b, c, d, x[ 3], S31); /* 45 */
			HH (ref d, a, b, c, x[11], S32); /* 46 */
			HH (ref c, d, a, b, x[ 7], S33); /* 47 */
			HH (ref b, c, d, a, x[15], S34); /* 48 */

			state [0] += a;
			state [1] += b;
			state [2] += c;
			state [3] += d;
		}
	}
}