//
// System.Security.Cryptography MD5CryptoServiceProvider Class implementation
//
// Authors:
//	Matthew S. Ford (Matthew.S.Ford@Rose-Hulman.Edu)
//	Sebastien Pouliot (spouliot@motus.com)
//
// Copyright 2001 by Matthew S. Ford.
//

namespace System.Security.Cryptography {

	/// <summary>
	/// C# implementation of the MD5 cryptographic hash function.
	/// </summary>
#if NET_1_0
	public class MD5CryptoServiceProvider : MD5 {
#else
	public sealed class MD5CryptoServiceProvider : MD5 {
#endif
		private const int BLOCK_SIZE_BYTES =  64;
		private const int HASH_SIZE_BYTES  =  16;
		private const int HASH_SIZE_BITS   = 128;
		[CLSCompliant(false)] private uint[] _H;
		[CLSCompliant(false)] private uint count;
		private byte[] _ProcessingBuffer;   // Used to start data when passed less than a block worth.
		private int _ProcessingBufferCount; // Counts how much data we have stored that still needs processed.
	
		/// <summary>
		/// Creates a new MD5CryptoServiceProvider.
		/// </summary>
		public MD5CryptoServiceProvider () 
		{
			_H = new uint[4];
			HashSizeValue = HASH_SIZE_BITS;
			_ProcessingBuffer = new byte[BLOCK_SIZE_BYTES];

			Initialize();
		}

		~MD5CryptoServiceProvider () 
		{
			Dispose (false);
		}

		protected override void Dispose (bool disposing) 
		{
			// nothing to do (managed implementation)
		}

		/// <summary>
		/// Drives the hashing function.
		/// </summary>
		/// <param name="rgb">Byte array containing the data to hash.</param>
		/// <param name="start">Where in the input buffer to start.</param>
		/// <param name="size">Size in bytes of the data in the buffer to hash.</param>
		protected override void HashCore (byte[] rgb, int start, int size) 
		{
			int i;
			State = 1;

			if (_ProcessingBufferCount != 0) {
				if (size < (BLOCK_SIZE_BYTES - _ProcessingBufferCount)) {
					System.Buffer.BlockCopy (rgb, start, _ProcessingBuffer, _ProcessingBufferCount, size);
					_ProcessingBufferCount += size;
					return;
				}
				else {
					i = (BLOCK_SIZE_BYTES - _ProcessingBufferCount);
					System.Buffer.BlockCopy (rgb, start, _ProcessingBuffer, _ProcessingBufferCount, i);
					ProcessBlock (_ProcessingBuffer, 0);
					_ProcessingBufferCount = 0;
					start += i;
					size -= i;
				}
			}

			for (i=0; i<size-size%BLOCK_SIZE_BYTES; i += BLOCK_SIZE_BYTES) {
				ProcessBlock (rgb, start+i);
			}

			if (size%BLOCK_SIZE_BYTES != 0) {
				System.Buffer.BlockCopy (rgb, size-size%BLOCK_SIZE_BYTES+start, _ProcessingBuffer, 0, size%BLOCK_SIZE_BYTES);
				_ProcessingBufferCount = size%BLOCK_SIZE_BYTES;
			}
		}
	
		/// <summary>
		/// This finalizes the hash.  Takes the data from the chaining variables and returns it.
		/// </summary>
		protected override byte[] HashFinal () 
		{
			byte[] hash = new byte[16];
			int i, j;

			ProcessFinalBlock(_ProcessingBuffer, 0, _ProcessingBufferCount);

			for (i=0; i<4; i++) {
				for (j=0; j<4; j++) {
					hash[i*4+j] = (byte)(_H[i] >> j*8);
				}
			}

			return hash;
		}

		/// <summary>
		/// Resets the class after use.  Called automatically after hashing is done.
		/// </summary>
		public override void Initialize () 
		{
			count = 0;
			_ProcessingBufferCount = 0;

			_H[0] = 0x67452301;
			_H[1] = 0xefcdab89;
			_H[2] = 0x98badcfe;
			_H[3] = 0x10325476;
		}

		/// <summary>
		/// This is the meat of the hash function.  It is what processes each block one at a time.
		/// </summary>
		/// <param name="inputBuffer">Byte array to process data from.</param>
		/// <param name="inputOffset">Where in the byte array to start processing.</param>
		private void ProcessBlock (byte[] inputBuffer, int inputOffset) 
		{
			uint[] buff = new uint[16];
			uint a, b, c, d;
			int i;
		
			count += BLOCK_SIZE_BYTES;
		
			for (i=0; i<16; i++) {
				buff[i] = (uint)(inputBuffer[inputOffset+4*i])
					| (((uint)(inputBuffer[inputOffset+4*i+1])) <<  8)
					| (((uint)(inputBuffer[inputOffset+4*i+2])) << 16)
					| (((uint)(inputBuffer[inputOffset+4*i+3])) << 24);
			}
		
			a = _H[0];
			b = _H[1];
			c = _H[2];
			d = _H[3];
		
			// This function was unrolled because it seems to be doubling our performance with current compiler/VM.
			// Possibly roll up if this changes.


			// ---- Round 1 --------

			a += (((c ^ d) & b) ^ d) + (uint) Constants.C0 + buff [0];
			a = (a << 7) | (a >> 25);
			a += b;

			d += (((b ^ c) & a) ^ c) + (uint) Constants.C1 + buff [1];
			d = (d << 12) | (d >> 20);
			d += a;

			c += (((a ^ b) & d) ^ b) + (uint) Constants.C2 + buff [2];
			c = (c << 17) | (c >> 15);
			c += d;

			b += (((d ^ a) & c) ^ a) + (uint) Constants.C3 + buff [3];
			b = (b << 22) | (b >> 10);
			b += c;

			a += (((c ^ d) & b) ^ d) + (uint) Constants.C4 + buff [4];
			a = (a << 7) | (a >> 25);
			a += b;

			d += (((b ^ c) & a) ^ c) + (uint) Constants.C5 + buff [5];
			d = (d << 12) | (d >> 20);
			d += a;

			c += (((a ^ b) & d) ^ b) + (uint) Constants.C6 + buff [6];
			c = (c << 17) | (c >> 15);
			c += d;

			b += (((d ^ a) & c) ^ a) + (uint) Constants.C7 + buff [7];
			b = (b << 22) | (b >> 10);
			b += c;

			a += (((c ^ d) & b) ^ d) + (uint) Constants.C8 + buff [8];
			a = (a << 7) | (a >> 25);
			a += b;

			d += (((b ^ c) & a) ^ c) + (uint) Constants.C9 + buff [9];
			d = (d << 12) | (d >> 20);
			d += a;

			c += (((a ^ b) & d) ^ b) + (uint) Constants.C10 + buff [10];
			c = (c << 17) | (c >> 15);
			c += d;

			b += (((d ^ a) & c) ^ a) + (uint) Constants.C11 + buff [11];
			b = (b << 22) | (b >> 10);
			b += c;

			a += (((c ^ d) & b) ^ d) + (uint) Constants.C12 + buff [12];
			a = (a << 7) | (a >> 25);
			a += b;

			d += (((b ^ c) & a) ^ c) + (uint) Constants.C13 + buff [13];
			d = (d << 12) | (d >> 20);
			d += a;

			c += (((a ^ b) & d) ^ b) + (uint) Constants.C14 + buff [14];
			c = (c << 17) | (c >> 15);
			c += d;

			b += (((d ^ a) & c) ^ a) + (uint) Constants.C15 + buff [15];
			b = (b << 22) | (b >> 10);
			b += c;


			// ---- Round 2 --------
  
			a += (((b ^ c) & d) ^ c) + (uint) Constants.C16 + buff [1];
			a = (a << 5) | (a >> 27);
			a += b;

			d += (((a ^ b) & c) ^ b) + (uint) Constants.C17 + buff [6];
			d = (d << 9) | (d >> 23);
			d += a;

			c += (((d ^ a) & b) ^ a) + (uint) Constants.C18 + buff [11];
			c = (c << 14) | (c >> 18);
			c += d;

			b += (((c ^ d) & a) ^ d) + (uint) Constants.C19 + buff [0];
			b = (b << 20) | (b >> 12);
			b += c;

			a += (((b ^ c) & d) ^ c) + (uint) Constants.C20 + buff [5];
			a = (a << 5) | (a >> 27);
			a += b;

			d += (((a ^ b) & c) ^ b) + (uint) Constants.C21 + buff [10];
			d = (d << 9) | (d >> 23);
			d += a;

			c += (((d ^ a) & b) ^ a) + (uint) Constants.C22 + buff [15];
			c = (c << 14) | (c >> 18);
			c += d;

			b += (((c ^ d) & a) ^ d) + (uint) Constants.C23 + buff [4];
			b = (b << 20) | (b >> 12);
			b += c;

			a += (((b ^ c) & d) ^ c) + (uint) Constants.C24 + buff [9];
			a = (a << 5) | (a >> 27);
			a += b;

			d += (((a ^ b) & c) ^ b) + (uint) Constants.C25 + buff [14];
			d = (d << 9) | (d >> 23);
			d += a;

			c += (((d ^ a) & b) ^ a) + (uint) Constants.C26 + buff [3];
			c = (c << 14) | (c >> 18);
			c += d;

			b += (((c ^ d) & a) ^ d) + (uint) Constants.C27 + buff [8];
			b = (b << 20) | (b >> 12);
			b += c;

			a += (((b ^ c) & d) ^ c) + (uint) Constants.C28 + buff [13];
			a = (a << 5) | (a >> 27);
			a += b;

			d += (((a ^ b) & c) ^ b) + (uint) Constants.C29 + buff [2];
			d = (d << 9) | (d >> 23);
			d += a;

			c += (((d ^ a) & b) ^ a) + (uint) Constants.C30 + buff [7];
			c = (c << 14) | (c >> 18);
			c += d;

			b += (((c ^ d) & a) ^ d) + (uint) Constants.C31 + buff [12];
			b = (b << 20) | (b >> 12);
			b += c;


			// ---- Round 3 --------
  
			a += (b ^ c ^ d) + (uint) Constants.C32 + buff [5];
			a = (a << 4) | (a >> 28);
			a += b;

			d += (a ^ b ^ c) + (uint) Constants.C33 + buff [8];
			d = (d << 11) | (d >> 21);
			d += a;

			c += (d ^ a ^ b) + (uint) Constants.C34 + buff [11];
			c = (c << 16) | (c >> 16);
			c += d;

			b += (c ^ d ^ a) + (uint) Constants.C35 + buff [14];
			b = (b << 23) | (b >> 9);
			b += c;

			a += (b ^ c ^ d) + (uint) Constants.C36 + buff [1];
			a = (a << 4) | (a >> 28);
			a += b;

			d += (a ^ b ^ c) + (uint) Constants.C37 + buff [4];
			d = (d << 11) | (d >> 21);
			d += a;

			c += (d ^ a ^ b) + (uint) Constants.C38 + buff [7];
			c = (c << 16) | (c >> 16);
			c += d;

			b += (c ^ d ^ a) + (uint) Constants.C39 + buff [10];
			b = (b << 23) | (b >> 9);
			b += c;

			a += (b ^ c ^ d) + (uint) Constants.C40 + buff [13];
			a = (a << 4) | (a >> 28);
			a += b;

			d += (a ^ b ^ c) + (uint) Constants.C41 + buff [0];
			d = (d << 11) | (d >> 21);
			d += a;

			c += (d ^ a ^ b) + (uint) Constants.C42 + buff [3];
			c = (c << 16) | (c >> 16);
			c += d;

			b += (c ^ d ^ a) + (uint) Constants.C43 + buff [6];
			b = (b << 23) | (b >> 9);
			b += c;

			a += (b ^ c ^ d) + (uint) Constants.C44 + buff [9];
			a = (a << 4) | (a >> 28);
			a += b;

			d += (a ^ b ^ c) + (uint) Constants.C45 + buff [12];
			d = (d << 11) | (d >> 21);
			d += a;

			c += (d ^ a ^ b) + (uint) Constants.C46 + buff [15];
			c = (c << 16) | (c >> 16);
			c += d;

			b += (c ^ d ^ a) + (uint) Constants.C47 + buff [2];
			b = (b << 23) | (b >> 9);
			b += c;


			// ---- Round 4 --------
  
			a += (((~d) | b) ^ c) + (uint) Constants.C48 + buff [0];
			a = (a << 6) | (a >> 26);
			a += b;

			d += (((~c) | a) ^ b) + (uint) Constants.C49 + buff [7];
			d = (d << 10) | (d >> 22);
			d += a;

			c += (((~b) | d) ^ a) + (uint) Constants.C50 + buff [14];
			c = (c << 15) | (c >> 17);
			c += d;

			b += (((~a) | c) ^ d) + (uint) Constants.C51 + buff [5];
			b = (b << 21) | (b >> 11);
			b += c;

			a += (((~d) | b) ^ c) + (uint) Constants.C52 + buff [12];
			a = (a << 6) | (a >> 26);
			a += b;

			d += (((~c) | a) ^ b) + (uint) Constants.C53 + buff [3];
			d = (d << 10) | (d >> 22);
			d += a;

			c += (((~b) | d) ^ a) + (uint) Constants.C54 + buff [10];
			c = (c << 15) | (c >> 17);
			c += d;

			b += (((~a) | c) ^ d) + (uint) Constants.C55 + buff [1];
			b = (b << 21) | (b >> 11);
			b += c;

			a += (((~d) | b) ^ c) + (uint) Constants.C56 + buff [8];
			a = (a << 6) | (a >> 26);
			a += b;

			d += (((~c) | a) ^ b) + (uint) Constants.C57 + buff [15];
			d = (d << 10) | (d >> 22);
			d += a;

			c += (((~b) | d) ^ a) + (uint) Constants.C58 + buff [6];
			c = (c << 15) | (c >> 17);
			c += d;

			b += (((~a) | c) ^ d) + (uint) Constants.C59 + buff [13];
			b = (b << 21) | (b >> 11);
			b += c;

			a += (((~d) | b) ^ c) + (uint) Constants.C60 + buff [4];
			a = (a << 6) | (a >> 26);
			a += b;

			d += (((~c) | a) ^ b) + (uint) Constants.C61 + buff [11];
			d = (d << 10) | (d >> 22);
			d += a;

			c += (((~b) | d) ^ a) + (uint) Constants.C62 + buff [2];
			c = (c << 15) | (c >> 17);
			c += d;

			b += (((~a) | c) ^ d) + (uint) Constants.C63 + buff [9];
			b = (b << 21) | (b >> 11);
			b += c;


			_H[0] += a;
			_H[1] += b;
			_H[2] += c;
			_H[3] += d;
		}
		
		/// <summary>
		/// Pads and then processes the final block.
		/// </summary>
		/// <param name="inputBuffer">Buffer to grab data from.</param>
		/// <param name="inputOffset">Position in buffer in bytes to get data from.</param>
		/// <param name="inputCount">How much data in bytes in the buffer to use.</param>
		private void ProcessFinalBlock (byte[] inputBuffer, int inputOffset, int inputCount) 
		{
			byte[] fooBuffer;
			int paddingSize;
			int i;
			uint size;

			paddingSize = (int)(56 - (inputCount + count) % BLOCK_SIZE_BYTES);

			if (paddingSize < 1)
				paddingSize += BLOCK_SIZE_BYTES;


			fooBuffer = new byte[inputCount+paddingSize+8];

			for (i=0; i<inputCount; i++) {
				fooBuffer[i] = inputBuffer[i+inputOffset];
			}

			fooBuffer[inputCount] = 0x80;
			for (i=inputCount+1; i<inputCount+paddingSize; i++) {
				fooBuffer[i] = 0x00;
			}

			size = (uint)(count+inputCount);
			size *= 8;
			fooBuffer[inputCount+paddingSize] = (byte)((size) >>  0);
			fooBuffer[inputCount+paddingSize+1] = (byte)((size) >>  8);
			fooBuffer[inputCount+paddingSize+2] = (byte)((size) >> 16);
			fooBuffer[inputCount+paddingSize+3] = (byte)((size) >> 24);

			fooBuffer[inputCount+paddingSize+4]   = 0x00;
			fooBuffer[inputCount+paddingSize+5] = 0x00;
			fooBuffer[inputCount+paddingSize+6] = 0x00;
			fooBuffer[inputCount+paddingSize+7] = 0x00;

			ProcessBlock(fooBuffer, 0);

			if (inputCount+paddingSize+8 == 128) {
				ProcessBlock(fooBuffer, 64);
			}
		}
		
		private enum Constants : uint {
			 C0 = 0xd76aa478, C1 = 0xe8c7b756, C2 = 0x242070db,
			 C3 = 0xc1bdceee, C4 = 0xf57c0faf, C5 = 0x4787c62a,
			 C6 = 0xa8304613, C7 = 0xfd469501, C8 = 0x698098d8,
			 C9 = 0x8b44f7af,C10 = 0xffff5bb1,C11 = 0x895cd7be,
			C12 = 0x6b901122,C13 = 0xfd987193,C14 = 0xa679438e,
			C15 = 0x49b40821,C16 = 0xf61e2562,C17 = 0xc040b340,
			C18 = 0x265e5a51,C19 = 0xe9b6c7aa,C20 = 0xd62f105d,
			C21 = 0x02441453,C22 = 0xd8a1e681,C23 = 0xe7d3fbc8,
			C24 = 0x21e1cde6,C25 = 0xc33707d6,C26 = 0xf4d50d87,
			C27 = 0x455a14ed,C28 = 0xa9e3e905,C29 = 0xfcefa3f8,
			C30 = 0x676f02d9,C31 = 0x8d2a4c8a,C32 = 0xfffa3942,
			C33 = 0x8771f681,C34 = 0x6d9d6122,C35 = 0xfde5380c,
			C36 = 0xa4beea44,C37 = 0x4bdecfa9,C38 = 0xf6bb4b60,
			C39 = 0xbebfbc70,C40 = 0x289b7ec6,C41 = 0xeaa127fa,
			C42 = 0xd4ef3085,C43 = 0x04881d05,C44 = 0xd9d4d039,
			C45 = 0xe6db99e5,C46 = 0x1fa27cf8,C47 = 0xc4ac5665,
			C48 = 0xf4292244,C49 = 0x432aff97,C50 = 0xab9423a7,
			C51 = 0xfc93a039,C52 = 0x655b59c3,C53 = 0x8f0ccc92,
			C54 = 0xffeff47d,C55 = 0x85845dd1,C56 = 0x6fa87e4f,
			C57 = 0xfe2ce6e0,C58 = 0xa3014314,C59 = 0x4e0811a1,
			C60 = 0xf7537e82,C61 = 0xbd3af235,C62 = 0x2ad7d2bb,
			C63 = 0xeb86d391
		}

	}
}

