The MD4 Class.(C#)

/*
Copyright 2002 Blood (eaststarbuy@sina.com)

This code is ported from Norbert Hranitzky's
(norbert.hranitzky@mchp.siemens.de)
Java version.
*/

//reference Namespace
using System;
using System.Text;

namespace Blood.COM.Security
{

/// <summary>
/// Implements the MD4 message digest algorithm in C#
/// </summary>
public class MD4
{

// MD4 specific object variables
//-----------------------------------------------------------------------

/// <summary>
/// The size in bytes of the input block to the transformation algorithm
/// </summary>
private const int BLOCK_LENGTH = 64; // = 512 / 8

/// <summary>
/// 4 32-bit words (interim result)
/// </summary>
private uint[] context = new uint[4];

/// <summary>
/// Number of bytes procesed so far mod. 2 power of 64.
/// </summary>
private long count;

/// <summary>
/// 512-bit input buffer = 16 x 32-bit words holds until it reaches 512 bits
/// </summary>
private byte[] buffer = new byte[BLOCK_LENGTH];

/// <summary>
/// 512-bit work buffer = 16 x 32-bit words
/// </summary>
private uint[] X = new uint[16];

// Constructors
//------------------------------------------------------------------------

public MD4()
{
engineReset();
}

/// <summary>
/// This constructor is here to implement the clonability of this class
/// </summary>
/// <param name="md"> </param>
private MD4(MD4 md): this()
{
//this();
context = (uint[])md.context.Clone();
buffer = (byte[])md.buffer.Clone();
count = md.count;
}

// Clonable method implementation
//-------------------------------------------------------------------------
public object Clone()
{
return new MD4(this);
}

// JCE methods
//-------------------------------------------------------------------------

/// <summary>
/// Resets this object disregarding any temporary data present at the
/// time of the invocation of this call.
/// </summary>
private void engineReset()
{
// initial values of MD4 i.e. A, B, C, D
// as per rfc-1320; they are low-order byte first
context[0] = 0x67452301;
context[1] = 0xEFCDAB89;
context[2] = 0x98BADCFE;
context[3] = 0x10325476;
count = 0L;
for(int i = 0; i < BLOCK_LENGTH; i++)
{
buffer[i] = 0;
}
}

/// <summary>
/// Continues an MD4 message digest using the input byte
/// </summary>
/// <param name="b">byte to input</param>
private void engineUpdate(byte b)
{
// compute number of bytes still unhashed; ie. present in buffer
int i = (int)(count % BLOCK_LENGTH);
count++; // update number of bytes
buffer[i] = b;
if(i == BLOCK_LENGTH - 1)
transform(ref buffer, 0);
}

/// <summary>
/// MD4 block update operation
/// </summary>
/// <remarks>
/// Continues an MD4 message digest operation by filling the buffer,
/// transform(ing) data in 512-bit message block(s), updating the variables
/// context and count, and leaving (buffering) the remaining bytes in buffer
/// for the next update or finish.
/// </remarks>
/// <param name="input">input block</param>
/// <param name="offset">start of meaningful bytes in input</param>
/// <param name="len">count of bytes in input blcok to consider</param>
private void engineUpdate(byte[] input, int offset, int len)
{
// make sure we don't exceed input's allocated size/length
if(offset < 0 || len < 0 || (long)offset + len > input.Length)
{
throw new ArgumentOutOfRangeException();
}

// compute number of bytes still unhashed; ie. present in buffer
int bufferNdx = (int)(count % BLOCK_LENGTH);
count += len; // update number of bytes
int partLen = BLOCK_LENGTH - bufferNdx;
int i = 0;
if(len >= partLen)
{
Array.Copy(input, offset + i, buffer, bufferNdx, partLen);

transform(ref buffer, 0);

for(i = partLen; i + BLOCK_LENGTH - 1 < len; i+= BLOCK_LENGTH)
{
transform(ref input, offset + i);
}
bufferNdx = 0;
}
// buffer remaining input
if(i < len)
{
Array.Copy(input, offset + i, buffer, bufferNdx, len - i);
}
}

/// <summary>
/// Completes the hash computation by performing final operations such
/// as padding. At the return of this engineDigest, the MD engine is
/// reset.
/// </summary>
/// <returns>the array of bytes for the resulting hash value.</returns>
private byte[] engineDigest()
{
// pad output to 56 mod 64; as RFC1320 puts it: congruent to 448 mod 512
int bufferNdx = (int)(count % BLOCK_LENGTH);
int padLen = (bufferNdx < 56) ? (56 - bufferNdx) : (120 - bufferNdx);

// padding is always binary 1 followed by binary 0's
byte[] tail = new byte[padLen + 8];
tail[0] = (byte)0x80;

// append length before final transform
// save number of bits, casting the long to an array of 8 bytes
// save low-order byte first.
for(int i = 0; i < 8 ; i++)
{
tail[padLen + i] = (byte)((count * 8) >> (8 * i));
}

engineUpdate(tail, 0, tail.Length);

byte[] result = new byte[16];
// cast this MD4's context (array of 4 uints) into an array of 16 bytes.
for(int i = 0;i < 4; i++)
{
for(int j = 0; j < 4; j++)
{
result[i * 4 + j] = (byte)(context[i] >> (8 * j));
}
}

// reset the engine
engineReset();
return result;
}

/// <summary>
/// Returns a byte hash from a string
/// </summary>
/// <param name="s">string to hash</param>
/// <returns>byte-array that contains the hash</returns>
public byte[] GetByteHashFromString(string s)
{
byte[] b = Encoding.UTF8.GetBytes(s);
MD4 md4 = new MD4();

md4.engineUpdate(b, 0, b.Length);

return md4.engineDigest();
}

/// <summary>
/// Returns a binary hash from an input byte array
/// </summary>
/// <param name="b">byte-array to hash</param>
/// <returns>binary hash of input</returns>
public byte[] GetByteHashFromBytes(byte[] b)
{
MD4 md4 = new MD4();

md4.engineUpdate(b, 0, b.Length);

return md4.engineDigest();
}

/// <summary>
/// Returns a string that contains the hexadecimal hash
/// </summary>
/// <param name="b">byte-array to input</param>
/// <returns>String that contains the hex of the hash</returns>
public string GetHexHashFromBytes(byte[] b)
{
byte[] e = GetByteHashFromBytes(b);
return bytesToHex(e, e.Length);
}

/// <summary>
/// Returns a byte hash from the input byte
/// </summary>
/// <param name="b">byte to hash</param>
/// <returns>binary hash of the input byte</returns>
public byte[] GetByteHashFromByte(byte b)
{
MD4 md4 = new MD4();

md4.engineUpdate(b);

return md4.engineDigest();
}

/// <summary>
/// Returns a string that contains the hexadecimal hash
/// </summary>
/// <param name="b">byte to hash</param>
/// <returns>String that contains the hex of the hash</returns>
public string GetHexHashFromByte(byte b)
{
byte[] e = GetByteHashFromByte(b);
return bytesToHex(e, e.Length);
}

/// <summary>
/// Returns a string that contains the hexadecimal hash
/// </summary>
/// <param name="s">string to hash</param>
/// <returns>String that contains the hex of the hash</returns>
public string GetHexHashFromString(string s)
{
byte[] b = GetByteHashFromString(s);
return bytesToHex(b, b.Length);
}

private static string bytesToHex(byte[] a, int len)
{
string temp = BitConverter.ToString(a);

// We need to remove the dashes that come from the BitConverter
StringBuilder sb = new StringBuilder((len - 2) / 2); // This should be the final size

for(int i = 0; i < temp.Length ; i++)
{
if(temp[i] != '-')
{
sb.Append(temp[i]);
}
}

return sb.ToString();
}

// own methods
//-----------------------------------------------------------------------------------

/// <summary>
/// MD4 basic transformation
/// </summary>
/// <remarks>
/// Transforms context based on 512 bits from input block starting
/// from the offset'th byte.
/// </remarks>
/// <param name="block">input sub-array</param>
/// <param name="offset">starting position of sub-array</param>
private void transform(ref byte[] block, int offset)
{
// decodes 64 bytes from input block into an array of 16 32-bit
// entities. Use A as a temp var.
for (int i = 0; i < 16; i++)
{
X[i] = ((uint)block[offset++] & 0xFF) |
(((uint)block[offset++] & 0xFF) << 8) |
(((uint)block[offset++] & 0xFF) << 16) |
(((uint)block[offset++] & 0xFF) << 24);
}

uint A = context[0];
uint B = context[1];
uint C = context[2];
uint D = context[3];

A = FF(A, B, C, D, X[ 0], 3);
D = FF(D, A, B, C, X[ 1], 7);
C = FF(C, D, A, B, X[ 2], 11);
B = FF(B, C, D, A, X[ 3], 19);
A = FF(A, B, C, D, X[ 4], 3);
D = FF(D, A, B, C, X[ 5], 7);
C = FF(C, D, A, B, X[ 6], 11);
B = FF(B, C, D, A, X[ 7], 19);
A = FF(A, B, C, D, X[ 8], 3);
D = FF(D, A, B, C, X[ 9], 7);
C = FF(C, D, A, B, X[10], 11);
B = FF(B, C, D, A, X[11], 19);
A = FF(A, B, C, D, X[12], 3);
D = FF(D, A, B, C, X[13], 7);
C = FF(C, D, A, B, X[14], 11);
B = FF(B, C, D, A, X[15], 19);

A = GG(A, B, C, D, X[ 0], 3);
D = GG(D, A, B, C, X[ 4], 5);
C = GG(C, D, A, B, X[ 8], 9);
B = GG(B, C, D, A, X[12], 13);
A = GG(A, B, C, D, X[ 1], 3);
D = GG(D, A, B, C, X[ 5], 5);
C = GG(C, D, A, B, X[ 9], 9);
B = GG(B, C, D, A, X[13], 13);
A = GG(A, B, C, D, X[ 2], 3);
D = GG(D, A, B, C, X[ 6], 5);
C = GG(C, D, A, B, X[10], 9);
B = GG(B, C, D, A, X[14], 13);
A = GG(A, B, C, D, X[ 3], 3);
D = GG(D, A, B, C, X[ 7], 5);
C = GG(C, D, A, B, X[11], 9);
B = GG(B, C, D, A, X[15], 13);

A = HH(A, B, C, D, X[ 0], 3);
D = HH(D, A, B, C, X[ 8], 9);
C = HH(C, D, A, B, X[ 4], 11);
B = HH(B, C, D, A, X[12], 15);
A = HH(A, B, C, D, X[ 2], 3);
D = HH(D, A, B, C, X[10], 9);
C = HH(C, D, A, B, X[ 6], 11);
B = HH(B, C, D, A, X[14], 15);
A = HH(A, B, C, D, X[ 1], 3);
D = HH(D, A, B, C, X[ 9], 9);
C = HH(C, D, A, B, X[ 5], 11);
B = HH(B, C, D, A, X[13], 15);
A = HH(A, B, C, D, X[ 3], 3);
D = HH(D, A, B, C, X[11], 9);
C = HH(C, D, A, B, X[ 7], 11);
B = HH(B, C, D, A, X[15], 15);

context[0] += A;
context[1] += B;
context[2] += C;
context[3] += D;
}

// The basic MD4 atomic functions.

private uint FF(uint a, uint b, uint c, uint d, uint x, int s)
{
uint t = a + ((b & c) | (~b & d)) + x;
return t << s | t >> (32 - s);
}
private uint GG(uint a, uint b, uint c, uint d, uint x, int s)
{
uint t = a + ((b & (c | d)) | (c & d)) + x + 0x5A827999;
return t << s | t >> (32 - s);
}
private uint HH(uint a, uint b, uint c, uint d, uint x, int s)
{
uint t = a + (b ^ c ^ d) + x + 0x6ED9EBA1;
return t << s | t >> (32 - s);
}

} // class MD4
} // namespace Blood.COM.Security