md4c.c

/* MD4C.C - RSA Data Security, Inc., MD4 message-digest algorithm

   Copyright (C) 1990-2, RSA Data Security, Inc. All rights reserved.

   License to copy and use this software is granted provided that it
   is identified as the "RSA Data Security, Inc. MD4 Message-Digest
   Algorithm" in all material mentioning or referencing this software
   or this function.

   License is also granted to make and use derivative works provided
   that such works are identified as "derived from the RSA Data
   Security, Inc. MD4 Message-Digest Algorithm" in all material
   mentioning or referencing the derived work.

   RSA Data Security, Inc. makes no representations concerning either
   the merchantability of this software or the suitability of this
   software for any particular purpose. It is provided "as is"
   without express or implied warranty of any kind.

   These notices must be retained in any copies of any part of this
   documentation and/or software.
*/

#include <string.h>
#include "md4.h"

/* Constants for MD4Transform routine. */
#define S11 3
#define S12 7
#define S13 11
#define S14 19
#define S21 3
#define S22 5
#define S23 9
#define S24 13
#define S31 3
#define S32 9
#define S33 11
#define S34 15

static void MD4Transform( UINT4 [4], unsigned char [64] );
static void Encode( unsigned char *, UINT4 *, unsigned int );
static void Decode( UINT4 *, unsigned char *, unsigned int );

static unsigned char PADDING[64] = {
  0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

/* F, G and H are basic MD4 functions. */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (y)) | ((x) & (z)) | ((y) & (z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))

/* ROTATE_LEFT rotates x left n bits. */
#define ROTATE_LEFT(x, n) (((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.
*/
#define FF(a, b, c, d, x, s) { \
    (a) += F( (b), (c), (d) ) + (x); \
    (a) = ROTATE_LEFT( (a), (s) ); \
  }
#define GG(a, b, c, d, x, s) { \
    (a) += G( (b), (c), (d) ) + (x) + (UINT4)0x5a827999; \
    (a) = ROTATE_LEFT( (a), (s) ); \
  }
#define HH(a, b, c, d, x, s) { \
    (a) += H( (b), (c), (d) ) + (x) + (UINT4)0x6ed9eba1; \
    (a) = ROTATE_LEFT( (a), (s) ); \
  }

/* MD4_memcpy and MD4_memset are just memcpy and memset. */
#define MD4_memcpy(output, input, len ) \
  memcpy( output, input, len * sizeof( char ) );

#define MD4_memset(output, value, len ) \
  memset( output, value, len * sizeof( char ) );

/* MD4 initialization. Begins an MD4 operation, writing a new context. */
void
MD4Init( MD4_CTX *context )
{
  context->count[0] = context->count[1] = 0;

  /* Load magic initialization constants. */
  context->state[0] = 0x67452301;
  context->state[1] = 0xefcdab89;
  context->state[2] = 0x98badcfe;
  context->state[3] = 0x10325476;
}

/* MD4 block update operation. Continues an MD4 message-digest
   operation, processing another message block, and updating the
   context.
*/
void
MD4Update( MD4_CTX *context, unsigned char *input, unsigned int inputLen )
{
  unsigned int i, index, partLen;

  /* Compute number of bytes mod 64 */
  index = (unsigned int)((context->count[0] >> 3) & 0x3F);

  /* Update number of bits */
  if( (context->count[0] += ((UINT4)inputLen << 3)) < ((UINT4)inputLen << 3) )
    context->count[1]++;
  context->count[1] += ((UINT4)inputLen >> 29);

  partLen = 64 - index;

  /* Transform as many times as possible. */
  if( inputLen >= partLen )
    {
      MD4_memcpy( (POINTER)&context->buffer[index], (POINTER)input, partLen );
      MD4Transform( context->state, context->buffer );

      for( i = partLen; i + 63 < inputLen; i += 64 )
	MD4Transform( context->state, &input[i] );

      index = 0;
    }
  else
    i = 0;

  /* Buffer remaining input */
  MD4_memcpy( (POINTER)&context->buffer[index], (POINTER)&input[i], inputLen - i );
}

/* MD4 finalization. Ends an MD4 message-digest operation, writing the
   the message digest and zeroizing the context.
*/
void
MD4Final( unsigned char digest[16], MD4_CTX *context )
{
  unsigned char bits[8];
  unsigned int index, padLen;

  /* Save number of bits */
  Encode( bits, context->count, 8 );

  /* Pad out to 56 mod 64. */
  index = (unsigned int)((context->count[0] >> 3) & 0x3f);
  padLen = (index < 56) ? (56 - index) : (120 - index);
  MD4Update( context, PADDING, padLen );

  /* Append length (before padding) */
  MD4Update( context, bits, 8 );

  /* Store state in digest */
  Encode( digest, context->state, 16 );

  /* Zeroize sensitive information. */
  MD4_memset( (POINTER)context, 0, sizeof( *context ) );
}

/* MD4 basic transformation. Transforms state based on block. */
static void
MD4Transform( UINT4 state[4], unsigned char block[64] )
{
  UINT4 a = state[0], b = state[1], c = state[2], d = state[3], x[16];

  Decode( x, block, 64 );

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

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

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

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

  /* Zeroize sensitive information. */
  MD4_memset( (POINTER)x, 0, sizeof( x ) );
}

/* Encodes input (UINT4) into output (unsigned char). Assumes len is
   a multiple of 4.
*/
static void
Encode( unsigned char *output, UINT4 *input, unsigned int len )
{
  unsigned int i, j;

  for( i = 0, j = 0; j < len; i++, j += 4 )
    {
      output[j] = (unsigned char)(input[i] & 0xff);
      output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
      output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
      output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
    }
}

/* Decodes input (unsigned char) into output (UINT4). Assumes len is
   a multiple of 4.
*/
static void
Decode( UINT4 *output, unsigned char *input, unsigned int len )
{
  unsigned int i, j;

  for( i = 0, j = 0; j < len; i++, j += 4 )
    output[i] = ((UINT4)input[j]) | (((UINT4)input[j+1]) << 8) |
      (((UINT4)input[j+2]) << 16) | (((UINT4)input[j+3]) << 24);
}