/*
 *    Copyright (C) 2001 Nikos Mavroyanopoulos
 *
 *    This library is free software; you can redistribute it and/or
 *    modify it under the terms of the GNU Library General Public
 *    License as published by the Free Software Foundation; either
 *    version 2 of the License, or (at your option) any later version.
 *
 *    This library is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Library General Public License for more details.
 *
 *    You should have received a copy of the GNU Library General
 *    Public License along with this library; if not, write to the
 *    Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 *    Boston, MA 02110-1301, USA
 */


#include "global.h"

/* 
 * The algorithm is due to Ron Rivest.  This code is based on code
 * written by Colin Plumb in 1993.
 */


/*
 * This code implements the MD4 message-digest algorithm.
 */

#include "md4.h"

#ifndef WORDS_BIGENDIAN
#define byteReverse(buf, len)	/* Nothing */
#else
static void byteReverse (unsigned char *buf, unsigned longs);


/*
 * Note: this code is harmless on little-endian machines.
 */
static void
byteReverse (unsigned char *buf, unsigned longs)
{
  word32 t;
  do
    {
#if 0
      t = (word32) ((unsigned) buf[3] << 8 | buf[2]) << 16 |
	((unsigned) buf[1] << 8 | buf[0]);
      *(word32 *) buf = t;
#else
      *(word32 *) buf = byteswap32 (*(word32 *) buf);
#endif
      buf += 4;
    }
  while (--longs);
}
#endif

/*
 * Start MD4 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
NTLM_STATIC void
MD4Init (struct MD4Context *ctx)
{
  ctx->buf[0] = 0x67452301;
  ctx->buf[1] = 0xefcdab89;
  ctx->buf[2] = 0x98badcfe;
  ctx->buf[3] = 0x10325476;

  ctx->bits[0] = 0;
  ctx->bits[1] = 0;
}

/*
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
NTLM_STATIC void
MD4Update (struct MD4Context *ctx, unsigned char const *buf, unsigned len)
{
  register word32 t;

  /* Update bitcount */

  t = ctx->bits[0];
  if ((ctx->bits[0] = t + ((word32) len << 3)) < t)
    ctx->bits[1]++;		/* Carry from low to high */
  ctx->bits[1] += len >> 29;

  t = (t >> 3) & 0x3f;		/* Bytes already in shsInfo->data */

  /* Handle any leading odd-sized chunks */

  if (t)
    {
      unsigned char *p = (unsigned char *) ctx->in + t;

      t = 64 - t;
      if (len < t)
	{
	  memcpy (p, buf, len);
	  return;
	}
      memcpy (p, buf, t);
      byteReverse (ctx->in, 16);
      MD4Transform (ctx->buf, (word32 *) ctx->in);
      buf += t;
      len -= t;
    }
  /* Process data in 64-byte chunks */

  while (len >= 64)
    {
      memcpy (ctx->in, buf, 64);
      byteReverse (ctx->in, 16);
      MD4Transform (ctx->buf, (word32 *) ctx->in);
      buf += 64;
      len -= 64;
    }

  /* Handle any remaining bytes of data. */

  memcpy (ctx->in, buf, len);
}

/*
 * Final wrapup - pad to 64-byte boundary with the bit pattern 
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
NTLM_STATIC void
MD4Final (struct MD4Context *ctx, unsigned char *digest)
{
  unsigned int count;
  unsigned char *p;

  /* Compute number of bytes mod 64 */
  count = (ctx->bits[0] >> 3) & 0x3F;

  /* Set the first char of padding to 0x80.  This is safe since there is
     always at least one byte free */
  p = ctx->in + count;
  *p++ = 0x80;

  /* Bytes of padding needed to make 64 bytes */
  count = 64 - 1 - count;

  /* Pad out to 56 mod 64 */
  if (count < 8)
    {
      /* Two lots of padding:  Pad the first block to 64 bytes */
      memset (p, 0, count);
      byteReverse (ctx->in, 16);
      MD4Transform (ctx->buf, (word32 *) ctx->in);

      /* Now fill the next block with 56 bytes */
      memset (ctx->in, 0, 56);
    }
  else
    {
      /* Pad block to 56 bytes */
      memset (p, 0, count - 8);
    }
  byteReverse (ctx->in, 14);

  /* Append length in bits and transform */
  ((word32 *) ctx->in)[14] = ctx->bits[0];
  ((word32 *) ctx->in)[15] = ctx->bits[1];

  MD4Transform (ctx->buf, (word32 *) ctx->in);
  byteReverse ((unsigned char *) ctx->buf, 4);

  if (digest != NULL)
    memcpy (digest, ctx->buf, 16);
  memset (ctx, 0, sizeof (ctx));	/* In case it's sensitive */
}

/* The three core 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))

#define FF(a, b, c, d, x, s) { \
    (a) += F ((b), (c), (d)) + (x); \
    (a) = rotl32 ((a), (s)); \
  }
#define GG(a, b, c, d, x, s) { \
    (a) += G ((b), (c), (d)) + (x) + (word32)0x5a827999; \
    (a) = rotl32 ((a), (s)); \
  }
#define HH(a, b, c, d, x, s) { \
    (a) += H ((b), (c), (d)) + (x) + (word32)0x6ed9eba1; \
    (a) = rotl32 ((a), (s)); \
  }


/*
 * The core of the MD4 algorithm
 */
NTLM_STATIC void
MD4Transform (word32 buf[4], word32 const in[16])
{
  register word32 a, b, c, d;

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

  FF (a, b, c, d, in[0], 3);	/* 1 */
  FF (d, a, b, c, in[1], 7);	/* 2 */
  FF (c, d, a, b, in[2], 11);	/* 3 */
  FF (b, c, d, a, in[3], 19);	/* 4 */
  FF (a, b, c, d, in[4], 3);	/* 5 */
  FF (d, a, b, c, in[5], 7);	/* 6 */
  FF (c, d, a, b, in[6], 11);	/* 7 */
  FF (b, c, d, a, in[7], 19);	/* 8 */
  FF (a, b, c, d, in[8], 3);	/* 9 */
  FF (d, a, b, c, in[9], 7);	/* 10 */
  FF (c, d, a, b, in[10], 11);	/* 11 */
  FF (b, c, d, a, in[11], 19);	/* 12 */
  FF (a, b, c, d, in[12], 3);	/* 13 */
  FF (d, a, b, c, in[13], 7);	/* 14 */
  FF (c, d, a, b, in[14], 11);	/* 15 */
  FF (b, c, d, a, in[15], 19);	/* 16 */

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

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


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