/* 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char rcsid[] = "$OpenBSD: md4c.c,v 1.13 2002/02/16 21:27:23 millert Exp $";
#endif /* LIBC_SCCS and not lint */

#include <string.h>
#include <sys/types.h>
#include <md4.h>

/* POINTER defines a generic pointer type */
typedef unsigned char *POINTER;

/* 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

#if BYTE_ORDER == LITTLE_ENDIAN
#define Encode memcpy
#define Decode memcpy
#else /* BIG_ENDIAN */
static void Encode(void *, const void *, size_t);
static void Decode(void *, const void *, size_t);
#endif /* LITTLE_ENDIAN */

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) + (u_int32_t)0x5a827999; \
    (a) = ROTATE_LEFT ((a), (s)); \
  }
#define HH(a, b, c, d, x, s) { \
    (a) += H ((b), (c), (d)) + (x) + (u_int32_t)0x6ed9eba1; \
    (a) = ROTATE_LEFT ((a), (s)); \
  }

#if BYTE_ORDER != LITTLE_ENDIAN
/* Encodes input (u_int32_t) into output (unsigned char). Assumes len is
     a multiple of 4.
 */
static void Encode (out, in, len)
void *out;
const void *in;
size_t len;
{
  const u_int32_t *input = in;
  unsigned char *output = out;
  size_t 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 (u_int32_t). Assumes len is
     a multiple of 4.
 */
static void Decode (out, in, len)
void *out;
const void *in;
size_t len;
{
  u_int32_t *output = out;
  const unsigned char *input = in;
  size_t i, j;

  for (i = 0, j = 0; j < len; i++, j += 4)
    output[i] = ((u_int32_t)input[j]) | (((u_int32_t)input[j+1]) << 8) |
      (((u_int32_t)input[j+2]) << 16) | (((u_int32_t)input[j+3]) << 24);
}
#endif /* !LITTLE_ENDIAN */

/* MD4 initialization. Begins an MD4 operation, writing a new context.
 */
void MD4Init (context)
MD4_CTX *context;					 /* context */
{
  context->count = 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 (context, input, inputLen)
MD4_CTX *context;				/* context */
const unsigned char *input;			/* input block */
size_t inputLen;				/* length of input block */
{
  unsigned int i, index, partLen;

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

  /* Update number of bits */
  context->count += ((u_int64_t)inputLen << 3);

  partLen = 64 - index;
  /* Transform as many times as possible.  */
  if (inputLen >= partLen) {
    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 */
  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 (digest, context)
unsigned char digest[16];			  /* message digest */
MD4_CTX *context;					 /* context */
{
  unsigned char bits[8];
  unsigned int index, padLen;
  u_int32_t hi, lo;

  /* Save number of bits */
  hi = context->count >> 32;
  lo = (u_int32_t)context->count & 0xffffffff;
  Encode (bits, &lo, 4);
  Encode (bits + 4, &hi, 4);

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

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

  if (digest != NULL) {
    /* Store state in digest */
    Encode (digest, context->state, 16);

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

/* MD4 basic transformation. Transforms state based on block.
 */
void MD4Transform (state, block)
u_int32_t state[4];
const unsigned char block[64];
{
  u_int32_t 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.
   */
  memset ((POINTER)x, 0, sizeof (x));
}