/*
 * md4c.c	MD4 message-digest algorithm
 *
 *   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.
 *
 * Copyright 1990,1991,1992  RSA Data Security, Inc.
 */


#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 PROTO_LIST ((UINT4 [4], unsigned char [64]));
static void Encode PROTO_LIST
  ((unsigned char *, UINT4 *, unsigned int));
static void Decode PROTO_LIST
  ((UINT4 *, unsigned char *, unsigned int));
static void MD4_memcpy PROTO_LIST ((POINTER, POINTER, unsigned int));
static void MD4_memset PROTO_LIST ((POINTER, int, 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)); \
  }

void md4_calc(output, input, inlen)
unsigned char *output;
unsigned char *input;                                /* input block */
unsigned int inlen;                     /* length of input block */
{
	MD4_CTX	context;

	MD4Init(&context);
	MD4Update(&context, input, inlen);
	MD4Final(output, &context);
}

/* MD4 initialization. Begins an MD4 operation, writing a new context.
 */
void MD4Init (context)
MD4_CTX *context;                                        /* 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 (context, input, inputLen)
MD4_CTX *context;                                        /* context */
unsigned char *input;                                /* input block */
unsigned int inputLen;                     /* length of input block */
{
  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 (digest, context)
unsigned char digest[16];                         /* message digest */
MD4_CTX *context;                                        /* 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 (state, block)
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 (output, input, len)
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 (output, input, len)

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);
}

/* Note: Replace "for loop" with standard memcpy if possible.
 */
static void MD4_memcpy (output, input, len)
POINTER output;
POINTER input;
unsigned int len;
{
  unsigned int i;

  for (i = 0; i < len; i++)
    output[i] = input[i];
}

/* Note: Replace "for loop" with standard memset if possible.
 */
static void MD4_memset (output, value, len)
POINTER output;
int value;
unsigned int len;
{
  unsigned int i;

  for (i = 0; i < len; i++)
    ((char *)output)[i] = (char)value;
}
