
/* MD5C.C - RSA Data Security, Inc., MD5 message-digest algorithm
 */

/* Copyright (C) 1991-2, RSA Data Security, Inc. Created 1991. All
   rights reserved.

   License to copy and use this software is granted provided that it
   is identified as the "RSA Data Security, Inc. MD5 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. MD5 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 "md5.h"

#include <string.h>

/* Constants for MD5Transform routine.
 */
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21

static const 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, H and I are basic MD5 functions.
 */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z)))

/* ROTATE_LEFT rotates x left n bits.
 */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
   Rotation is separate from addition to prevent recomputation.
 */
#define FF(a, b, c, d, x, s, ac) { \
    (a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
    (a) = ROTATE_LEFT ((a), (s)); \
    (a) += (b); \
  }
#define GG(a, b, c, d, x, s, ac) { \
    (a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
    (a) = ROTATE_LEFT ((a), (s)); \
    (a) += (b); \
  }
#define HH(a, b, c, d, x, s, ac) { \
    (a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
    (a) = ROTATE_LEFT ((a), (s)); \
    (a) += (b); \
  }
#define II(a, b, c, d, x, s, ac) { \
    (a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
    (a) = ROTATE_LEFT ((a), (s)); \
    (a) += (b); \
  }

#define MD5_memcpy(dst, src, len) memcpy((dst), (src), (len))
#define MD5_memset(dst, val, len) memset((dst), (val), (len))

/* 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, const 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);
}

/* MD5 basic transformation. Transforms state based on block.
 */
static void
MD5Transform(UINT4 state[4], const 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, 0xd76aa478);        /* 1 */
  FF(d, a, b, c, x[1], S12, 0xe8c7b756);        /* 2 */
  FF(c, d, a, b, x[2], S13, 0x242070db);        /* 3 */
  FF(b, c, d, a, x[3], S14, 0xc1bdceee);        /* 4 */
  FF(a, b, c, d, x[4], S11, 0xf57c0faf);        /* 5 */
  FF(d, a, b, c, x[5], S12, 0x4787c62a);        /* 6 */
  FF(c, d, a, b, x[6], S13, 0xa8304613);        /* 7 */
  FF(b, c, d, a, x[7], S14, 0xfd469501);        /* 8 */
  FF(a, b, c, d, x[8], S11, 0x698098d8);        /* 9 */
  FF(d, a, b, c, x[9], S12, 0x8b44f7af);        /* 10 */
  FF(c, d, a, b, x[10], S13, 0xffff5bb1);       /* 11 */
  FF(b, c, d, a, x[11], S14, 0x895cd7be);       /* 12 */
  FF(a, b, c, d, x[12], S11, 0x6b901122);       /* 13 */
  FF(d, a, b, c, x[13], S12, 0xfd987193);       /* 14 */
  FF(c, d, a, b, x[14], S13, 0xa679438e);       /* 15 */
  FF(b, c, d, a, x[15], S14, 0x49b40821);       /* 16 */

  /* Round 2 */
  GG(a, b, c, d, x[1], S21, 0xf61e2562);        /* 17 */
  GG(d, a, b, c, x[6], S22, 0xc040b340);        /* 18 */
  GG(c, d, a, b, x[11], S23, 0x265e5a51);       /* 19 */
  GG(b, c, d, a, x[0], S24, 0xe9b6c7aa);        /* 20 */
  GG(a, b, c, d, x[5], S21, 0xd62f105d);        /* 21 */
  GG(d, a, b, c, x[10], S22, 0x2441453);        /* 22 */
  GG(c, d, a, b, x[15], S23, 0xd8a1e681);       /* 23 */
  GG(b, c, d, a, x[4], S24, 0xe7d3fbc8);        /* 24 */
  GG(a, b, c, d, x[9], S21, 0x21e1cde6);        /* 25 */
  GG(d, a, b, c, x[14], S22, 0xc33707d6);       /* 26 */
  GG(c, d, a, b, x[3], S23, 0xf4d50d87);        /* 27 */
  GG(b, c, d, a, x[8], S24, 0x455a14ed);        /* 28 */
  GG(a, b, c, d, x[13], S21, 0xa9e3e905);       /* 29 */
  GG(d, a, b, c, x[2], S22, 0xfcefa3f8);        /* 30 */
  GG(c, d, a, b, x[7], S23, 0x676f02d9);        /* 31 */
  GG(b, c, d, a, x[12], S24, 0x8d2a4c8a);       /* 32 */

  /* Round 3 */
  HH(a, b, c, d, x[5], S31, 0xfffa3942);        /* 33 */
  HH(d, a, b, c, x[8], S32, 0x8771f681);        /* 34 */
  HH(c, d, a, b, x[11], S33, 0x6d9d6122);       /* 35 */
  HH(b, c, d, a, x[14], S34, 0xfde5380c);       /* 36 */
  HH(a, b, c, d, x[1], S31, 0xa4beea44);        /* 37 */
  HH(d, a, b, c, x[4], S32, 0x4bdecfa9);        /* 38 */
  HH(c, d, a, b, x[7], S33, 0xf6bb4b60);        /* 39 */
  HH(b, c, d, a, x[10], S34, 0xbebfbc70);       /* 40 */
  HH(a, b, c, d, x[13], S31, 0x289b7ec6);       /* 41 */
  HH(d, a, b, c, x[0], S32, 0xeaa127fa);        /* 42 */
  HH(c, d, a, b, x[3], S33, 0xd4ef3085);        /* 43 */
  HH(b, c, d, a, x[6], S34, 0x4881d05); /* 44 */
  HH(a, b, c, d, x[9], S31, 0xd9d4d039);        /* 45 */
  HH(d, a, b, c, x[12], S32, 0xe6db99e5);       /* 46 */
  HH(c, d, a, b, x[15], S33, 0x1fa27cf8);       /* 47 */
  HH(b, c, d, a, x[2], S34, 0xc4ac5665);        /* 48 */

  /* Round 4 */
  II(a, b, c, d, x[0], S41, 0xf4292244);        /* 49 */
  II(d, a, b, c, x[7], S42, 0x432aff97);        /* 50 */
  II(c, d, a, b, x[14], S43, 0xab9423a7);       /* 51 */
  II(b, c, d, a, x[5], S44, 0xfc93a039);        /* 52 */
  II(a, b, c, d, x[12], S41, 0x655b59c3);       /* 53 */
  II(d, a, b, c, x[3], S42, 0x8f0ccc92);        /* 54 */
  II(c, d, a, b, x[10], S43, 0xffeff47d);       /* 55 */
  II(b, c, d, a, x[1], S44, 0x85845dd1);        /* 56 */
  II(a, b, c, d, x[8], S41, 0x6fa87e4f);        /* 57 */
  II(d, a, b, c, x[15], S42, 0xfe2ce6e0);       /* 58 */
  II(c, d, a, b, x[6], S43, 0xa3014314);        /* 59 */
  II(b, c, d, a, x[13], S44, 0x4e0811a1);       /* 60 */
  II(a, b, c, d, x[4], S41, 0xf7537e82);        /* 61 */
  II(d, a, b, c, x[11], S42, 0xbd3af235);       /* 62 */
  II(c, d, a, b, x[2], S43, 0x2ad7d2bb);        /* 63 */
  II(b, c, d, a, x[9], S44, 0xeb86d391);        /* 64 */

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

  /* Zeroize sensitive information.
   */
  MD5_memset((POINTER) x, 0, sizeof(x));
}

/* MD5 initialization. Begins an MD5 operation, writing a new context.
 */
void
MD5Init(MD5_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;
}

/* MD5 block update operation. Continues an MD5 message-digest
     operation, processing another message block, and updating the
     context.
 */
void
MD5Update(MD5_CTX * context, const unsigned char *input, const unsigned int inputLen)
{
  unsigned int i, idx, partLen;

  /* Compute number of bytes mod 64 */
  idx = (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 - idx;

  /* Transform as many times as possible.
   */
  if (inputLen >= partLen) {
    MD5_memcpy((POINTER) & context->buffer[idx], input, partLen);
    MD5Transform(context->state, context->buffer);

    for (i = partLen; i + 63 < inputLen; i += 64)
      MD5Transform(context->state, &input[i]);

    idx = 0;
  } else
    i = 0;

  /* Buffer remaining input */
  MD5_memcpy((POINTER) & context->buffer[idx], &input[i], inputLen - i);
}

/* MD5 finalization. Ends an MD5 message-digest operation, writing the
     the message digest and zeroizing the context.
 */
void
MD5Final(unsigned char digest[16], MD5_CTX * context)
{
  unsigned char bits[8];
  unsigned int idx, padLen;

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

  /* Pad out to 56 mod 64.
   */
  idx = (unsigned int)((context->count[0] >> 3) & 0x3f);
  padLen = (idx < 56) ? (56 - idx) : (120 - idx);
  MD5Update(context, PADDING, padLen);

  /* Append length (before padding) */
  MD5Update(context, bits, 8);

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

  /* Zeroize sensitive information.
   */
  MD5_memset((POINTER) context, 0, sizeof(*context));
}

/*
 * Local Variables:
 * c-basic-offset: 2
 * indent-tabs-mode: nil
 * End:
 */
