md5.c

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/*
 * $Id: md5.c 4972 2008-09-22 17:06:17Z henningw $
 *
 * 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.
 */

/*!
 * \file
 * \brief MD5 message-digest algorithm - RSA Data Security, Inc.
 */


#include <string.h>
#include "md5.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 void MD5Transform (unsigned int [4], unsigned char [64]);
static void Encode (unsigned char *, unsigned int *, unsigned int);
static void Decode (unsigned int *, 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, 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) + (unsigned int)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
}
#define GG(a, b, c, d, x, s, ac) { \
   (a) += G ((b), (c), (d)) + (x) + (unsigned int)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
}
#define HH(a, b, c, d, x, s, ac) { \
   (a) += H ((b), (c), (d)) + (x) + (unsigned int)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
}
#define II(a, b, c, d, x, s, ac) { \
   (a) += I ((b), (c), (d)) + (x) + (unsigned int)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
}


/*!
 * \brief MD5 initialization. Begins an MD5 operation, writing a new context.
 * \param context MD5 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;
}


/*!
 * \brief MD5 block update operation.
 *
 * MD5 block update operation. Continues an MD5 message-digest
 * operation, processing another message block, and updating the
 * context.
 * \param context MD5 context
 * \param input input block
 * \param inputLen length of input block
 */
void U_MD5Update (MD5_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] += ((unsigned int)inputLen << 3)) < ((unsigned int)inputLen << 3))
      context->count[1]++;

   context->count[1] += ((unsigned int)inputLen >> 29);
   partLen = 64 - index;

   /* Transform as many times as possible. */
   if (inputLen >= partLen) {
      memcpy((unsigned char *)&context->buffer[index], (unsigned char *)input, partLen);
      MD5Transform (context->state, context->buffer);

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

      index = 0;
   }
   else
      i = 0;

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


/*!
 * \brief MD5 finalization
 *
 * MD5 finalization. Ends an MD5 message-digest operation, writing the
 * the message digest and zeroizing the context.
 * \param digest message digest
 * \param context MD5 context
 */
void U_MD5Final (unsigned char digest[16], MD5_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);
   U_MD5Update (context, PADDING, padLen);

   /* Append length (before padding) */
   U_MD5Update (context, bits, 8);

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

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


/*!
 * \brief MD5 basic transformation. Transforms state based on block.
 * \param state transformed state
 * \param block input block
 */
static void MD5Transform (unsigned int state[4], unsigned char block[64])
{
   unsigned int 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. */
   memset ((unsigned char *)x, 0, sizeof (x));
}


/*!
 * \brief Encodes input (unsigned int) into output (unsigned char).
 * \note Assumes len is a multiple of 4.
 * \param output output character
 * \param input input
 * \param len length
 */
static void Encode (unsigned char *output, unsigned int *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);
   }
}


/*!
 * \brief Decodes input (unsigned char) into output (unsigned int).
 * \note Assumes len is a multiple of 4.
 * \param output output character
 * \param input input
 * \param len length
 */
static void Decode (unsigned int *output, unsigned char *input, unsigned int len)
{
   unsigned int i, j;

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

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