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md5.c

/* taken from RFC-1321/Appendix A.3 */

/*
 * 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 <stdio.h>
#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 void MD5_memcpy(unsigned char *, unsigned char *, unsigned int);
static void MD5_memset(char *, 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, 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); \
}

/*
 * MD5 initialization. Begins an MD5 operation, writing a new context.
 */
void
MD5Init(MD5_CTX * context) {
      context->count[0] = 0;
      context->count[1] = 0;

      context->state[0] = 0x67452301;
      context->state[1] = 0xefcdab89;
      context->state[2] = 0x98badcfe;
      context->state[3] = 0x10325476;
}

void
MD5Update(MD5_CTX * context, unsigned char *input, unsigned int inputLen) {
      unsigned int i, index, partLen;

      index = (unsigned int) ((context->count[0] >> 3) & 0x3F);

      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;

      if (inputLen >= partLen) {
            MD5_memcpy(&context->buffer[index], 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;

      MD5_memcpy(&context->buffer[index], &input[i], inputLen - i);
}

void
MD5Final(unsigned char digest[16], MD5_CTX * context) {
      unsigned char bits[8];
      unsigned int index, padLen;

      Encode(bits, context->count, 8);

      index = (unsigned int) ((context->count[0] >> 3) & 0x3f);
      padLen = (index < 56) ? (56 - index) : (120 - index);
      MD5Update(context, PADDING, padLen);

      MD5Update(context, bits, 8);
      Encode(digest, context->state, 16);

      MD5_memset((char *) context, 0, sizeof(*context));
}

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;

      MD5_memset((char *) x, 0, sizeof(x));
}

/*
 * Encodes input (unsigned int) into output (unsigned char). Assumes len is a
 * multiple of 4.
 */
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);
      }
}

/*
 * Decodes input (unsigned char) into output (unsigned int). Assumes len is a
 * multiple of 4.
 */
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);
}

static void
MD5_memcpy(unsigned char *output, unsigned char *input, unsigned int len) {
      memcpy(output, input, len);
}

static void
MD5_memset(char *output, int value, unsigned int len) {
      memset(output, value, len);
}

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