text: /* ===================================================================
   *
   * Copyright (c) 2018, Helder Eijs <helderijs@gmail.com>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   * ===================================================================
   */
  
  #include "common.h"
  #include <stdio.h>
  
  FAKE_INIT(MD5)
  
  /**
   * MD5 as defined in RFC1321
   */
  
  #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)))
  
  #define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
  
  #define FF(a, b, c, d, x, s, ac) { \
   (a) += F ((b), (c), (d)) + (x) + (uint32_t)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
   }
  
  #define GG(a, b, c, d, x, s, ac) { \
   (a) += G ((b), (c), (d)) + (x) + (uint32_t)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
   }
  
  #define HH(a, b, c, d, x, s, ac) { \
   (a) += H ((b), (c), (d)) + (x) + (uint32_t)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
   }
  
  #define II(a, b, c, d, x, s, ac) { \
   (a) += I ((b), (c), (d)) + (x) + (uint32_t)(ac); \
   (a) = ROTATE_LEFT ((a), (s)); \
   (a) += (b); \
   }
  
  #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
  
  #define BLOCK_SIZE 64
  
  #define DIGEST_SIZE (128/8)
  
  typedef struct t_hash_state {
      uint32_t h[4];
      uint8_t buf[BLOCK_SIZE];    /** 64 bytes == 512 bits == sixteen 32-bit words **/
      unsigned curlen;            /** Useful message bytes in buf[] (leftmost) **/
      uint64_t totbits;           /** Total message length in bits **/
  } hash_state;
  
  static int add_bits(hash_state *hs, unsigned bits)
  {
      /** Maximum message length for MD5 is 2**64 bits **/
      hs->totbits += bits;
      return (hs->totbits < bits) ? ERR_MAX_DATA : 0;
  }
  
  static void md5_compress(hash_state * hs)
  {
      uint32_t a, b, c, d;
      uint32_t x[16];
      int i;
  
      /** Words flow in in little-endian mode **/
      for (i=0; i<16; i++) {
          x[i] = LOAD_U32_LITTLE(&hs->buf[i*4]);
      }
  
      a = hs->h[0];
      b = hs->h[1];
      c = hs->h[2];
      d = hs->h[3];
    
  	/* 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 */
  
      /** compute new intermediate hash **/
      hs->h[0] += a;
      hs->h[1] += b;
      hs->h[2] += c;
      hs->h[3] += d;
  }
  
  EXPORT_SYM int MD5_init(hash_state **mdState)
  {
      hash_state *hs;
  
      if (NULL == mdState) {
          return ERR_NULL;
      }
  
      *mdState = hs = (hash_state*) calloc(1, sizeof(hash_state));
      if (NULL == hs)
          return ERR_MEMORY;
  
      hs->curlen = 0;
      hs->totbits = 0;
  
      /** Initial intermediate hash value **/
      hs->h[0] = 0x67452301;
      hs->h[1] = 0xefcdab89;
      hs->h[2] = 0x98badcfe;
      hs->h[3] = 0x10325476;
  
      return 0;
  }
  
  EXPORT_SYM int MD5_destroy (hash_state *mdState)
  {
      free(mdState);
      return 0;
  }
  
  EXPORT_SYM int MD5_update(hash_state *hs, const uint8_t *buf, size_t len)
  {
      if (NULL == hs || NULL == buf) {
          return ERR_NULL;
      }
  
      assert(hs->curlen < BLOCK_SIZE);
  
      while (len>0) {
          unsigned left, btc;
  
          left = BLOCK_SIZE - hs->curlen;
          btc = (unsigned)MIN(left, len);
          memcpy(&hs->buf[hs->curlen], buf, btc);
          buf += btc;
          hs->curlen += btc;
          len -= btc;
  
          if (hs->curlen == BLOCK_SIZE) {
              md5_compress(hs);
              hs->curlen = 0;
              if (add_bits(hs, BLOCK_SIZE*8)) {
                  return ERR_MAX_DATA;
              }
          }
      }
  
      return 0;
  }
  
  static int md5_finalize(hash_state *hs, uint8_t *hash /** [DIGEST_SIZE] **/)
  {
      unsigned left, i;
  
      assert(hs->curlen < BLOCK_SIZE);
  
      /* remaining length of the message */
      if (add_bits(hs, hs->curlen*8)) {
          return ERR_MAX_DATA;
      }
  
      /* append the '1' bit */
      /* buf[] is guaranteed to have at least 1 byte free */
      hs->buf[hs->curlen++] = 0x80;
  
      /** if there are less then 64 bits lef, just pad with zeroes and compress **/
      left = BLOCK_SIZE - hs->curlen;
      if (left < 8) {
          memset(&hs->buf[hs->curlen], 0, left);
          md5_compress(hs);
          hs->curlen = 0;
      }
  
      /**
       * pad with zeroes and close the block with the bit length
       * encoded as 64-bit integer little endian.
       **/
      left = BLOCK_SIZE - hs->curlen;
      memset(&hs->buf[hs->curlen], 0, left);
      STORE_U64_LITTLE(&hs->buf[BLOCK_SIZE-8], hs->totbits);
  
      /** compress one last time **/
      md5_compress(hs);
  
      /** create final hash **/
      for (i=0; i<4; i++) {
          STORE_U32_LITTLE(&hash[i*4], hs->h[i]);
      }
  
      return 0;
  }
  
  EXPORT_SYM int MD5_digest(const hash_state *mdState, uint8_t digest[DIGEST_SIZE])
  {
      hash_state temp;
  
      if (NULL == mdState) {
          return ERR_NULL;
      }
  
      temp = *mdState;
      md5_finalize(&temp, digest);
      return 0;
  }
  
  EXPORT_SYM int MD5_copy(const hash_state *src, hash_state *dst)
  {
      if (NULL == src || NULL == dst) {
          return ERR_NULL;
      }
  
      *dst = *src;
      return 0;
  }
  
  /**
   * This is a specialized function to efficiently perform the inner loop of PBKDF2-HMAC.
   *
   * - inner, the hash after the inner padded secret has been absorbed
   * - outer, the hash after the outer padded secret has been absorbed
   * - first_hmac, the output of the first HMAC iteration (with salt and counter)
   * - result, the XOR of the HMACs from all iterations
   * - iterations, the total number of PBKDF2 iterations (>0)
   *
   * This function does not change the state of either hash.
   */
  EXPORT_SYM int MD5_pbkdf2_hmac_assist(const hash_state *inner, const hash_state *outer,
                                               const uint8_t first_hmac[DIGEST_SIZE],
                                               uint8_t result[DIGEST_SIZE],
                                               size_t iterations)
  {
      hash_state inner_temp, outer_temp;
      size_t i;
      uint8_t last_hmac[DIGEST_SIZE];
  
      if (NULL == inner || NULL == outer || NULL == first_hmac || NULL == result) {
          return ERR_NULL;
      }
  
      if (iterations == 0) {
          return ERR_NR_ROUNDS;
      }
  
      memcpy(result, first_hmac, DIGEST_SIZE);
      memcpy(last_hmac, first_hmac, DIGEST_SIZE);
  
      for (i=1; i<iterations; i++) {
          int j;
  
          inner_temp = *inner;
          outer_temp = *outer;
  
          MD5_update(&inner_temp, last_hmac, DIGEST_SIZE);
          md5_finalize(&inner_temp, last_hmac);
  
          /** last_hmac is now the intermediate digest **/
  
          MD5_update(&outer_temp, last_hmac, DIGEST_SIZE);
          md5_finalize(&outer_temp, last_hmac);
  
          for (j=0; j<DIGEST_SIZE; j++) {
              result[j] ^= last_hmac[j];
          }
      }
  
      return 0;
  }
  
  #ifdef MAIN
  int main(void)
  {
      hash_state *hs;
      const uint8_t tv[] = "The quick brown fox jumps over the lazy dog";
      uint8_t result[DIGEST_SIZE];
      int i;
  
      MD5_init(&hs);
      MD5_update(hs, tv, sizeof tv - 1);
      MD5_digest(hs, result);
      MD5_destroy(hs);
  
      for (i=0; i<sizeof result; i++) {
          printf("%02X", result[i]);
      }
      printf("\n");
  
      MD5_init(&hs);
      MD5_digest(hs, result);
      MD5_destroy(hs);
  
      for (i=0; i<sizeof result; i++) {
          printf("%02X", result[i]);
      }
      printf("\n");
  
      MD5_init(&hs);
      for (i=0; i<10000000; i++) {
          MD5_update(hs, tv, sizeof tv - 1);
      }
      MD5_destroy(hs);
  
      printf("\n");
  }
  #endif
  