md5.cc

/*********************************************************************
* Filename:   md5.c
* Author:     Brad Conte (brad AT bradconte.com)
* Copyright:
* Disclaimer: This code is presented "as is" without any guarantees.
* Details:    Implementation of the MD5 hashing algorithm.
                                  Algorithm specification can be found here:
                                   * http://tools.ietf.org/html/rfc1321
                                  This implementation uses little endian byte order.
*********************************************************************/

/*************************** HEADER FILES ***************************/
#include "md5.h"

#include <cstdio>
#include <cstdlib>
#include <cstring>

#include "sn3d.h"

/****************************** MACROS ******************************/
#define ROTLEFT(a, b) (((a) << (b)) | ((a) >> (32 - (b))))

#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 FF(a, b, c, d, m, s, t)    \
  {                                \
    (a) += F(b, c, d) + (m) + (t); \
    (a) = (b) + ROTLEFT(a, s);     \
  }
#define GG(a, b, c, d, m, s, t)    \
  {                                \
    (a) += G(b, c, d) + (m) + (t); \
    (a) = (b) + ROTLEFT(a, s);     \
  }
#define HH(a, b, c, d, m, s, t)     \
  {                                 \
    (a) += _H(b, c, d) + (m) + (t); \
    (a) = (b) + ROTLEFT(a, s);      \
  }
#define II(a, b, c, d, m, s, t)    \
  {                                \
    (a) += I(b, c, d) + (m) + (t); \
    (a) = (b) + ROTLEFT(a, s);     \
  }

/*********************** FUNCTION DEFINITIONS ***********************/
namespace {
void md5_transform(MD5_CTX *ctx, const BYTE data[]) {
  WORD a = 0;
  WORD b = 0;
  WORD c = 0;
  WORD d = 0;
  WORD m[16];
  WORD i = 0;
  WORD j = 0;

  // MD5 specifies big endian byte order, but this implementation assumes a little
  // endian byte order CPU. Reverse all the bytes upon input, and re-reverse them
  // on output (in md5_final()).
  for (i = 0, j = 0; i < 16; ++i, j += 4) {
    m[i] = (data[j]) + (data[j + 1] << 8) + (data[j + 2] << 16) + (data[j + 3] << 24);
  }

  a = ctx->state[0];
  b = ctx->state[1];
  c = ctx->state[2];
  d = ctx->state[3];

  FF(a, b, c, d, m[0], 7, 0xd76aa478);
  FF(d, a, b, c, m[1], 12, 0xe8c7b756);
  FF(c, d, a, b, m[2], 17, 0x242070db);
  FF(b, c, d, a, m[3], 22, 0xc1bdceee);
  FF(a, b, c, d, m[4], 7, 0xf57c0faf);
  FF(d, a, b, c, m[5], 12, 0x4787c62a);
  FF(c, d, a, b, m[6], 17, 0xa8304613);
  FF(b, c, d, a, m[7], 22, 0xfd469501);
  FF(a, b, c, d, m[8], 7, 0x698098d8);
  FF(d, a, b, c, m[9], 12, 0x8b44f7af);
  FF(c, d, a, b, m[10], 17, 0xffff5bb1);
  FF(b, c, d, a, m[11], 22, 0x895cd7be);
  FF(a, b, c, d, m[12], 7, 0x6b901122);
  FF(d, a, b, c, m[13], 12, 0xfd987193);
  FF(c, d, a, b, m[14], 17, 0xa679438e);
  FF(b, c, d, a, m[15], 22, 0x49b40821);

  GG(a, b, c, d, m[1], 5, 0xf61e2562);
  GG(d, a, b, c, m[6], 9, 0xc040b340);
  GG(c, d, a, b, m[11], 14, 0x265e5a51);
  GG(b, c, d, a, m[0], 20, 0xe9b6c7aa);
  GG(a, b, c, d, m[5], 5, 0xd62f105d);
  GG(d, a, b, c, m[10], 9, 0x02441453);
  GG(c, d, a, b, m[15], 14, 0xd8a1e681);
  GG(b, c, d, a, m[4], 20, 0xe7d3fbc8);
  GG(a, b, c, d, m[9], 5, 0x21e1cde6);
  GG(d, a, b, c, m[14], 9, 0xc33707d6);
  GG(c, d, a, b, m[3], 14, 0xf4d50d87);
  GG(b, c, d, a, m[8], 20, 0x455a14ed);
  GG(a, b, c, d, m[13], 5, 0xa9e3e905);
  GG(d, a, b, c, m[2], 9, 0xfcefa3f8);
  GG(c, d, a, b, m[7], 14, 0x676f02d9);
  GG(b, c, d, a, m[12], 20, 0x8d2a4c8a);

  HH(a, b, c, d, m[5], 4, 0xfffa3942);
  HH(d, a, b, c, m[8], 11, 0x8771f681);
  HH(c, d, a, b, m[11], 16, 0x6d9d6122);
  HH(b, c, d, a, m[14], 23, 0xfde5380c);
  HH(a, b, c, d, m[1], 4, 0xa4beea44);
  HH(d, a, b, c, m[4], 11, 0x4bdecfa9);
  HH(c, d, a, b, m[7], 16, 0xf6bb4b60);
  HH(b, c, d, a, m[10], 23, 0xbebfbc70);
  HH(a, b, c, d, m[13], 4, 0x289b7ec6);
  HH(d, a, b, c, m[0], 11, 0xeaa127fa);
  HH(c, d, a, b, m[3], 16, 0xd4ef3085);
  HH(b, c, d, a, m[6], 23, 0x04881d05);
  HH(a, b, c, d, m[9], 4, 0xd9d4d039);
  HH(d, a, b, c, m[12], 11, 0xe6db99e5);
  HH(c, d, a, b, m[15], 16, 0x1fa27cf8);
  HH(b, c, d, a, m[2], 23, 0xc4ac5665);

  II(a, b, c, d, m[0], 6, 0xf4292244);
  II(d, a, b, c, m[7], 10, 0x432aff97);
  II(c, d, a, b, m[14], 15, 0xab9423a7);
  II(b, c, d, a, m[5], 21, 0xfc93a039);
  II(a, b, c, d, m[12], 6, 0x655b59c3);
  II(d, a, b, c, m[3], 10, 0x8f0ccc92);
  II(c, d, a, b, m[10], 15, 0xffeff47d);
  II(b, c, d, a, m[1], 21, 0x85845dd1);
  II(a, b, c, d, m[8], 6, 0x6fa87e4f);
  II(d, a, b, c, m[15], 10, 0xfe2ce6e0);
  II(c, d, a, b, m[6], 15, 0xa3014314);
  II(b, c, d, a, m[13], 21, 0x4e0811a1);
  II(a, b, c, d, m[4], 6, 0xf7537e82);
  II(d, a, b, c, m[11], 10, 0xbd3af235);
  II(c, d, a, b, m[2], 15, 0x2ad7d2bb);
  II(b, c, d, a, m[9], 21, 0xeb86d391);

  ctx->state[0] += a;
  ctx->state[1] += b;
  ctx->state[2] += c;
  ctx->state[3] += d;
}

}  // anonymous namespace

void md5_init(MD5_CTX *ctx) {
  ctx->datalen = 0;
  ctx->bitlen = 0;
  ctx->state[0] = 0x67452301;
  ctx->state[1] = 0xEFCDAB89;
  ctx->state[2] = 0x98BADCFE;
  ctx->state[3] = 0x10325476;
}

void md5_update(MD5_CTX *ctx, const BYTE data[], size_t len) {
  size_t i = 0;

  for (i = 0; i < len; ++i) {
    ctx->data[ctx->datalen] = data[i];
    ctx->datalen++;
    if (ctx->datalen == 64) {
      md5_transform(ctx, ctx->data);
      ctx->bitlen += 512;
      ctx->datalen = 0;
    }
  }
}

void md5_final(MD5_CTX *ctx, BYTE hash[]) {
  size_t i = 0;

  i = ctx->datalen;

  // Pad whatever data is left in the buffer.
  if (ctx->datalen < 56) {
    ctx->data[i++] = 0x80;
    while (i < 56) {
      ctx->data[i++] = 0x00;
    }
  } else if (ctx->datalen >= 56) {
    ctx->data[i++] = 0x80;
    while (i < 64) {
      ctx->data[i++] = 0x00;
    }
    md5_transform(ctx, ctx->data);
    memset(ctx->data, 0, 56);
  }

  // Append to the padding the total message's length in bits and transform.
  ctx->bitlen += ctx->datalen * 8;
  ctx->data[56] = ctx->bitlen;
  ctx->data[57] = ctx->bitlen >> 8;
  ctx->data[58] = ctx->bitlen >> 16;
  ctx->data[59] = ctx->bitlen >> 24;
  ctx->data[60] = ctx->bitlen >> 32;
  ctx->data[61] = ctx->bitlen >> 40;
  ctx->data[62] = ctx->bitlen >> 48;
  ctx->data[63] = ctx->bitlen >> 56;
  md5_transform(ctx, ctx->data);

  // Since this implementation uses little endian byte ordering and MD uses big endian,
  // reverse all the bytes when copying the final state to the output hash.
  for (i = 0; i < 4; ++i) {
    hash[i] = (ctx->state[0] >> (i * 8)) & 0x000000ff;
    hash[i + 4] = (ctx->state[1] >> (i * 8)) & 0x000000ff;
    hash[i + 8] = (ctx->state[2] >> (i * 8)) & 0x000000ff;
    hash[i + 12] = (ctx->state[3] >> (i * 8)) & 0x000000ff;
  }
}

// added by Luke Shingles
void md5_file(const char filename[], char hashout[(2 * MD5_BLOCK_SIZE) + 1]) {
  MD5_CTX ctx;
  md5_init(&ctx);

  FILE *infile = fopen(filename, "r");

  assert_always(infile != nullptr);

  BYTE buffer[1024];

  size_t numbytes = 1;
  while (numbytes != 0 && feof(infile) == 0) {
    numbytes = fread(buffer, sizeof(char), 1024, infile);
    assert_always(ferror(infile) == 0);
    md5_update(&ctx, buffer, numbytes);
  }

  fclose(infile);

  BYTE hashbytes[MD5_BLOCK_SIZE];
  md5_final(&ctx, hashbytes);

  for (int j = 0; j < MD5_BLOCK_SIZE; j++) {
    snprintf(&hashout[2 * j], (2 * MD5_BLOCK_SIZE) + 1 - (2 * j), "%02x", hashbytes[j]);
  }

  hashout[2 * MD5_BLOCK_SIZE] = '\0';
}