C++ 计算某个文件的 MD5

1、头文件

#ifndef MD5_H 
#define MD5_H 

#include <string> 
#include <fstream> 

/* Type define */
typedef unsigned char byte;
typedef unsigned int uint32;
typedef unsigned int uint4;

using std::string;
using std::ifstream;

/* MD5 declaration. */
class MD5 {
public:
  MD5();
  MD5(const void *input, size_t length);
  MD5(const string &str);
  MD5(ifstream &in);
  void update(const void *input, size_t length);
  void update(const string &str);
  void update(ifstream &in);
  const byte* digest();
  string toString();
  void reset();

  inline uint4 rotate_left(uint4 x, int n);
  inline void FF(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
  inline void GG(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
  inline void HH(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);
  inline void II(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac);

private:
  void update(const byte *input, size_t length);
  void final();
  void transform(const byte block[64]);
  void encode(const uint32 *input, byte *output, size_t length);
  void decode(const byte *input, uint32 *output, size_t length);
  string bytesToHexString(const byte *input, size_t length);

  /* class uncopyable */
  MD5(const MD5&);
  MD5& operator=(const MD5&);
private:
  uint32 _state[4]; /* state (ABCD) */
  uint32 _count[2]; /* number of bits, modulo 2^64 (low-order word first) */
  byte _buffer[64]; /* input buffer */
  byte _digest[16]; /* message digest */
  bool _finished; /* calculate finished ? */

  static const byte PADDING[64]; /* padding for calculate */
  static const char HEX[16];
  static const size_t BUFFER_SIZE = 1024;
};

string FileDigest(const string &file);

#endif/*MD5_H*/

2、源文件

#include "md5.h" 

using namespace std;

/* 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 


/* 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)+ac; \
//(a) = ROTATE_LEFT((a), (s)); \
//(a) += (b); \
//}
//#define GG(a, b, c, d, x, s, ac) { \ 
//(a) += G((b), (c), (d)) + (x)+ac; \
//(a) = ROTATE_LEFT((a), (s)); \
//(a) += (b); \
//}
//#define HH(a, b, c, d, x, s, ac) { \ 
//(a) += H((b), (c), (d)) + (x)+ac; \
//(a) = ROTATE_LEFT((a), (s)); \
//(a) += (b); \
//}
//#define II(a, b, c, d, x, s, ac) { \ 
//(a) += I((b), (c), (d)) + (x)+ac; \
//(a) = ROTATE_LEFT((a), (s)); \
//(a) += (b); \
//}

inline uint4 MD5::rotate_left(uint4 x, int n) {
  return (x << n) | (x >> (32 - n));
}

inline void MD5::FF(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {
  a = rotate_left(a + F(b, c, d) + x + ac, s) + b;
}

inline void MD5::GG(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {
  a = rotate_left(a + G(b, c, d) + x + ac, s) + b;
}

inline void MD5::HH(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {
  a = rotate_left(a + H(b, c, d) + x + ac, s) + b;
}

inline void MD5::II(uint4 &a, uint4 b, uint4 c, uint4 d, uint4 x, uint4 s, uint4 ac) {
  a = rotate_left(a + I(b, c, d) + x + ac, s) + b;
}

const byte MD5::PADDING[64] = { 0x80 };
const char MD5::HEX[16] = {
  '0', '1', '2', '3',
  '4', '5', '6', '7',
  '8', '9', 'a', 'b',
  'c', 'd', 'e', 'f'
};

/* Default construct. */
MD5::MD5() {
  reset();
}

/* Construct a MD5 object with a input buffer. */
MD5::MD5(const void *input, size_t length) {
  reset();
  update(input, length);
}

/* Construct a MD5 object with a string. */
MD5::MD5(const string &str) {
  reset();
  update(str);
}

/* Construct a MD5 object with a file. */
MD5::MD5(ifstream &in) {
  reset();
  update(in);
}

/* Return the message-digest */
const byte* MD5::digest() {
  if (!_finished) {
    _finished = true;
    final();
  }
  return _digest;
}

/* Reset the calculate state */
void MD5::reset() {

  _finished = false;
  /* reset number of bits. */
  _count[0] = _count[1] = 0;
  /* Load magic initialization constants. */
  _state[0] = 0x67452301;
  _state[1] = 0xefcdab89;
  _state[2] = 0x98badcfe;
  _state[3] = 0x10325476;
}

/* Updating the context with a input buffer. */
void MD5::update(const void *input, size_t length) {
  update((const byte*)input, length);
}

/* Updating the context with a string. */
void MD5::update(const string &str) {
  update((const byte*)str.c_str(), str.length());
}

/* Updating the context with a file. */
void MD5::update(ifstream &in) {

  if (!in)
    return;

  std::streamsize length;
  char buffer[BUFFER_SIZE];
  while (!in.eof()) {
    in.read(buffer, BUFFER_SIZE);
    length = in.gcount();
    if (length > 0)
      update(buffer, length);
  }
  in.close();
}

/* MD5 block update operation. Continues an MD5 message-digest
operation, processing another message block, and updating the
context.
*/
void MD5::update(const byte *input, size_t length) {

  uint32 i, index, partLen;

  _finished = false;

  /* Compute number of bytes mod 64 */
  index = (uint32)((_count[0] >> 3) & 0x3f);

  /* update number of bits */
  if ((_count[0] += ((uint32)length << 3)) < ((uint32)length << 3))
    _count[1]++;
  _count[1] += ((uint32)length >> 29);

  partLen = 64 - index;

  /* transform as many times as possible. */
  if (length >= partLen) {

    memcpy(&_buffer[index], input, partLen);
    transform(_buffer);

    for (i = partLen; i + 63 < length; i += 64)
      transform(&input[i]);
    index = 0;

  }
  else {
    i = 0;
  }

  /* Buffer remaining input */
  memcpy(&_buffer[index], &input[i], length - i);
}

/* MD5 finalization. Ends an MD5 message-_digest operation, writing the
the message _digest and zeroizing the context.
*/
void MD5::final() {

  byte bits[8];
  uint32 oldState[4];
  uint32 oldCount[2];
  uint32 index, padLen;

  /* Save current state and count. */
  memcpy(oldState, _state, 16);
  memcpy(oldCount, _count, 8);

  /* Save number of bits */
  encode(_count, bits, 8);

  /* Pad out to 56 mod 64. */
  index = (uint32)((_count[0] >> 3) & 0x3f);
  padLen = (index < 56) ? (56 - index) : (120 - index);
  update(PADDING, padLen);

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

  /* Store state in digest */
  encode(_state, _digest, 16);

  /* Restore current state and count. */
  memcpy(_state, oldState, 16);
  memcpy(_count, oldCount, 8);
}

/* MD5 basic transformation. Transforms _state based on block. */
void MD5::transform(const byte block[64]) {

  uint32 a = _state[0], b = _state[1], c = _state[2], d = _state[3], x[16];

  decode(block, x, 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;
}

/* Encodes input (ulong) into output (byte). Assumes length is
a multiple of 4.
*/
void MD5::encode(const uint32 *input, byte *output, size_t length) {

  for (size_t i = 0, j = 0; j<length; i++, j += 4) {
    output[j] = (byte)(input[i] & 0xff);
    output[j + 1] = (byte)((input[i] >> 8) & 0xff);
    output[j + 2] = (byte)((input[i] >> 16) & 0xff);
    output[j + 3] = (byte)((input[i] >> 24) & 0xff);
  }
}

/* Decodes input (byte) into output (ulong). Assumes length is
a multiple of 4.
*/
void MD5::decode(const byte *input, uint32 *output, size_t length) {

  for (size_t i = 0, j = 0; j<length; i++, j += 4) {
    output[i] = ((uint32)input[j]) | (((uint32)input[j + 1]) << 8) |
      (((uint32)input[j + 2]) << 16) | (((uint32)input[j + 3]) << 24);
  }
}

/* Convert byte array to hex string. */
string MD5::bytesToHexString(const byte *input, size_t length) {
  string str;
  str.reserve(length << 1);
  for (size_t i = 0; i < length; i++) {
    int t = input[i];
    int a = t / 16;
    int b = t % 16;
    str.append(1, HEX[a]);
    str.append(1, HEX[b]);
  }
  return str;
}

/* Convert digest to string value */
string MD5::toString() {
  return bytesToHexString(digest(), 16);
}


//得到二进制文件的MD5码
string FileDigest(const string &file) {
  ifstream in(file.c_str(), ios::binary);
  if (!in)
    return "";

  MD5 md5;
  md5.reset();
  std::streamsize length;
  char buffer[1024];
  while (!in.eof()) {
    in.read(buffer, 1024);
    length = in.gcount();
    if (length > 0)
      md5.update(buffer, length);
  }
  in.close();
  return md5.toString();
}

3、测试代码

// Md5Test.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include "MD5.h"
#include <fstream>
#include <process.h>
int main()
{
  std::ifstream of("ReadMe.txt", std::ios::in | std::ios::binary);
  if (!of.is_open())return 0;
  MD5 fileMd5(of);
  printf("%s\r\n", fileMd5.toString().c_str());
  MD5 strMd5("123456789");
  printf("%s\r\n", strMd5.toString().c_str());
  system("pause");
  return 0;
}