C++ MD5的源码实例详解

#ifndef MD5_H #define MD5_H  #include <string> #include <fstream>  /* Type define */ typedef unsigned char byte; typedef unsigned int uint32;  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(); 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; };  #endif/*MD5_H*/ 

#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); / }   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); } 

#include "md5.h" #include <iostream>  using namespace std;  void PrintMD5(const string &str, MD5 &md5) {  cout << "MD5(/"" << str << "/") = " << md5.toString() << endl; }  string FileDigest(const string &file) {   ifstream in(file.c_str(), ios::binary);  if (!in)  return "";   MD5 md5;  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(); }  int main() {   cout << MD5("abc").toString() << endl;  cout << MD5(ifstream("D://test.txt")).toString() << endl;  cout << MD5(ifstream("D://test.exe", ios::binary)).toString() << endl;  cout << FileDigest("D://test.exe") << endl;   MD5 md5;  md5.update("");  PrintMD5("", md5);   md5.update("a");  PrintMD5("a", md5);   md5.update("bc");  PrintMD5("abc", md5);   md5.update("defghijklmnopqrstuvwxyz");  PrintMD5("abcdefghijklmnopqrstuvwxyz", md5);   md5.reset();  md5.update("message digest");  PrintMD5("message digest", md5);   md5.reset();  md5.update(ifstream("D://test.txt"));  PrintMD5("D://test.txt", md5);  return 0; } 

MD5();          //默认构造函数MD5(const void *input, size_t length);   //输入内存地址与长度信息的构造函数MD5(const string &str);      //输入字符串的构造函数MD5(ifstream &in);       //输入流的构造函数3个Update函数:void update(const void *input, size_t length); //往MD5对象内添加内存块void update(const string &str);    //添加字符串void update(ifstream &in);     //添加流const byte* digest();       //计算MD5码,并返回指向它的指针string toString();       //计算MD5,并返回其对应的字符串void reset();        //重置,