C++ MD5的源码实例详解分享

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C++ MD5源码：

md5.h:

  #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*/     

md5.cpp:

  #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);   }   

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