与java一致的md5算法（C++）

工作中需要对网络传输的二进制配置文件进行md5运算生成校验码，以避免在网络传输中，文件的内容发生损坏和篡改。过程中大致是这样的：

 1.服务端c++，请求端java；

 2.请求端POST请求服务器上的某个文件，要求传输到请求端；

 3.向服务端请求文件时，服务端需要对要传输的文件内容作md5加密，生成32字符校验码，将校验码作为http头信息字段传输到请求端；

 4.请求端对传过来的文件也进行MD5加密，生成的校验码和服务器传来的做比较，相同即保证了数据的完整性和合法性，并对内容进行处理，否则，丢弃。

遇到的问题：需要保证请求端和服务器的md5算法一致，而往往C++和java的md5算法有多种，这里我们采用C++依照java的md5算法来实现，即用与java的MD5算法一致的C++算法来解决。

代码链接来源：http://blog.csdn.net/beyondhaven/article/details/8275110（谢谢BeyondHaven^_^）

MD5.h

#ifndef _DMSUTIL_H
#define _DMSUTIL_H
#ifdef __cplusplus
extern "C" {
#endif
    /*————————————————————————.
    | md5 encrypt function
    .————————————————————————*/
    void EncryptMD5(unsigned char *output, unsigned char *input);
    void EncryptMD5str(char *output, unsigned char *input, int len);
    /*————————————————————————.
    | hash encrypt function
    .————————————————————————*/
    void EncryptHash(char *crypt, char *source);
    /*————————————————————————.
    | DES encrypt and decrypt function
    .————————————————————————*/
    void EncryptDes(unsigned char *source, unsigned char *encrypt);
    void DecryptDes(unsigned char *encrypt, unsigned char *source);
#ifdef __cplusplus
}
#endif
#endif

MD5.cpp

#include <stdio.h>
#include <string.h>
#include "MD5Encrypt.h"
/*MD5 context*/
typedef struct MD5_CTX_S{
    unsigned int state[4];
    unsigned int count[2];
    char buffer[64];
}MD5_CTX;

static unsigned char digest[16];
/*MD5 initialization*/
static void MD5Init(MD5_CTX *);
/*MD5 block update operation*/
static void MD5Update(MD5_CTX *, unsigned char *, unsigned int);
/*Ends an MD5 message-digest operation*/
static void MD5Final(unsigned char [16], MD5_CTX *);
/*MD5 padding*/
static void   __md5_Pad (MD5_CTX *);
/*MD5 basic transformation*/
static void   __md5_Transform (unsigned int [4], unsigned char [64]);
#ifdef i386
#define __md5_Encode memcpy
#define __md5_Decode memcpy
#else /* i386 */
/*
* __md5_Encodes input (u_int32_t) into output (unsigned char). Assumes len is
* a multiple of 4.
*/
static void
__md5_Encode (unsigned char *output, unsigned int *input, unsigned int len)
{
    unsigned int i, j;
    for (i = 0, j = 0; j < len; i++, j += 4) {
        output[j] = (unsigned char)(input[i] & 0xff);
        output[j+1] = (unsigned char)((input[i] >> 8) & 0xff);
        output[j+2] = (unsigned char)((input[i] >> 16) & 0xff);
        output[j+3] = (unsigned char)((input[i] >> 24) & 0xff);
    }
}
/*
* __md5_Decodes input (unsigned char) into output (u_int32_t). Assumes len is
* a multiple of 4.
*/
static void
__md5_Decode (unsigned int  *output, unsigned char *input, unsigned int len)
{
    unsigned int i, j;
    for (i = 0, j = 0; j < len; i++, j += 4)
        output[i] = ((unsigned int)input[j]) | (((unsigned int)input[j+1]) << 8) |
        (((unsigned int)input[j+2]) << 16) | (((unsigned int)input[j+3]) << 24);
}
#endif /* i386 */
/* 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) + (unsigned int)(ac); 
    (a) = ROTATE_LEFT ((a), (s)); 
    (a) += (b); 
}
#define GG(a, b, c, d, x, s, ac) { 
    (a) += G ((b), (c), (d)) + (x) + (unsigned int)(ac); 
    (a) = ROTATE_LEFT ((a), (s)); 
    (a) += (b); 
}
#define HH(a, b, c, d, x, s, ac) { 
    (a) += H ((b), (c), (d)) + (x) + (unsigned int)(ac); 
    (a) = ROTATE_LEFT ((a), (s)); 
    (a) += (b); 
}
#define II(a, b, c, d, x, s, ac) { 
    (a) += I ((b), (c), (d)) + (x) + (unsigned int)(ac); 
    (a) = ROTATE_LEFT ((a), (s)); 
    (a) += (b); 
}
/* MD5 initialization. Begins an MD5 operation, writing a new context. */
static void MD5Init (MD5_CTX *context)
{
    context->count[0] = context->count[1] = 0;
    /* Load magic initialization constants.  */
    context->state[0] = 0x67452301;
    context->state[1] = 0xefcdab89;
    context->state[2] = 0x98badcfe;
    context->state[3] = 0x10325476;
}
/*
* MD5 block update operation. Continues an MD5 message-digest
* operation, processing another message block, and updating the
* context.
*/
static void MD5Update ( MD5_CTX *context, unsigned char *input, unsigned int inputLen)
{
    unsigned int i, index, partLen;
    /* Compute number of bytes mod 64 */
    index = (unsigned int)((context->count[0] >> 3) & 0x3F);
    /* Update number of bits */
    if ((context->count[0] += ((unsigned int)inputLen << 3))
        < ((unsigned int)inputLen << 3))
        context->count[1]++;
    context->count[1] += ((unsigned int)inputLen >> 29);
    partLen = 64 -index;
    /* Transform as many times as possible. */
    if (inputLen >= partLen) {
        memcpy((void *)&context->buffer[index], (const void *)input,
            partLen);
        __md5_Transform (context->state, (unsigned char*)context->buffer);
        for (i = partLen; i + 63 < inputLen; i += 64)
            __md5_Transform (context->state, &input[i]);
        index = 0;
    }
    else
        i = 0;
    /* Buffer remaining input */
    memcpy ((void *)&context->buffer[index], (const void *)&input[i],
        inputLen-i);
}
/*
* MD5 padding. Adds padding followed by original length.
*/
static void __md5_Pad ( MD5_CTX *context)
{
    unsigned char bits[8];
    unsigned int index, padLen;
    unsigned char PADDING[64];
    memset(PADDING, 0, sizeof(PADDING));
    PADDING[0] = 0x80;
    /* Save number of bits */
    __md5_Encode (bits, context->count, 8);
    /* Pad out to 56 mod 64. */
    index = (unsigned int)((context->count[0] >> 3) & 0x3f);
    padLen = (index < 56) ? (56 - index) : (120 - index);
    MD5Update (context, PADDING, padLen);
    /* Append length (before padding) */
    MD5Update (context, bits, 8);
}
/*
* MD5 finalization. Ends an MD5 message-digest operation, writing the
* the message digest and zeroizing the context.
*/
static void MD5Final ( unsigned char digest[16], MD5_CTX *context)
{
    /* Do padding. */
    __md5_Pad (context);
    /* Store state in digest */
    __md5_Encode (digest, context->state, 16);
    /* Zeroize sensitive information. */
    memset ((void *)context, 0, sizeof (*context));
}
/* MD5 basic transformation. Transforms state based on block. */
static void
__md5_Transform (unsigned int state[4], unsigned char block[64])
{
    unsigned int a, b, c, d, x[16];
    a=state[0];
    b=state[1];
    c=state[2];
    d=state[3];
    __md5_Decode (x, block, 64);
    /* Round 1 */
#define S11 7
#define S12 12
#define S13 17
#define S14 22
    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 */
#define S21 5
#define S22 9
#define S23 14
#define S24 20
    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 */
#define S31 4
#define S32 11
#define S33 16
#define S34 23
    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 */
#define S41 6
#define S42 10
#define S43 15
#define S44 21
    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;
    /* Zeroize sensitive information. */
    memset ((void *)x, 0, sizeof (x));
}
void EncryptMD5(unsigned char *output, unsigned char *input)
{
    MD5_CTX context;
    MD5Init(&context);
    MD5Update(&context, input, (unsigned int)strlen((char *)input));
    MD5Final(output, &context);
    return;
}
void EncryptMD5str(char *output, unsigned char *input, int len)
{
    unsigned char strcrypt[16];
    int i;
    MD5_CTX context;
    MD5Init(&context);
    MD5Update(&context, input, len);
    MD5Final(strcrypt, &context);
    for (i=0; i < 16; i++)
        sprintf(&output[i*2], "%02x", strcrypt[i]);
    return;
}

测试用例

int main(int argc, char **argv)
{
    int content_source_len = 0;
    char* source_content = NULL;
    FILE* fp = fopen(m_contentSource.c_str() , "rb");
    if (fp != NULL)
    {
        fseek(fp, 0, SEEK_END);
        content_source_len = ftell(fp);
        fseek(fp, 0, SEEK_SET);
        source_content =  (char*) malloc(content_source_len * sizeof(char));
        fread(source_content, content_source_len , sizeof(char), fp);
        fclose(fp);
    }
       //md5code_string是要发送的校验码
    char md5code_string[50] = {0};
    EncryptMD5str(md5code_string, (unsigned char *)source_content, content_source_len);
}