网上有 md5.c , md5.h, 但是里面只有 MD5Init(), MD5Update(), MD5Final() 三个函数,
只可以直接对字符进行操作, 而没有直接求文件md5的接口. 以下是我的实现, 可计算32位和16位的md5值.
复制代码 代码如下:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "md5.h"
char *MD5_file (char *path, int md5_len)
{
FILE *fp = fopen (path, "rb");
MD5_CTX mdContext;
int bytes;
unsigned char data[1024];
char *file_md5;
int i;
if (fp == NULL) {
fprintf (stderr, "fopen %s failed\n", path);
return NULL;
}
MD5Init (&mdContext);
while ((bytes = fread (data, 1, 1024, fp)) != 0)
{
MD5Update (&mdContext, data, bytes);
}
MD5Final (&mdContext);

file_md5 = (char *)malloc((md5_len + 1) * sizeof(char));
if(file_md5 == NULL)
{
fprintf(stderr, "malloc failed.\n");
return NULL;
}
memset(file_md5, 0, (md5_len + 1));

if(md5_len == 16)
{
for(i=4; i<12; i++)
{
sprintf(&file_md5[(i-4)*2], "%02x", mdContext.digest[i]);
}
}
else if(md5_len == 32)
{
for(i=0; i<16; i++)
{
sprintf(&file_md5[i*2], "%02x", mdContext.digest[i]);
}
}
else
{
fclose(fp);
free(file_md5);
return NULL;
}

fclose (fp);
return file_md5;
}
int main(int argc, char *argv[])
{
char *md5;

md5 = MD5_file("temp", 16);
printf("16: %s\n", md5);
free(md5);

md5 = MD5_file("temp", 32);
printf("32: %s\n", md5);
free(md5);
return 0;
}

以下是 md5.c的源码
复制代码 代码如下:
#include "md5.h"
/*
**********************************************************************
** md5.c **
** RSA Data Security, Inc. MD5 Message Digest Algorithm **
** Created: 2/17/90 RLR **
** Revised: 1/91 SRD,AJ,BSK,JT Reference C Version **
**********************************************************************
*/
/*
**********************************************************************
** Copyright (C) 1990, RSA Data Security, Inc. All rights reserved. **
** **
** License to copy and use this software is granted provided that **
** it is identified as the "RSA Data Security, Inc. MD5 Message **
** Digest Algorithm" in all material mentioning or referencing this **
** software or this function. **
** **
** License is also granted to make and use derivative works **
** provided that such works are identified as "derived from the RSA **
** Data Security, Inc. MD5 Message Digest Algorithm" in all **
** material mentioning or referencing the derived work. **
** **
** RSA Data Security, Inc. makes no representations concerning **
** either the merchantability of this software or the suitability **
** of this software for any particular purpose. It is provided "as **
** is" without express or implied warranty of any kind. **
** **
** These notices must be retained in any copies of any part of this **
** documentation and/or software. **
**********************************************************************
*/



static void Transform ();
static unsigned char PADDING[64] = {
0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};

#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 ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))


#define FF(a, b, c, d, x, s, ac) \
{(a) += F ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
}
#define GG(a, b, c, d, x, s, ac) \
{(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
}
#define HH(a, b, c, d, x, s, ac) \
{(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
}
#define II(a, b, c, d, x, s, ac) \
{(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac); \
(a) = ROTATE_LEFT ((a), (s)); \
(a) += (b); \
}
void MD5Init (MD5_CTX *mdContext)
{
mdContext->i[0] = mdContext->i[1] = (UINT4)0;

mdContext->buf[0] = (UINT4)0x67452301;
mdContext->buf[1] = (UINT4)0xefcdab89;
mdContext->buf[2] = (UINT4)0x98badcfe;
mdContext->buf[3] = (UINT4)0x10325476;
}
void MD5Update (MD5_CTX *mdContext, unsigned char *inBuf, unsigned int inLen)
{
UINT4 in[16];
int mdi;
unsigned int i, ii;

mdi = (int)((mdContext->i[0] >> 3) & 0x3F);

if ((mdContext->i[0] + ((UINT4)inLen << 3)) < mdContext->i[0])
mdContext->i[1]++;
mdContext->i[0] += ((UINT4)inLen << 3);
mdContext->i[1] += ((UINT4)inLen >> 29);
while (inLen--) {

mdContext->in[mdi++] = *inBuf++;

if (mdi == 0x40) {
for (i = 0, ii = 0; i < 16; i++, ii += 4)
in[i] = (((UINT4)mdContext->in[ii+3]) << 24) |
(((UINT4)mdContext->in[ii+2]) << 16) |
(((UINT4)mdContext->in[ii+1]) << 8) |
((UINT4)mdContext->in[ii]);
Transform (mdContext->buf, in);
mdi = 0;
}
}
}
void MD5Final (MD5_CTX *mdContext)
{
UINT4 in[16];
int mdi;
unsigned int i, ii;
unsigned int padLen;

in[14] = mdContext->i[0];
in[15] = mdContext->i[1];

mdi = (int)((mdContext->i[0] >> 3) & 0x3F);

padLen = (mdi < 56) ? (56 - mdi) : (120 - mdi);
MD5Update (mdContext, PADDING, padLen);

for (i = 0, ii = 0; i < 14; i++, ii += 4)
in[i] = (((UINT4)mdContext->in[ii+3]) << 24) |
(((UINT4)mdContext->in[ii+2]) << 16) |
(((UINT4)mdContext->in[ii+1]) << 8) |
((UINT4)mdContext->in[ii]);
Transform (mdContext->buf, in);

for (i = 0, ii = 0; i < 4; i++, ii += 4) {
mdContext->digest[ii] = (unsigned char)(mdContext->buf[i] & 0xFF);
mdContext->digest[ii+1] =
(unsigned char)((mdContext->buf[i] >> 8) & 0xFF);
mdContext->digest[ii+2] =
(unsigned char)((mdContext->buf[i] >> 16) & 0xFF);
mdContext->digest[ii+3] =
(unsigned char)((mdContext->buf[i] >> 24) & 0xFF);
}
}

static void Transform (UINT4 *buf, UINT4 *in)
{
UINT4 a = buf[0], b = buf[1], c = buf[2], d = buf[3];

#define S11 7
#define S12 12
#define S13 17
#define S14 22
FF ( a, b, c, d, in[ 0], S11, 3614090360);
FF ( d, a, b, c, in[ 1], S12, 3905402710);
FF ( c, d, a, b, in[ 2], S13, 606105819);
FF ( b, c, d, a, in[ 3], S14, 3250441966);
FF ( a, b, c, d, in[ 4], S11, 4118548399);
FF ( d, a, b, c, in[ 5], S12, 1200080426);
FF ( c, d, a, b, in[ 6], S13, 2821735955);
FF ( b, c, d, a, in[ 7], S14, 4249261313);
FF ( a, b, c, d, in[ 8], S11, 1770035416);
FF ( d, a, b, c, in[ 9], S12, 2336552879);
FF ( c, d, a, b, in[10], S13, 4294925233);
FF ( b, c, d, a, in[11], S14, 2304563134);
FF ( a, b, c, d, in[12], S11, 1804603682);
FF ( d, a, b, c, in[13], S12, 4254626195);
FF ( c, d, a, b, in[14], S13, 2792965006);
FF ( b, c, d, a, in[15], S14, 1236535329);

#define S21 5
#define S22 9
#define S23 14
#define S24 20
GG ( a, b, c, d, in[ 1], S21, 4129170786);
GG ( d, a, b, c, in[ 6], S22, 3225465664);
GG ( c, d, a, b, in[11], S23, 643717713);
GG ( b, c, d, a, in[ 0], S24, 3921069994);
GG ( a, b, c, d, in[ 5], S21, 3593408605);
GG ( d, a, b, c, in[10], S22, 38016083);
GG ( c, d, a, b, in[15], S23, 3634488961);
GG ( b, c, d, a, in[ 4], S24, 3889429448);
GG ( a, b, c, d, in[ 9], S21, 568446438);
GG ( d, a, b, c, in[14], S22, 3275163606);
GG ( c, d, a, b, in[ 3], S23, 4107603335);
GG ( b, c, d, a, in[ 8], S24, 1163531501);
GG ( a, b, c, d, in[13], S21, 2850285829);
GG ( d, a, b, c, in[ 2], S22, 4243563512);
GG ( c, d, a, b, in[ 7], S23, 1735328473);
GG ( b, c, d, a, in[12], S24, 2368359562);

#define S31 4
#define S32 11
#define S33 16
#define S34 23
HH ( a, b, c, d, in[ 5], S31, 4294588738);
HH ( d, a, b, c, in[ 8], S32, 2272392833);
HH ( c, d, a, b, in[11], S33, 1839030562);
HH ( b, c, d, a, in[14], S34, 4259657740);
HH ( a, b, c, d, in[ 1], S31, 2763975236);
HH ( d, a, b, c, in[ 4], S32, 1272893353);
HH ( c, d, a, b, in[ 7], S33, 4139469664);
HH ( b, c, d, a, in[10], S34, 3200236656);
HH ( a, b, c, d, in[13], S31, 681279174);
HH ( d, a, b, c, in[ 0], S32, 3936430074);
HH ( c, d, a, b, in[ 3], S33, 3572445317);
HH ( b, c, d, a, in[ 6], S34, 76029189);
HH ( a, b, c, d, in[ 9], S31, 3654602809);
HH ( d, a, b, c, in[12], S32, 3873151461);
HH ( c, d, a, b, in[15], S33, 530742520);
HH ( b, c, d, a, in[ 2], S34, 3299628645);

#define S41 6
#define S42 10
#define S43 15
#define S44 21
II ( a, b, c, d, in[ 0], S41, 4096336452);
II ( d, a, b, c, in[ 7], S42, 1126891415);
II ( c, d, a, b, in[14], S43, 2878612391);
II ( b, c, d, a, in[ 5], S44, 4237533241);
II ( a, b, c, d, in[12], S41, 1700485571);
II ( d, a, b, c, in[ 3], S42, 2399980690);
II ( c, d, a, b, in[10], S43, 4293915773);
II ( b, c, d, a, in[ 1], S44, 2240044497);
II ( a, b, c, d, in[ 8], S41, 1873313359);
II ( d, a, b, c, in[15], S42, 4264355552);
II ( c, d, a, b, in[ 6], S43, 2734768916);
II ( b, c, d, a, in[13], S44, 1309151649);
II ( a, b, c, d, in[ 4], S41, 4149444226);
II ( d, a, b, c, in[11], S42, 3174756917);
II ( c, d, a, b, in[ 2], S43, 718787259);
II ( b, c, d, a, in[ 9], S44, 3951481745);
buf[0] += a;
buf[1] += b;
buf[2] += c;
buf[3] += d;
}
/*
**********************************************************************
** End of md5.c **
******************************* (cut) ********************************
*/

以下是 md5.h 的源码
复制代码 代码如下:
/*
**********************************************************************
** md5.h -- Header file for implementation of MD5 **
** RSA Data Security, Inc. MD5 Message Digest Algorithm **
** Created: 2/17/90 RLR **
** Revised: 12/27/90 SRD,AJ,BSK,JT Reference C version **
** Revised (for MD5): RLR 4/27/91 **
** -- G modified to have y&~z instead of y&z **
** -- FF, GG, HH modified to add in last register done **
** -- Access pattern: round 2 works mod 5, round 3 works mod 3 **
** -- distinct additive constant for each step **
** -- round 4 added, working mod 7 **
**********************************************************************
*/
/*
**********************************************************************
** Copyright (C) 1990, RSA Data Security, Inc. All rights reserved. **
** **
** License to copy and use this software is granted provided that **
** it is identified as the "RSA Data Security, Inc. MD5 Message **
** Digest Algorithm" in all material mentioning or referencing this **
** software or this function. **
** **
** License is also granted to make and use derivative works **
** provided that such works are identified as "derived from the RSA **
** Data Security, Inc. MD5 Message Digest Algorithm" in all **
** material mentioning or referencing the derived work. **
** **
** RSA Data Security, Inc. makes no representations concerning **
** either the merchantability of this software or the suitability **
** of this software for any particular purpose. It is provided "as **
** is" without express or implied warranty of any kind. **
** **
** These notices must be retained in any copies of any part of this **
** documentation and/or software. **
**********************************************************************
*/

typedef unsigned long int UINT4;

typedef struct {
UINT4 i[2];
UINT4 buf[4];
unsigned char in[64];
unsigned char digest[16];
} MD5_CTX;
void MD5Init ();
void MD5Update ();
void MD5Final ();
/*
**********************************************************************
** End of md5.h **
******************************* (cut) ********************************
*/