c 擷取檔案 MD5 值

網上有 md5.c , md5.h, 但是裡面只有 MD5Init(), MD5Update(), MD5Final() 三個函數, 

只可以直接對字元進行操作, 而沒有直接求檔案md5的介面. 以下是我的實現, 可計算32位和16位的md5值.

/***************************************************************************** *  Copyright          :  All Rights Reserved. * *  Date               :  2012-09-15 22:37:49 *  Author/Corporation :  Dengzhaoqun *  Email              :  dengzhaoqun@163.com *****************************************************************************/#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的源碼

#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.                                   ** ********************************************************************** *//* -- include the following line if the md5.h header file is separate -- *//* #include "md5.h" *//* forward declaration */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};/* F, G and H are basic MD5 functions: selection, majority, parity */#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) + (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;  /* Load magic initialization constants.   */  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;  /* compute number of bytes mod 64 */  mdi = (int)((mdContext->i[0] >> 3) & 0x3F);  /* update number of bits */  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--) {    /* add new character to buffer, increment mdi */    mdContext->in[mdi++] = *inBuf++;    /* transform if necessary */    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;  /* save number of bits */  in[14] = mdContext->i[0];  in[15] = mdContext->i[1];  /* compute number of bytes mod 64 */  mdi = (int)((mdContext->i[0] >> 3) & 0x3F);  /* pad out to 56 mod 64 */  padLen = (mdi < 56) ? (56 - mdi) : (120 - mdi);  MD5Update (mdContext, PADDING, padLen);  /* append length in bits and transform */  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);  /* store buffer in digest */  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);  }}/* Basic MD5 step. Transform buf based on in. */static void Transform (UINT4 *buf, UINT4 *in){  UINT4 a = buf[0], b = buf[1], c = buf[2], d = buf[3];  /* Round 1 */#define S11 7#define S12 12#define S13 17#define S14 22  FF ( a, b, c, d, in[ 0], S11, 3614090360); /* 1 */  FF ( d, a, b, c, in[ 1], S12, 3905402710); /* 2 */  FF ( c, d, a, b, in[ 2], S13,  606105819); /* 3 */  FF ( b, c, d, a, in[ 3], S14, 3250441966); /* 4 */  FF ( a, b, c, d, in[ 4], S11, 4118548399); /* 5 */  FF ( d, a, b, c, in[ 5], S12, 1200080426); /* 6 */  FF ( c, d, a, b, in[ 6], S13, 2821735955); /* 7 */  FF ( b, c, d, a, in[ 7], S14, 4249261313); /* 8 */  FF ( a, b, c, d, in[ 8], S11, 1770035416); /* 9 */  FF ( d, a, b, c, in[ 9], S12, 2336552879); /* 10 */  FF ( c, d, a, b, in[10], S13, 4294925233); /* 11 */  FF ( b, c, d, a, in[11], S14, 2304563134); /* 12 */  FF ( a, b, c, d, in[12], S11, 1804603682); /* 13 */  FF ( d, a, b, c, in[13], S12, 4254626195); /* 14 */  FF ( c, d, a, b, in[14], S13, 2792965006); /* 15 */  FF ( b, c, d, a, in[15], S14, 1236535329); /* 16 */  /* Round 2 */#define S21 5#define S22 9#define S23 14#define S24 20  GG ( a, b, c, d, in[ 1], S21, 4129170786); /* 17 */  GG ( d, a, b, c, in[ 6], S22, 3225465664); /* 18 */  GG ( c, d, a, b, in[11], S23,  643717713); /* 19 */  GG ( b, c, d, a, in[ 0], S24, 3921069994); /* 20 */  GG ( a, b, c, d, in[ 5], S21, 3593408605); /* 21 */  GG ( d, a, b, c, in[10], S22,   38016083); /* 22 */  GG ( c, d, a, b, in[15], S23, 3634488961); /* 23 */  GG ( b, c, d, a, in[ 4], S24, 3889429448); /* 24 */  GG ( a, b, c, d, in[ 9], S21,  568446438); /* 25 */  GG ( d, a, b, c, in[14], S22, 3275163606); /* 26 */  GG ( c, d, a, b, in[ 3], S23, 4107603335); /* 27 */  GG ( b, c, d, a, in[ 8], S24, 1163531501); /* 28 */  GG ( a, b, c, d, in[13], S21, 2850285829); /* 29 */  GG ( d, a, b, c, in[ 2], S22, 4243563512); /* 30 */  GG ( c, d, a, b, in[ 7], S23, 1735328473); /* 31 */  GG ( b, c, d, a, in[12], S24, 2368359562); /* 32 */  /* Round 3 */#define S31 4#define S32 11#define S33 16#define S34 23  HH ( a, b, c, d, in[ 5], S31, 4294588738); /* 33 */  HH ( d, a, b, c, in[ 8], S32, 2272392833); /* 34 */  HH ( c, d, a, b, in[11], S33, 1839030562); /* 35 */  HH ( b, c, d, a, in[14], S34, 4259657740); /* 36 */  HH ( a, b, c, d, in[ 1], S31, 2763975236); /* 37 */  HH ( d, a, b, c, in[ 4], S32, 1272893353); /* 38 */  HH ( c, d, a, b, in[ 7], S33, 4139469664); /* 39 */  HH ( b, c, d, a, in[10], S34, 3200236656); /* 40 */  HH ( a, b, c, d, in[13], S31,  681279174); /* 41 */  HH ( d, a, b, c, in[ 0], S32, 3936430074); /* 42 */  HH ( c, d, a, b, in[ 3], S33, 3572445317); /* 43 */  HH ( b, c, d, a, in[ 6], S34,   76029189); /* 44 */  HH ( a, b, c, d, in[ 9], S31, 3654602809); /* 45 */  HH ( d, a, b, c, in[12], S32, 3873151461); /* 46 */  HH ( c, d, a, b, in[15], S33,  530742520); /* 47 */  HH ( b, c, d, a, in[ 2], S34, 3299628645); /* 48 */  /* Round 4 */#define S41 6#define S42 10#define S43 15#define S44 21  II ( a, b, c, d, in[ 0], S41, 4096336452); /* 49 */  II ( d, a, b, c, in[ 7], S42, 1126891415); /* 50 */  II ( c, d, a, b, in[14], S43, 2878612391); /* 51 */  II ( b, c, d, a, in[ 5], S44, 4237533241); /* 52 */  II ( a, b, c, d, in[12], S41, 1700485571); /* 53 */  II ( d, a, b, c, in[ 3], S42, 2399980690); /* 54 */  II ( c, d, a, b, in[10], S43, 4293915773); /* 55 */  II ( b, c, d, a, in[ 1], S44, 2240044497); /* 56 */  II ( a, b, c, d, in[ 8], S41, 1873313359); /* 57 */  II ( d, a, b, c, in[15], S42, 4264355552); /* 58 */  II ( c, d, a, b, in[ 6], S43, 2734768916); /* 59 */  II ( b, c, d, a, in[13], S44, 1309151649); /* 60 */  II ( a, b, c, d, in[ 4], S41, 4149444226); /* 61 */  II ( d, a, b, c, in[11], S42, 3174756917); /* 62 */  II ( c, d, a, b, in[ 2], S43,  718787259); /* 63 */  II ( b, c, d, a, in[ 9], S44, 3951481745); /* 64 */  buf[0] += a;  buf[1] += b;  buf[2] += c;  buf[3] += d;}/* ********************************************************************** ** End of md5.c                                                     ** ******************************* (cut) ******************************** */

以下是 md5.h 的源碼

/* ********************************************************************** ** 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 a 32 bit type */typedef unsigned long int UINT4;/* Data structure for MD5 (Message Digest) computation */typedef struct {  UINT4 i[2];                   /* number of _bits_ handled mod 2^64 */  UINT4 buf[4];                                    /* scratch buffer */  unsigned char in[64];                              /* input buffer */  unsigned char digest[16];     /* actual digest after MD5Final call */} MD5_CTX;void MD5Init ();void MD5Update ();void MD5Final ();/* ********************************************************************** ** End of md5.h                                                     ** ******************************* (cut) ******************************** */