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用c 获取文件MD5值的实现方法

  • 时间:2020-08-04 03:17 编辑: 来源: 阅读:
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摘要:用c 获取文件MD5值的实现方法
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.
[u]复制代码[/u] 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], "x", mdContext.digest[i]);   }  }  else if(md5_len == 32)  {   for(i=0; i<16; i++)   {    sprintf(&file_md5[i*2], "x", 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
[u]复制代码[/u] 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.                                   **  **********************************************************************  */ /* -- 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 的源码
[u]复制代码[/u] 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 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) ********************************  */
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