【C】md5函数实现代码

    网上找到的md5函数的代码,试了一下,可以用,记录一下。包括三个文件,依次如下:

    头文件md5.h

    
    #ifndef MD5_H
    #define MD5_H
    
    typedef struct
    {
        unsigned int count[2];
        unsigned int state[4];
        unsigned char buffer[64];   
    }MD5_CTX;
    
                            
    #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 + 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; \
              }                                            
    void MD5Init(MD5_CTX *context);
    void MD5Update(MD5_CTX *context,unsigned char *input,unsigned int inputlen);
    void MD5Final(MD5_CTX *context,unsigned char digest[16]);
    void MD5Transform(unsigned int state[4],unsigned char block[64]);
    void MD5Encode(unsigned char *output,unsigned int *input,unsigned int len);
    void MD5Decode(unsigned int *output,unsigned char *input,unsigned int len);
    
    #endif



    C语言文件md5.c

    
    #include <memory.h>
    #include "md5.h"
    
    unsigned char PADDING[]={0x80,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
                             0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
                             0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
                             0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
                            
    void MD5Init(MD5_CTX *context)
    {
         context->count[0] = 0;
         context->count[1] = 0;
         context->state[0] = 0x67452301;
         context->state[1] = 0xEFCDAB89;
         context->state[2] = 0x98BADCFE;
         context->state[3] = 0x10325476;
    }
    void MD5Update(MD5_CTX *context,unsigned char *input,unsigned int inputlen)
    {
        unsigned int i = 0,index = 0,partlen = 0;
        index = (context->count[0] >> 3) & 0x3F;
        partlen = 64 - index;
        context->count[0] += inputlen << 3;
        if(context->count[0] < (inputlen << 3))
           context->count[1]++;
        context->count[1] += inputlen >> 29;
       
        if(inputlen >= partlen)
        {
           memcpy(&context->buffer[index],input,partlen);
           MD5Transform(context->state,context->buffer);
           for(i = partlen;i+64 <= inputlen;i+=64)
               MD5Transform(context->state,&input[i]);
           index = 0;        
        }  
        else
        {
            i = 0;
        }
        memcpy(&context->buffer[index],&input[i],inputlen-i);
    }
    void MD5Final(MD5_CTX *context,unsigned char digest[16])
    {
        unsigned int index = 0,padlen = 0;
        unsigned char bits[8];
        index = (context->count[0] >> 3) & 0x3F;
        padlen = (index < 56)?(56-index):(120-index);
        MD5Encode(bits,context->count,8);
        MD5Update(context,PADDING,padlen);
        MD5Update(context,bits,8);
        MD5Encode(digest,context->state,16);
    }
    void MD5Encode(unsigned char *output,unsigned int *input,unsigned int len)
    {
        unsigned int i = 0,j = 0;
        while(j < len)
        {
             output[j] = input[i] & 0xFF;  
             output[j+1] = (input[i] >> 8) & 0xFF;
             output[j+2] = (input[i] >> 16) & 0xFF;
             output[j+3] = (input[i] >> 24) & 0xFF;
             i++;
             j+=4;
        }
    }
    void MD5Decode(unsigned int *output,unsigned char *input,unsigned int len)
    {
         unsigned int i = 0,j = 0;
         while(j < len)
         {
               output[i] = (input[j]) |
                           (input[j+1] << 8) |
                           (input[j+2] << 16) |
                           (input[j+3] << 24);
               i++;
               j+=4; 
         }
    }
    void MD5Transform(unsigned int state[4],unsigned char block[64])
    {
         unsigned int a = state[0];
         unsigned int b = state[1];
         unsigned int c = state[2];
         unsigned int d = state[3];
         unsigned int x[64];
         MD5Decode(x,block,64);
         FF(a, b, c, d, x[ 0], 7, 0xd76aa478); /* 1 */
     FF(d, a, b, c, x[ 1], 12, 0xe8c7b756); /* 2 */
     FF(c, d, a, b, x[ 2], 17, 0x242070db); /* 3 */
     FF(b, c, d, a, x[ 3], 22, 0xc1bdceee); /* 4 */
     FF(a, b, c, d, x[ 4], 7, 0xf57c0faf); /* 5 */
     FF(d, a, b, c, x[ 5], 12, 0x4787c62a); /* 6 */
     FF(c, d, a, b, x[ 6], 17, 0xa8304613); /* 7 */
     FF(b, c, d, a, x[ 7], 22, 0xfd469501); /* 8 */
     FF(a, b, c, d, x[ 8], 7, 0x698098d8); /* 9 */
     FF(d, a, b, c, x[ 9], 12, 0x8b44f7af); /* 10 */
     FF(c, d, a, b, x[10], 17, 0xffff5bb1); /* 11 */
     FF(b, c, d, a, x[11], 22, 0x895cd7be); /* 12 */
     FF(a, b, c, d, x[12], 7, 0x6b901122); /* 13 */
     FF(d, a, b, c, x[13], 12, 0xfd987193); /* 14 */
     FF(c, d, a, b, x[14], 17, 0xa679438e); /* 15 */
     FF(b, c, d, a, x[15], 22, 0x49b40821); /* 16 */
    
     /* Round 2 */
     GG(a, b, c, d, x[ 1], 5, 0xf61e2562); /* 17 */
     GG(d, a, b, c, x[ 6], 9, 0xc040b340); /* 18 */
     GG(c, d, a, b, x[11], 14, 0x265e5a51); /* 19 */
     GG(b, c, d, a, x[ 0], 20, 0xe9b6c7aa); /* 20 */
     GG(a, b, c, d, x[ 5], 5, 0xd62f105d); /* 21 */
     GG(d, a, b, c, x[10], 9,  0x2441453); /* 22 */
     GG(c, d, a, b, x[15], 14, 0xd8a1e681); /* 23 */
     GG(b, c, d, a, x[ 4], 20, 0xe7d3fbc8); /* 24 */
     GG(a, b, c, d, x[ 9], 5, 0x21e1cde6); /* 25 */
     GG(d, a, b, c, x[14], 9, 0xc33707d6); /* 26 */
     GG(c, d, a, b, x[ 3], 14, 0xf4d50d87); /* 27 */
     GG(b, c, d, a, x[ 8], 20, 0x455a14ed); /* 28 */
     GG(a, b, c, d, x[13], 5, 0xa9e3e905); /* 29 */
     GG(d, a, b, c, x[ 2], 9, 0xfcefa3f8); /* 30 */
     GG(c, d, a, b, x[ 7], 14, 0x676f02d9); /* 31 */
     GG(b, c, d, a, x[12], 20, 0x8d2a4c8a); /* 32 */
    
     /* Round 3 */
     HH(a, b, c, d, x[ 5], 4, 0xfffa3942); /* 33 */
     HH(d, a, b, c, x[ 8], 11, 0x8771f681); /* 34 */
     HH(c, d, a, b, x[11], 16, 0x6d9d6122); /* 35 */
     HH(b, c, d, a, x[14], 23, 0xfde5380c); /* 36 */
     HH(a, b, c, d, x[ 1], 4, 0xa4beea44); /* 37 */
     HH(d, a, b, c, x[ 4], 11, 0x4bdecfa9); /* 38 */
     HH(c, d, a, b, x[ 7], 16, 0xf6bb4b60); /* 39 */
     HH(b, c, d, a, x[10], 23, 0xbebfbc70); /* 40 */
     HH(a, b, c, d, x[13], 4, 0x289b7ec6); /* 41 */
     HH(d, a, b, c, x[ 0], 11, 0xeaa127fa); /* 42 */
     HH(c, d, a, b, x[ 3], 16, 0xd4ef3085); /* 43 */
     HH(b, c, d, a, x[ 6], 23,  0x4881d05); /* 44 */
     HH(a, b, c, d, x[ 9], 4, 0xd9d4d039); /* 45 */
     HH(d, a, b, c, x[12], 11, 0xe6db99e5); /* 46 */
     HH(c, d, a, b, x[15], 16, 0x1fa27cf8); /* 47 */
     HH(b, c, d, a, x[ 2], 23, 0xc4ac5665); /* 48 */
    
     /* Round 4 */
     II(a, b, c, d, x[ 0], 6, 0xf4292244); /* 49 */
     II(d, a, b, c, x[ 7], 10, 0x432aff97); /* 50 */
     II(c, d, a, b, x[14], 15, 0xab9423a7); /* 51 */
     II(b, c, d, a, x[ 5], 21, 0xfc93a039); /* 52 */
     II(a, b, c, d, x[12], 6, 0x655b59c3); /* 53 */
     II(d, a, b, c, x[ 3], 10, 0x8f0ccc92); /* 54 */
     II(c, d, a, b, x[10], 15, 0xffeff47d); /* 55 */
     II(b, c, d, a, x[ 1], 21, 0x85845dd1); /* 56 */
     II(a, b, c, d, x[ 8], 6, 0x6fa87e4f); /* 57 */
     II(d, a, b, c, x[15], 10, 0xfe2ce6e0); /* 58 */
     II(c, d, a, b, x[ 6], 15, 0xa3014314); /* 59 */
     II(b, c, d, a, x[13], 21, 0x4e0811a1); /* 60 */
     II(a, b, c, d, x[ 4], 6, 0xf7537e82); /* 61 */
     II(d, a, b, c, x[11], 10, 0xbd3af235); /* 62 */
     II(c, d, a, b, x[ 2], 15, 0x2ad7d2bb); /* 63 */
     II(b, c, d, a, x[ 9], 21, 0xeb86d391); /* 64 */
         state[0] += a;
         state[1] += b;
         state[2] += c;
         state[3] += d;
    }
    
    

    md5函数测试代码文件

    
    #include <stdio.h>
    #include <stdlib.h>
    #include "md5.h"
    
    int main(int argc, char *argv[])
    {
     MD5_CTX md5;
     MD5Init(&md5);         
     int i;
     unsigned char encrypt[] ="admin";//21232f297a57a5a743894a0e4a801fc3
     unsigned char decrypt[16];    
     MD5Update(&md5,encrypt,strlen((char *)encrypt));
     MD5Final(&md5,decrypt);        
     printf("加密前:%s\n加密后:",encrypt);
     for(i=0;i<16;i++)
     {
      printf("%02x",decrypt[i]);
     }
    
     getchar();
    
     return 0;
    }


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