C实现MD5

拼搏现实的明天。 2022-08-18 02:06 131阅读 0赞

### MD5.h ###

#ifndef MD5_H  
    #define MD5_H
    
    typedef struct
    {
        unsigned int count[2];
        unsigned int state[4];
        unsigned char buffer[64];
    }MD5_CTX;
    
    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);
    
    void byte2str(unsigned char* byte, int byte_len, char* str);
    
    #endif

### MD5.c ###

#include <memory.h>  
    #include "md5.h"
    
    #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; \
    		  }
    
    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;
    }
    
    void byte2str(unsigned char* byte, int byte_len, char* str)
    {
    	const char szTable[] = "0123456789abcdef";
    	int i = 0;
    	for (i = 0; i < byte_len; i++)
    	{
    		*str++ = szTable[byte[i] >> 4];
    		*str++ = szTable[byte[i] & 0x0f];
    	}
    	*str = '\0';
    }

main.c

#include <stdio.h>
    #include "md5.h"
    
    int main()
    {
    	char* adm = "admin";
    	MD5_CTX md5;
    	MD5Init(&md5);
    	unsigned char decrypt[16] = { 0 };
    	MD5Update(&md5, adm, strlen(adm));
    	MD5Final(&md5, decrypt);
    	char pout[64] = { 0 };
    	byte2str(decrypt, 16, pout);
    	printf("md5:%s\n", pout);//输出即为md5值,长度32
    }