C实现MD5

MD5.h

#ifndef MD5_H  #define MD5_Htypedef 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}