md5函數C語言實現

轉自http://witmax.cn/c-md5-code.html，作者也是網上轉載的，但沒標明出處。

網上找到的md5函數的代碼，試了一下，可以用，記錄一下。包括三個檔案，依次如下：

標頭檔md5.h

#ifndef MD5_H#define MD5_Htypedef 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語言檔案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函數測試代碼檔案

#include <stdio.h>#include <stdlib.h>#include <string.h>#include "md5.h"int main(int argc, char *argv[]){MD5_CTX md5;MD5Init(&md5);         int i;unsigned char encrypt[] ="admin";//21232f297a57a5a743894a0e4a801fc3unsigned char decrypt[16];    MD5Update(&md5,encrypt,strlen((char *)encrypt));MD5Final(&md5,decrypt);        printf("加密前:%s\n加密後:",encrypt);for(i=0;i<16;i++){printf("%02x",decrypt[i]);}getchar();return 0;}

MD5加密常用字元

7a57a5a743894a0e admin(16位MD5小寫加密)
972130B75066C825 ADMIN(16位MD5大寫加密)
21232f297a57a5a743894a0e4a801fc3 admin(32位MD5小寫加密)
73ACD9A5972130B75066C82595A1FAE3 ADMIN(32位MD5大寫加密)
49ba59abbe56e057 123456(16位MD5小寫加密)
e10adc3949ba59abbe56e057f20f883e 123456(32位MD5小寫加密)
469e80d32c0559f8 admin888(16位MD5小寫加密)
2299413865C28A35 ADMIN888(16位MD5大寫加密)
7fef6171469e80d32c0559f88b377245 admin888(32位MD5小寫加密)
A1F63A962299413865C28A3593D359B0 ADMIN888(32位MD5大寫加密) 

PS.md5知識掃盲

MD5：是一個具體的演算法,散列演算法，哈西演算法，但非密碼編譯演算法（因為沒有密鑰），可用於加密（無法復原）
MD5是一種單向散列函數，單向散列函數的作用是將任何長度的一段資料散列成固定長度。常用於產生訊息認證碼等等，可以與非對稱演算法一起用於數位簽章。
標準見http://www.ietf.org/rfc/rfc1321.txt
MD5好象被國內的一個教授破解了,順便給大家一個地址http://www.cmd5.com/,有時候應該會很方便的.:)