C语言实现md5函数代码

网上找到的实现md5函数代码，包括一个头文件md5.h和一个源文件md5.c，用下面的测试代码test.c测试通过，各文件依次如下：

头文件md5.h

[cpp] view plaincopy

#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

源文件md5.c

[cpp] view plaincopy

#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;

}

测试代码test.c

[cpp] view plaincopy

#include <stdio.h>

#include <stdlib.h>

#include "md5.h"

int main(int argc, char *argv[])

{

int i;

unsigned char encrypt[] ="admin";//21232f297a57a5a743894a0e4a801fc3

unsigned char decrypt[16];

MD5_CTX md5;

MD5Init(&md5);

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;

}