C语言求文件MD5的函数用法?

Question

byte[] data = new byte[DATA_SIZE]; 
MD5 md5 = new MD5CryptoServiceProvider(); 
byte[] result = md5.ComputeHash(data); 
这个函数怎么用？。。

Answer 1

#ifndef&nbsp;MD5_H#define&nbsp;MD5_Htypedef struct{unsigned int count[2];unsigned int state[4];unsigned char buffer[64];}MD5_CTX;#define&nbsp;F(x,y,z) ((x & y) | (~x & z))#define&nbsp;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&nbsp;FF(a,b,c,d,x,s,ac) \{ \a += F(b,c,d) + x + ac; \a = ROTATE_LEFT(a,s); \a += b; \}#define&nbsp;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#include <memory.h>#include "md5.h"unsigned char&nbsp;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 */

Answer 2

0x2000 0000在这里是16进制数 转换成十进制数是536870912bit = 67108864 BYTE = 65536 KB = 64MB/* flen[1]=len/0x20000000; //flen单位是bit */这行指令做的是 看那个被打开的文件的长度是64兆的多少倍 并且把计算出的结果（倍数）放到array flen[1]里（file length）并且存进去的是个整数 文件长度是个很长的很奇怪的数 除个536870912这么个怪数肯定不会是个整数（至少大多情况下）所以有了下面这一行指令/* flen[0]=(len%0x20000000)*8; */这行指令把file length除64MB这个数的余数提出 并且乘了8（即除以64MB 余数* 8 让BYTE单位变成bit单位） 为程序的后面做运算做铺垫或者准备并且存在了flen[0]里这个程序不全 我想提问题的人应该有全的版本 我能给的帮助就这么多 希望能帮到你:)

Answer 3

冒号后面的叫初始化列表，你也可以在后面的大括号里写weight=0，效果是一样的，就是你这个默认构造函数调用是，对象里的weight被初始化为0了，不过有些东西只能在初始化表里初始化，比如：引用什么的，具体你看《primer&nbsp;c++》里有详细介绍