MD5摘要算法实现

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：

 1 #ifndef MD5_H
 2 #define MD5_H
 3  
 4 typedef struct
 5 {
 6     unsigned int count[2];
 7     unsigned int state[4];
 8     unsigned char buffer[64];   
 9 }MD5_CTX;
10  
11                          
12 #define F(x,y,z) ((x & y) | (~x & z))
13 #define G(x,y,z) ((x & z) | (y & ~z))
14 #define H(x,y,z) (x^y^z)
15 #define I(x,y,z) (y ^ (x | ~z))
16 #define ROTATE_LEFT(x,n) ((x << n) | (x >> (32-n)))
17 #define FF(a,b,c,d,x,s,ac) \
18           { \
19           a += F(b,c,d) + x + ac; \
20           a = ROTATE_LEFT(a,s); \
21           a += b; \
22           }
23 #define GG(a,b,c,d,x,s,ac) \
24           { \
25           a += G(b,c,d) + x + ac; \
26           a = ROTATE_LEFT(a,s); \
27           a += b; \
28           }
29 #define HH(a,b,c,d,x,s,ac) \
30           { \
31           a += H(b,c,d) + x + ac; \
32           a = ROTATE_LEFT(a,s); \
33           a += b; \
34           }
35 #define II(a,b,c,d,x,s,ac) \
36           { \
37           a += I(b,c,d) + x + ac; \
38           a = ROTATE_LEFT(a,s); \
39           a += b; \
40           }                                            
41 void MD5Init(MD5_CTX *context);
42 void MD5Update(MD5_CTX *context,unsigned char *input,unsigned int inputlen);
43 void MD5Final(MD5_CTX *context,unsigned char digest[16]);
44 void MD5Transform(unsigned int state[4],unsigned char block[64]);
45 void MD5Encode(unsigned char *output,unsigned int *input,unsigned int len);
46 void MD5Decode(unsigned int *output,unsigned char *input,unsigned int len);
47  
48 #endif

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