C 实现md5函数
测试了一下确实是可行的~
头文件：md5.h
1#ifndef MD5_H
2#define MD5_H
3
4typedef 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 }
41void MD5Init(MD5_CTX *context);
42void MD5Update(MD5_CTX *context,unsigned char *input,unsigned int inputlen);
43void MD5Final(MD5_CTX *context,unsigned char digest[16]);
44void MD5Transform(unsigned int state[4],unsigned char block[64]);
45void MD5Encode(unsigned char *output,unsigned int *input,unsigned int len);
46void MD5Decode(unsigned int *output,unsigned char *input,unsigned int len);
47
48#endif
49
源文件md5.c
1#include <memory.h>
2#include "md5.h"
3
4unsigned char PADDING[]={0x80,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
5 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
6 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
7 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
8
9void MD5Init(MD5_CTX *context)
10{
11 context->count[0] = 0;
12 context->count[1] = 0;
13 context->state[0] = 0x67452301;
14 context->state[1] = 0xEFCDAB89;
15 context->state[2] = 0x98BADCFE;
16 context->state[3] = 0x10325476;
17}
18void MD5Update(MD5_CTX *context,unsigned char *input,unsigned int inputlen)
19{
20 unsigned int i = 0,index = 0,partlen = 0;
21 index = (context->count[0] >> 3) & 0x3F;
22 partlen = 64 - index;
23 context->count[0] += inputlen << 3;
24 if(context->count[0] < (inputlen << 3))
25 context->count[1]++;
26 context->count[1] += inputlen >> 29;
27
28 if(inputlen >= partlen)
29 {
30 memcpy(&context->buffer[index],input,partlen);
31 MD5Transform(context->state,context->buffer);
32 for(i = partlen;i+64 <= inputlen;i+=64)
33 MD5Transform(context->state,&input[i]);
34 index = 0;
35 }
36 else
37 {
38 i = 0;
39 }
40 memcpy(&context->buffer[index],&input[i],inputlen-i);
41}
42void MD5Final(MD5_CTX *context,unsigned char digest[16])
43{
44 unsigned int index = 0,padlen = 0;
45 unsigned char bits[8];
46 index = (context->count[0] >> 3) & 0x3F;
47 padlen = (index < 56)?(56-index):(120-index);
48 MD5Encode(bits,context->count,8);
49 MD5Update(context,PADDING,padlen);
50 MD5Update(context,bits,8);
51 MD5Encode(digest,context->state,16);
52}
53void MD5Encode(unsigned char *output,unsigned int *input,unsigned int len)
54{
55 unsigned int i = 0,j = 0;
56 while(j < len)
57 {
58 output[j] = input[i] & 0xFF;
59 output[j+1] = (input[i] >> 8) & 0xFF;
60 output[j+2] = (input[i] >> 16) & 0xFF;
61 output[j+3] = (input[i] >> 24) & 0xFF;
62 i++;
63 j+=4;
64 }
65}
66void MD5Decode(unsigned int *output,unsigned char *input,unsigned int len)
67{
68 unsigned int i = 0,j = 0;
69 while(j < len)
70 {
71 output[i] = (input[j]) |
72 (input[j+1] << 8) |
73 (input[j+2] << 16) |
74 (input[j+3] << 24);
75 i++;
76 j+=4;
77 }
78}
79void MD5Transform(unsigned int state[4],unsigned char block[64])
80{
81 unsigned int a = state[0];
82 unsigned int b = state[1];
83 unsigned int c = state[2];
84 unsigned int d = state[3];
85 unsigned int x[64];
86 MD5Decode(x,block,64);
87 FF(a, b, c, d, x[ 0], 7, 0xd76aa478); /* 1 */
88 FF(d, a, b, c, x[ 1], 12, 0xe8c7b756); /* 2 */
89 FF(c, d, a, b, x[ 2], 17, 0x242070db); /* 3 */
90 FF(b, c, d, a, x[ 3], 22, 0xc1bdceee); /* 4 */
91 FF(a, b, c, d, x[ 4], 7, 0xf57c0faf); /* 5 */
92 FF(d, a, b, c, x[ 5], 12, 0x4787c62a); /* 6 */
93 FF(c, d, a, b, x[ 6], 17, 0xa8304613); /* 7 */
94 FF(b, c, d, a, x[ 7], 22, 0xfd469501); /* 8 */
95 FF(a, b, c, d, x[ 8], 7, 0x698098d8); /* 9 */
96 FF(d, a, b, c, x[ 9], 12, 0x8b44f7af); /* 10 */
97 FF(c, d, a, b, x[10], 17, 0xffff5bb1); /* 11 */
98 FF(b, c, d, a, x[11], 22, 0x895cd7be); /* 12 */
99 FF(a, b, c, d, x[12], 7, 0x6b901122); /* 13 */
100 FF(d, a, b, c, x[13], 12, 0xfd987193); /* 14 */
101 FF(c, d, a, b, x[14], 17, 0xa679438e); /* 15 */
102 FF(b, c, d, a, x[15], 22, 0x49b40821); /* 16 */
103
104 /* Round 2 */
105 GG(a, b, c, d, x[ 1], 5, 0xf61e2562); /* 17 */
106 GG(d, a, b, c, x[ 6], 9, 0xc040b340); /* 18 */
107 GG(c, d, a, b, x[11], 14, 0x265e5a51); /* 19 */
108 GG(b, c, d, a, x[ 0], 20, 0xe9b6c7aa); /* 20 */
109 GG(a, b, c, d, x[ 5], 5, 0xd62f105d); /* 21 */
110 GG(d, a, b, c, x[10], 9, 0x2441453); /* 22 */
111 GG(c, d, a, b, x[15], 14, 0xd8a1e681); /* 23 */
112 GG(b, c, d, a, x[ 4], 20, 0xe7d3fbc8); /* 24 */
113 GG(a, b, c, d, x[ 9], 5, 0x21e1cde6); /* 25 */
114 GG(d, a, b, c, x[14], 9, 0xc33707d6); /* 26 */
115 GG(c, d, a, b, x[ 3], 14, 0xf4d50d87); /* 27 */
116 GG(b, c, d, a, x[ 8], 20, 0x455a14ed); /* 28 */
117 GG(a, b, c, d, x[13], 5, 0xa9e3e905); /* 29 */
118 GG(d, a, b, c, x[ 2], 9, 0xfcefa3f8); /* 30 */
119 GG(c, d, a, b, x[ 7], 14, 0x676f02d9); /* 31 */
120 GG(b, c, d, a, x[12], 20, 0x8d2a4c8a); /* 32 */
121
122 /* Round 3 */
123 HH(a, b, c, d, x[ 5], 4, 0xfffa3942); /* 33 */
124 HH(d, a, b, c, x[ 8], 11, 0x8771f681); /* 34 */
125 HH(c, d, a, b, x[11], 16, 0x6d9d6122); /* 35 */
126 HH(b, c, d, a, x[14], 23, 0xfde5380c); /* 36 */
127 HH(a, b, c, d, x[ 1], 4, 0xa4beea44); /* 37 */
128 HH(d, a, b, c, x[ 4], 11, 0x4bdecfa9); /* 38 */
129 HH(c, d, a, b, x[ 7], 16, 0xf6bb4b60); /* 39 */
130 HH(b, c, d, a, x[10], 23, 0xbebfbc70); /* 40 */
131 HH(a, b, c, d, x[13], 4, 0x289b7ec6); /* 41 */
132 HH(d, a, b, c, x[ 0], 11, 0xeaa127fa); /* 42 */
133 HH(c, d, a, b, x[ 3], 16, 0xd4ef3085); /* 43 */
134 HH(b, c, d, a, x[ 6], 23, 0x4881d05); /* 44 */
135 HH(a, b, c, d, x[ 9], 4, 0xd9d4d039); /* 45 */
136 HH(d, a, b, c, x[12], 11, 0xe6db99e5); /* 46 */
137 HH(c, d, a, b, x[15], 16, 0x1fa27cf8); /* 47 */
138 HH(b, c, d, a, x[ 2], 23, 0xc4ac5665); /* 48 */
139
140 /* Round 4 */
141 II(a, b, c, d, x[ 0], 6, 0xf4292244); /* 49 */
142 II(d, a, b, c, x[ 7], 10, 0x432aff97); /* 50 */
143 II(c, d, a, b, x[14], 15, 0xab9423a7); /* 51 */
144 II(b, c, d, a, x[ 5], 21, 0xfc93a039); /* 52 */
145 II(a, b, c, d, x[12], 6, 0x655b59c3); /* 53 */
146 II(d, a, b, c, x[ 3], 10, 0x8f0ccc92); /* 54 */
147 II(c, d, a, b, x[10], 15, 0xffeff47d); /* 55 */
148 II(b, c, d, a, x[ 1], 21, 0x85845dd1); /* 56 */
149 II(a, b, c, d, x[ 8], 6, 0x6fa87e4f); /* 57 */
150 II(d, a, b, c, x[15], 10, 0xfe2ce6e0); /* 58 */
151 II(c, d, a, b, x[ 6], 15, 0xa3014314); /* 59 */
152 II(b, c, d, a, x[13], 21, 0x4e0811a1); /* 60 */
153 II(a, b, c, d, x[ 4], 6, 0xf7537e82); /* 61 */
154 II(d, a, b, c, x[11], 10, 0xbd3af235); /* 62 */
155 II(c, d, a, b, x[ 2], 15, 0x2ad7d2bb); /* 63 */
156 II(b, c, d, a, x[ 9], 21, 0xeb86d391); /* 64 */
157 state[0] += a;
158 state[1] += b;
159 state[2] += c;
160 state[3] += d;
161}
162
测试代码test.c
1#include <stdio.h>
2#include <stdlib.h>
3#include "md5.h"
4
5int main(int argc, char *argv[])
6{
7 int i;
8 unsigned char encrypt[] ="admin";//21232f297a57a5a743894a0e4a801fc3
9 unsigned char decrypt[16];
10 MD5_CTX md5;
11 MD5Init(&md5);
12 MD5Update(&md5,encrypt,strlen((char *)encrypt));
13 MD5Final(&md5,decrypt);
14 printf("加密前:%s\n加密后:",encrypt);
15 for(i=0;i<16;i++)
16 {
17 printf("%02x",decrypt[i]);
18 }
19
20 getchar();
21
22 return 0;
23}
24
评论 (1)
了解下了哈~~