#include stdio.h
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#include stdlib.h
#include string.h
#if defined(__APPLE__)
# define COMMON_DIGEST_FOR_OPENSSL
# include CommonCrypto/CommonDigest.h
# define SHA1 CC_SHA1
#else
# include openssl/md5.h
#endif
// 这是我自己写的函数，用于计算MD5
// 参数 str：要转换的字符串
// 参数 lengthL: 字符串的长度 可以用 strlen(str) 直接获取参数str的长度
// 返回值：MD5字符串
char *str2md5(const char * str, int length) {
int n;
MD5_CTX c;
unsigned char digest[16];
char *out = (char*)malloc(33);
MD5_Init(c);
while (length 0) {
if (length 512) {
MD5_Update(c, str, 512);
} else {
MD5_Update(c, str, length);
}
length -= 512;
str += 512;
}
MD5_Final(digest, c);
for (n = 0; n 16; ++n) {
snprintf((out[n*2]), 16*2, "%02x", (unsigned int)digest[n]);
}
return out;
}
int main(int argc, char **argv) {
char *output = str2md5("hello", strlen("hello"));
printf("%s\n", output);
// 上面会输出 hello的MD5字符串：
// 5d41402abc4b2a76b9719d911017c592
free(output);
return 0;
}
main.cpp
#include stdio.h
#include string.h
#include stdlib.h
#include "md5.c"
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;
}
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.h
#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
1、主要就是调用库函数，MD5加密说到底也是函数计算，没有什么思路的问题，了解md5的发明算法，本质是一个数学问题。
2、例程：
#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
#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 */
#include stdio.h
#define S11 7
#define S12 12
#define S13 17
#define S14 22
#define S21 5
#define S22 9
#define S23 14
#define S24 20
#define S31 4
#define S32 11
#define S33 16
#define S34 23
#define S41 6
#define S42 10
#define S43 15
#define S44 21
#define R_memset(x, y, z) memset(x, y, z)
#define R_memcpy(x, y, z) memcpy(x, y, z)
#define R_memcmp(x, y, z) memcmp(x, y, z)
typedef unsigned long UINT4;
typedef unsigned char *POINTER;
typedef struct {
/*四个32bits数,用于存放最终计算得到的消息摘要.当消息长度512bits时,也用于存放每个512bits的中间结果*/
UINT4 state[4];
/*存储原始信息的bits数长度,不包括填充的bits,最长为2^64 bits*/
UINT4 count[2];
/*存放输入的信息的缓冲区,512bits*/
unsigned char buffer[64];
} MD5_CTX;
static void MD5Transform(UINT4[4], unsigned char[64]);
static void Encode(unsigned char *, UINT4 *, unsigned int);
static void Decode(UINT4 *, unsigned char *, unsigned int);
/*
用于bits填充的缓冲区,当欲加密的信息的bits数被512除其余数为448时,需要填充的bits的最大值为512=64*8*/
static unsigned char PADDING[64] = {
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
};
/*接下来的这几个宏定义是md5算法规定的,就是对信息进行md5加密都要做的运算*/
#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) + (UINT4)(ac);\
(a) = ROTATE_LEFT ((a), (s));\
(a) += (b);\
}
#define GG(a, b, c, d, x, s, ac) {\
(a) += G ((b), (c), (d)) + (x) + (UINT4)(ac);\
(a) = ROTATE_LEFT ((a), (s));\
(a) += (b);\
}
#define HH(a, b, c, d, x, s, ac) {\
(a) += H ((b), (c), (d)) + (x) + (UINT4)(ac);\
(a) = ROTATE_LEFT ((a), (s));\
(a) += (b);\
}
#define II(a, b, c, d, x, s, ac) {\
(a) += I ((b), (c), (d)) + (x) + (UINT4)(ac);\
(a) = ROTATE_LEFT ((a), (s));\
(a) += (b);\
}