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。
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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 */
1. md5.h：
＃pragma once
typedef unsigned long int UINT32;
typedef unsigned short int UINT16;
/× MD5 context. */
typedef struct {
UINT32 state[4]; /× state (ABCD) */
UINT32 count[2]; /× number of bits, modulo 2^64 (lsb first) */
unsigned char buffer[64]; /× input buffer */
} MD5_CTX;
void MD5Init (MD5_CTX *);
void MD5Update (MD5_CTX *, unsigned char *, unsigned int);
void MD5Final (unsigned char [16], MD5_CTX *);
——————————————————————————
2. md5.cpp：
＃include "md5.h"
＃include "memory.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
static void MD5Transform (UINT32 a[4], unsigned char b[64]);
static void Encode (unsigned char *, UINT32 *, unsigned int);
static void Decode (UINT32 *, unsigned char *, unsigned int);
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
};
＃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) + (UINT32)(ac);
(a) = ROTATE_LEFT ((a), (s));
(a) += (b);
}
＃define GG(a, b, c, d, x, s, ac) {
(a) += G ((b), (c), (d)) + (x) + (UINT32)(ac);
(a) = ROTATE_LEFT ((a), (s));
(a) += (b);
}
＃define HH(a, b, c, d, x, s, ac) {
(a) += H ((b), (c), (d)) + (x) + (UINT32)(ac);
(a) = ROTATE_LEFT ((a), (s));
(a) += (b);
}
＃define II(a, b, c, d, x, s, ac) {
(a) += I ((b), (c), (d)) + (x) + (UINT32)(ac);
(a) = ROTATE_LEFT ((a), (s));
(a) += (b);
}
void MD5Init (MD5_CTX *context)
{
context-count[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, index, partLen;
index = (unsigned int)((context-count[0] 3) 0x3F);
if ((context-count[0] += ((UINT32)inputLen 3))
((UINT32)inputLen 3))
context-count[1]++;
context-count[1] += ((UINT32)inputLen 29);
partLen = 64 - index;
if (inputLen = partLen) {
memcpy((unsigned char *)context-buffer[index], (unsigned char *)input, partLen);
MD5Transform (context-state, context-buffer);
for (i = partLen; i + 63 inputLen; i += 64)
MD5Transform (context-state, input[i]);
index = 0;
}
else
i = 0;
memcpy((unsigned char *)context-buffer[index], (unsigned char *)input[i],
inputLen-i);
}
void MD5Final (unsigned char digest[16], MD5_CTX * context)
{
unsigned char bits[8];
unsigned int index, padLen;
Encode (bits, context-count, 8);
index = (unsigned int)((context-count[0] 3) 0x3f);
padLen = (index 56) ? (56 - index) : (120 - index);
MD5Update (context, PADDING, padLen);
MD5Update (context, bits, 8);
Encode (digest, context-state, 16);
memset ((unsigned char *)context, 0, sizeof (*context));
}
static void MD5Transform (UINT32 state[4], unsigned char block[64])
{
UINT32 a = state[0], b = state[1], c = state[2], d = state[3], x[16];
Decode (x, block, 64);
/× Round 1 */
FF (a, b, c, d, x[ 0], S11, 0xd76aa478); /× 1 */
FF (d, a, b, c, x[ 1], S12, 0xe8c7b756); /× 2 */
FF (c, d, a, b, x[ 2], S13, 0x242070db); /× 3 */
FF (b, c, d, a, x[ 3], S14, 0xc1bdceee); /× 4 */
FF (a, b, c, d, x[ 4], S11, 0xf57c0faf); /× 5 */
FF (d, a, b, c, x[ 5], S12, 0x4787c62a); /× 6 */
FF (c, d, a, b, x[ 6], S13, 0xa8304613); /× 7 */
FF (b, c, d, a, x[ 7], S14, 0xfd469501); /× 8 */
FF (a, b, c, d, x[ 8], S11, 0x698098d8); /× 9 */
FF (d, a, b, c, x[ 9], S12, 0x8b44f7af); /× 10 */
FF (c, d, a, b, x[10], S13, 0xffff5bb1); /× 11 */
FF (b, c, d, a, x[11], S14, 0x895cd7be); /× 12 */
FF (a, b, c, d, x[12], S11, 0x6b901122); /× 13 */
FF (d, a, b, c, x[13], S12, 0xfd987193); /× 14 */
FF (c, d, a, b, x[14], S13, 0xa679438e); /× 15 */
FF (b, c, d, a, x[15], S14, 0x49b40821); /× 16 */
/× Round 2 */
GG (a, b, c, d, x[ 1], S21, 0xf61e2562); /× 17 */
GG (d, a, b, c, x[ 6], S22, 0xc040b340); /× 18 */
GG (c, d, a, b, x[11], S23, 0x265e5a51); /× 19 */
GG (b, c, d, a, x[ 0], S24, 0xe9b6c7aa); /× 20 */
GG (a, b, c, d, x[ 5], S21, 0xd62f105d); /× 21 */
GG (d, a, b, c, x[10], S22, 0x2441453); /× 22 */
GG (c, d, a, b, x[15], S23, 0xd8a1e681); /× 23 */
GG (b, c, d, a, x[ 4], S24, 0xe7d3fbc8); /× 24 */
GG (a, b, c, d, x[ 9], S21, 0x21e1cde6); /× 25 */
GG (d, a, b, c, x[14], S22, 0xc33707d6); /× 26 */
GG (c, d, a, b, x[ 3], S23, 0xf4d50d87); /× 27 */
GG (b, c, d, a, x[ 8], S24, 0x455a14ed); /× 28 */
GG (a, b, c, d, x[13], S21, 0xa9e3e905); /× 29 */
GG (d, a, b, c, x[ 2], S22, 0xfcefa3f8); /× 30 */
GG (c, d, a, b, x[ 7], S23, 0x676f02d9); /× 31 */
GG (b, c, d, a, x[12], S24, 0x8d2a4c8a); /× 32 */
/× Round 3 */
HH (a, b, c, d, x[ 5], S31, 0xfffa3942); /× 33 */
HH (d, a, b, c, x[ 8], S32, 0x8771f681); /× 34 */
HH (c, d, a, b, x[11], S33, 0x6d9d6122); /× 35 */
HH (b, c, d, a, x[14], S34, 0xfde5380c); /× 36 */
HH (a, b, c, d, x[ 1], S31, 0xa4beea44); /× 37 */
HH (d, a, b, c, x[ 4], S32, 0x4bdecfa9); /× 38 */
HH (c, d, a, b, x[ 7], S33, 0xf6bb4b60); /× 39 */
HH (b, c, d, a, x[10], S34, 0xbebfbc70); /× 40 */
HH (a, b, c, d, x[13], S31, 0x289b7ec6); /× 41 */
HH (d, a, b, c, x[ 0], S32, 0xeaa127fa); /× 42 */
HH (c, d, a, b, x[ 3], S33, 0xd4ef3085); /× 43 */
HH (b, c, d, a, x[ 6], S34, 0x4881d05); /× 44 */
HH (a, b, c, d, x[ 9], S31, 0xd9d4d039); /× 45 */
HH (d, a, b, c, x[12], S32, 0xe6db99e5); /× 46 */
HH (c, d, a, b, x[15], S33, 0x1fa27cf8); /× 47 */
HH (b, c, d, a, x[ 2], S34, 0xc4ac5665); /× 48 */
/× Round 4 */
II (a, b, c, d, x[ 0], S41, 0xf4292244); /× 49 */
II (d, a, b, c, x[ 7], S42, 0x432aff97); /× 50 */
II (c, d, a, b, x[14], S43, 0xab9423a7); /× 51 */
II (b, c, d, a, x[ 5], S44, 0xfc93a039); /× 52 */
II (a, b, c, d, x[12], S41, 0x655b59c3); /× 53 */
II (d, a, b, c, x[ 3], S42, 0x8f0ccc92); /× 54 */
II (c, d, a, b, x[10], S43, 0xffeff47d); /× 55 */
II (b, c, d, a, x[ 1], S44, 0x85845dd1); /× 56 */
II (a, b, c, d, x[ 8], S41, 0x6fa87e4f); /× 57 */
II (d, a, b, c, x[15], S42, 0xfe2ce6e0); /× 58 */
II (c, d, a, b, x[ 6], S43, 0xa3014314); /× 59 */
II (b, c, d, a, x[13], S44, 0x4e0811a1); /× 60 */
II (a, b, c, d, x[ 4], S41, 0xf7537e82); /× 61 */
II (d, a, b, c, x[11], S42, 0xbd3af235); /× 62 */
II (c, d, a, b, x[ 2], S43, 0x2ad7d2bb); /× 63 */
II (b, c, d, a, x[ 9], S44, 0xeb86d391); /× 64 */
state[0] += a;
state[1] += b;
state[2] += c;
state[3] += d;
memset ((unsigned char *)x, 0, sizeof (x));
}
static void Encode (unsigned char *output, UINT32 *input, unsigned int len)
{
unsigned int i, j;
for (i = 0, j = 0; j len; i++, j += 4) {
output[j] = (unsigned char)(input[i] 0xff);
output[j+1] = (unsigned char)((input[i] 8) 0xff);
output[j+2] = (unsigned char)((input[i] 16) 0xff);
output[j+3] = (unsigned char)((input[i] 24) 0xff);
}
}
static void Decode (UINT32 *output, unsigned char *input, unsigned int len)
{
unsigned int i, j;
for (i = 0, j = 0; j len; i++, j += 4)
output[i] = ((UINT32)input[j]) | (((UINT32)input[j+1]) 8) |
(((UINT32)input[j+2]) 16) | (((UINT32)input[j+3]) 24);
}
——————————————————————————
＃include stdio.h
＃include string.h
＃include "md5.h"
int main ()
{
char tmp[128];
unsigned char digest[16];
MD5_CTX context;
scanf("%s",tmp);
MD5Init (context);
MD5Update (context, (unsigned char*)tmp, strlen(tmp));
MD5Final (digest,context);
printf("MD5Value:");
for(int i=0; i16; ++i)
{
printf("%02X",digest[i]);
}
printf(" ");
return 0;
}
#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
#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;
}
