急求 MD5的加密解密算法，用C++实现的源代码 高分答谢

Posted 2023-05-13

整不明白啊，麻烦哪位高手帮下忙啊~~~高分回谢的 %>_<% 谢谢

参考技术A 要代码，还是要相关的解释资料？

---------------------------------
要代码的话：

两个文件：
--------------------------
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);


--------------------------
就这两个文件。使用的时候把它们加入工程或者makefile，调用时包含md5.h即可，给个简单的例子，输入一个字符串然后计算它的md5值并输出，在VC6.0和GCC4.4下测试通过：

#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; i<16; ++i)

printf("%02X",digest[i]);

printf("\n");

return 0;
本回答被提问者和网友采纳

MD5是什么，怎么用着怪怪的

写作目的

通常我们在使用加密算法时，都是直接调用一个方法，比如Base64，直接把待加密的字符串给加密好了。对于某些使用公私钥的算法，最多再传入一段公钥即可。但是在使用MD5算法的时候，总是需要用到一个叫做Digest的东西，然后再经过一段有些神秘的代码把二进制转十六进制，才能获得想要的MD5“加密”后的结果。

我在之前用到MD5加密时，对此感到疑惑，但是仅仅把别人写好的代码拿来用，并未深究原因，知其然而不知其所以然。所以抽时间搞清楚了原因，并写下这篇文章作为记录。

 

MD5根本不是加密

MD5的全称是MD5消息摘要算法（MD5 Message-Digest Algorithm），是消息摘要算法的第五版。因此MD5的主要用途是用于验证消息传递途中的完整性，但并不隐藏消息内容。而我们日常所说的加密算法，一般是为了使消息在传输过程中不要被中间人查看或者篡改，并且消息的接收方式有方法解密并查看到完整的原始消息。

简单来说，加密后的信息是完整的，可以解密得到原始数据；摘要得到的信息不完整，无法恢复原始数据。所以MD5算法和加密算法的用途并不相同。严格来说，MD5并不能被称为加密算法。

 

MD5到底在做什么
顾名思义，消息摘要算法，“摘要”是其中重要的步骤，这也就提到了本文一开始所说的Digest的作用。

MD5在Java中的使用流程如下：
1. 创建一个MD5摘要算法的对象

MessageDigest md = MessageDigest.getInstance("MD5");

2. 将待处理的字符串转换为字节数组

byte[] byteMessage = message.getBytes();

3. 用摘要算法对象处理该字节数组，得到一个128位的摘要字节数组

byte[] buffer = md.digest(byteMessage);

4. 把数组每一字节（一个字节占八位）转换成16进制，得到原始消息的MD5值

String md5str = bytesToHex(buffer);

 

从上述过程中可以看出，MD5算法的处理过程明确分为摘要和将摘要字节拼接成十六进制串这两个阶段。

 

小结
弄清楚了MD5的含义，我也明白了MD5和加密没什么关系。以后提起MD5时，再不会顺口说出“MD5加密”这种话来了。