用c++写一个MD5算法
时间: 2023-05-12 07:06:54 浏览: 70
可以使用以下代码实现MD5算法:
#include <stdio.h>
#include <string.h>
#include <openssl/md5.h>
int main()
{
char str[] = "Hello, world!";
unsigned char digest[MD5_DIGEST_LENGTH];
MD5((unsigned char*)&str, strlen(str), digest);
char md5string[33];
for(int i = 0; i < 16; i++)
sprintf(&md5string[i*2], "%02x", (unsigned int)digest[i]);
printf("MD5 hash of string '%s' is: %s\n", str, md5string);
return 0;
}
这段代码使用了OpenSSL库中的MD5函数来计算字符串的MD5哈希值,并将结果以十六进制字符串的形式输出。
相关问题
用c++写一个md5算法
以下是C++实现的MD5算法代码:
```c++
#include <iostream>
#include <cstring>
#include <cstdio>
using namespace std;
// 定义MD5中用到的常量
const unsigned int S[64] = {
7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22,
5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20,
4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23,
6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21
};
const unsigned int K[64] = {
0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
0xd62f105d, 0x2441453, 0xd8a1e681, 0xe7d3fbc8,
0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x4881d05,
0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391
};
// 定义循环左移函数
inline unsigned int leftRotate(unsigned int x, unsigned int n) {
return (x << n) | (x >> (32 - n));
}
// 主函数,计算MD5值
void md5(unsigned char* str, unsigned int length, unsigned char* result) {
// 定义初始值
unsigned int a0 = 0x67452301;
unsigned int b0 = 0xefcdab89;
unsigned int c0 = 0x98badcfe;
unsigned int d0 = 0x10325476;
// 计算填充长度
unsigned int newLength = ((length + 8) / 64 + 1) * 64;
unsigned char* newStr = new unsigned char[newLength];
memcpy(newStr, str, length);
newStr[length] = 0x80;
for (unsigned int i = length + 1; i < newLength - 8; i++) {
newStr[i] = 0;
}
memcpy(newStr + newLength - 8, &length, 4);
// 循环计算
for (unsigned int i = 0; i < newLength; i += 64) {
unsigned int A = a0;
unsigned int B = b0;
unsigned int C = c0;
unsigned int D = d0;
unsigned int* X = (unsigned int*)(newStr + i);
for (unsigned int j = 0; j < 64; j++) {
unsigned int F, g;
if (j < 16) {
F = (B & C) | ((~B) & D);
g = j;
} else if (j < 32) {
F = (D & B) | ((~D) & C);
g = (5 * j + 1) % 16;
} else if (j < 48) {
F = B ^ C ^ D;
g = (3 * j + 5) % 16;
} else {
F = C ^ (B | (~D));
g = (7 * j) % 16;
}
unsigned int tmp = D;
D = C;
C = B;
B = B + leftRotate((A + F + K[j] + X[g]), S[j]);
A = tmp;
}
a0 += A;
b0 += B;
c0 += C;
d0 += D;
}
memcpy(result, &a0, 4);
memcpy(result + 4, &b0, 4);
memcpy(result + 8, &c0, 4);
memcpy(result + 12, &d0, 4);
delete[] newStr;
}
// 测试样例
int main() {
unsigned char str[] = "hello world";
unsigned char result[16];
md5(str, strlen((char*)str), result);
for (int i = 0; i < 16; i++) {
printf("%02x", result[i]);
}
printf("\n");
return 0;
}
```
该代码实现了MD5算法的计算过程,可以通过输入字符串来计算对应的MD5值。
用c++实现md5算法的填充部分
要实现MD5算法的填充部分,首先需要了解MD5算法的基本原理和规则。
MD5(Message-Digest Algorithm 5)是一种广泛使用的哈希函数,用于确保数据的完整性和一致性。它将任意长度的数据块作为输入,经过一系列复杂的计算得到一个128位的哈希值。
在MD5算法中,填充部分是为了将输入数据块的长度扩展为64的倍数。填充的规则如下:
1. 将原始数据块的长度与64取余,得到余数R。
2. 定义S为64减去R的值(即S = 64 - R)。
3. 在原始数据块的末尾添加一个1和S个0。如果S小于8,还需要在数据块的末尾添加64位的表示原始数据块长度的二进制数。
以下为用C语言实现MD5算法的填充部分的示例代码:
```c
#include <stdio.h>
#include <string.h>
void md5_padding(char *data, int length) {
int remain = length % 64;
int padding_size = 64 - remain;
// Add 1 and S zeros
data[length] = 0x80; // Add 1 in binary as 0x80 in hex
memset(data + length + 1, 0, padding_size - 1);
// If padding_size is less than 8, add binary value of length to the end of data
if (padding_size < 8) {
uint64_t bit_length = length * 8;
memcpy(data + length + padding_size, &bit_length, 8);
}
}
int main() {
char data[100] = "Hello, World!"; // Example input data
int length = strlen(data);
md5_padding(data, length);
printf("Padded Data: %s\n", data);
return 0;
}
```
在以上示例代码中,我们首先确定了填充的大小padding_size,并利用memset函数将末尾的0填充进原始数据。然后,根据padding_size是否小于8来决定是否在末尾添加表示原始数据长度的二进制数。
最后,我们输出填充后的数据data,即得到了完成填充部分的MD5算法实现。