c 实现md5加密
时间: 2023-08-09 18:05:08 浏览: 49
MD5是一种哈希算法,可以将任意长度的数据映射为128位的哈希值。下面是C语言实现MD5加密的示例代码:
```c
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#define LEFTROTATE(x, c) (((x) << (c)) | ((x) >> (32 - (c))))
void md5(uint8_t *initial_msg, size_t initial_len, uint8_t *digest) {
//定义变量
uint32_t h0, h1, h2, h3;
uint8_t *msg = NULL;
uint32_t *chunks = NULL;
size_t new_len, offset;
uint32_t a, b, c, d, f, g, temp;
uint32_t r[] = {
7, 12, 17, 22,
7, 12, 17, 22,
7, 12, 17, 22,
7, 12, 17, 22
};
uint32_t k[] = {
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
};
//初始化变量
h0 = 0x67452301;
h1 = 0xefcdab89;
h2 = 0x98badcfe;
h3 = 0x10325476;
//将消息填充为512位块的倍数
new_len = ((((initial_len + 8) / 64) + 1) * 64) - 8;
msg = calloc(new_len + 64, 1);
memcpy(msg, initial_msg, initial_len);
msg[initial_len] = 128;
offset = initial_len + 1;
while (offset < new_len) {
msg[offset] = 0;
offset++;
}
*((uint64_t *)(msg + new_len)) = (uint64_t)initial_len * 8;
//处理消息
chunks = (uint32_t *)msg;
for (offset = 0; offset < new_len; offset += 64) {
a = h0;
b = h1;
c = h2;
d = h3;
for (int i = 0; i < 64; i++) {
if (i < 16) {
f = (b & c) | ((~b) & d);
g = i;
} else if (i < 32) {
f = (d & b) | ((~d) & c);
g = (5 * i + 1) % 16;
} else if (i < 48) {
f = b ^ c ^ d;
g = (3 * i + 5) % 16;
} else {
f = c ^ (b | (~d));
g = (7 * i) % 16;
}
temp = d;
d = c;
c = b;
b = b + LEFTROTATE((a + f + k[i] + chunks[g]), r[i]);
a = temp;
}
h0 += a;
h1 += b;
h2 += c;
h3 += d;
}
//将结果转化为字节数组
memcpy(digest, &h0, 4);
memcpy(digest + 4, &h1, 4);
memcpy(digest + 8, &h2, 4);
memcpy(digest + 12, &h3, 4);
//释放内存
free(msg);
}
int main() {
//测试
char *msg = "hello world";
uint8_t digest[16];
md5((uint8_t *)msg, strlen(msg), digest);
for (int i = 0; i < 16; i++) {
printf("%02x", digest[i]);
}
printf("\n");
return 0;
}
```
注意,这里的MD5实现仅供学习和参考,实际应用中应该使用更安全的加密算法。