C语言实现获取文件MD5值
#include
#include
#include
typedef unsigned char uint8;
typedef unsigned int uint32;
// MD5常量定义
const uint32 MD5_CONSTANTS[] = {
0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee,
0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501,
0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be,
0x6b901122, 0xfd987193, 0xa679438e, 0x49b40821,
0xf61e2562, 0xc040b340, 0x265e5a51, 0xe9b6c7aa,
0xd62f105d, 0x02441453, 0xd8a1e681, 0xe7d3fbc8,
0x21e1cde6, 0xc33707d6, 0xf4d50d87, 0x455a14ed,
0xa9e3e905, 0xfcefa3f8, 0x676f02d9, 0x8d2a4c8a,
0xfffa3942, 0x8771f681, 0x6d9d6122, 0xfde5380c,
0xa4beea44, 0x4bdecfa9, 0xf6bb4b60, 0xbebfbc70,
0x289b7ec6, 0xeaa127fa, 0xd4ef3085, 0x04881d05,
0xd9d4d039, 0xe6db99e5, 0x1fa27cf8, 0xc4ac5665,
0xf4292244, 0x432aff97, 0xab9423a7, 0xfc93a039,
0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1,
0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1,
0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391
};
// 循环左移
#define LEFT_ROTATE(x, n) (((x) << (n)) | ((x) >> (32 - (n))))
// 转换为大端字节序
void to_big_endian(uint32 value, uint8* buffer) {
buffer[0] = (uint8)(value & 0xff);
buffer[1] = (uint8)((value >> 8) & 0xff);
buffer[2] = (uint8)((value >> 16) & 0xff);
buffer[3] = (uint8)((value >> 24) & 0xff);
}
// 处理消息块
void process_block(const uint8* block, uint32* state) {
uint32 a = state[0];
uint32 b = state[1];
uint32 c = state[2];
uint32 d = state[3];
uint32 m[16];
// 将消息块划分为16个32位字，并进行字节序转换
for (int i = 0; i < 16; i++) {
m[i] = (((uint32)block[i * 4 + 0]) << 0) |
(((uint32)block[i * 4 + 1]) << 8) |
(((uint32)block[i * 4 + 2]) << 16) |
(((uint32)block[i * 4 + 3]) << 24);
}
// MD5循环运算
for (int i = 0; i < 64; i++) {
uint32 f, g;
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;
}
uint32 temp = d;
d = c;
c = b;
b = b + LEFT_ROTATE((a + f + MD5_CONSTANTS[i] + m[g]), 7);
a = temp;
}
// 更新状态
state[0] += a;
state[1] += b;
state[2] += c;
state[3] += d;
}
// 计算MD5值
void calculate_md5(const uint8* message, size_t length, uint8* digest) {
// 初始化状态
uint32 state[4] = { 0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476 };
// 填充消息
size_t padded_length = ((length + 8) / 64 + 1) * 64;
uint8* padded_message = (uint8*)calloc(padded_length, 1);
memcpy(padded_message, message, length);
padded_message[length] = 0x80; // 添加一个1
to_big_endian((uint32)(length * 8), padded_message + padded_length - 8); // 添加长度（以位为单位）
// 处理消息块
for (size_t i = 0; i < padded_length; i += 64) {
process_block(padded_message + i, state);
}
// 生成摘要
for (int i = 0; i < 4; i++) {
to_big_endian(state[i], digest + i * 4);
}
free(padded_message);
}
// 打印MD5值
void print_md5(const uint8* digest) {
for (int i = 0; i < 16; i++) {
printf("%02x", digest[i]);
}
printf("
");
}
int main() {
const char* message = "Hello, World!";
size_t length = strlen(message);
uint8 digest[16];
calculate_md5((const uint8*)message, length, digest);
printf("MD5: ");
print_md5(digest);
return 0;
}