des算法c语言实现

DES（Data Encryption Standard）是一种常见的对称加密算法，用于保护数据的机密性。下面是一个使用C语言实现DES算法的简单示例：

#include <stdio.h>
#include <stdint.h>

// 定义DES算法需要的常量

// 初始置换矩阵IP
static const int IP[] = { 58, 50, 42, 34, 26, 18, 10, 2,
                          60, 52, 44, 36, 28, 20, 12, 4,
                          62, 54, 46, 38, 30, 22, 14, 6,
                          64, 56, 48, 40, 32, 24, 16, 8,
                          57, 49, 41, 33, 25, 17, 9, 1,
                          59, 51, 43, 35, 27, 19, 11, 3,
                          61, 53, 45, 37, 29, 21, 13, 5,
                          63, 55, 47, 39, 31, 23, 15, 7 };

// 逆初始置换矩阵IP^-1
static const int IPInv[] = { 40, 8, 48, 16, 56, 24, 64, 32,
                             39, 7, 47, 15, 55, 23, 63, 31,
                             38, 6, 46, 14, 54, 22, 62, 30,
                             37, 5, 45, 13, 53, 21, 61, 29,
                             36, 4, 44, 12, 52, 20, 60, 28,
                             35, 3, 43, 11, 51, 19, 59, 27,
                             34, 2, 42, 10, 50, 18, 58, 26,
                             33, 1, 41, 9, 49, 17, 57, 25 };

// ... 其他常量和S盒等

// DES加密函数
void des_encrypt(uint64_t* plainText, uint64_t* key, uint64_t* cipherText) {
    // ... 实现DES加密的过程
}

int main() {
    uint64_t plainText = 0x0123456789ABCDEF; // 待加密的明文
    uint64_t key = 0x133457799BBCDFF1; // 密钥
    uint64_t cipherText = 0; // 加密后的密文

    des_encrypt(&plainText, &key, &cipherText);

    printf("Cipher text: %016llx\n", cipherText);

    return 0;
}

以上代码仅为简单示例，实际的DES算法涉及到更多的细节和步骤，在实际使用中需要做更多的安全性和性能优化考虑。