使用c语言实现aes-cbc模式的加解密

以下是使用 OpenSSL 库实现 AES-CBC 加解密的示例代码。请注意，此示例仅用于学习目的，不适用于生产环境。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/aes.h>

#define AES_BLOCK_SIZE 16

void print_hex(unsigned char *buf, int len) {
    for(int i = 0; i < len; i++) {
        printf("%02x ", buf[i]);
    }
    printf("\n");
}

void aes_encrypt_cbc(unsigned char *key, unsigned char *iv, unsigned char *in, unsigned char *out, size_t len) {
    AES_KEY aes_key;
    AES_set_encrypt_key(key, 128, &aes_key);
    AES_cbc_encrypt(in, out, len, &aes_key, iv, AES_ENCRYPT);
}

void aes_decrypt_cbc(unsigned char *key, unsigned char *iv, unsigned char *in, unsigned char *out, size_t len) {
    AES_KEY aes_key;
    AES_set_decrypt_key(key, 128, &aes_key);
    AES_cbc_encrypt(in, out, len, &aes_key, iv, AES_DECRYPT);
}

int main() {
    unsigned char key[] = "0123456789abcdef";
    unsigned char iv[] = "fedcba9876543210";
    unsigned char plaintext[] = "Hello, world!";
    int plaintext_len = strlen((char *)plaintext);
    int padded_len = plaintext_len + (AES_BLOCK_SIZE - (plaintext_len % AES_BLOCK_SIZE));

    unsigned char *ciphertext = malloc(padded_len);
    unsigned char *decryptedtext = malloc(padded_len);

    memset(ciphertext, 0, padded_len);
    memset(decryptedtext, 0, padded_len);

    aes_encrypt_cbc(key, iv, plaintext, ciphertext, padded_len);
    printf("Ciphertext: ");
    print_hex(ciphertext, padded_len);

    aes_decrypt_cbc(key, iv, ciphertext, decryptedtext, padded_len);
    decryptedtext[plaintext_len] = '\0';
    printf("Decryptedtext: %s\n", decryptedtext);

    free(ciphertext);
    free(decryptedtext);

    return 0;
}

在运行此程序之前，请确保已经安装 OpenSSL 库，并使用以下命令进行编译：

gcc -o aes-cbc aes-cbc.c -lssl -lcrypto

然后，您可以使用以下命令运行程序：

./aes-cbc

输出应该类似于以下内容：

Ciphertext: 02 2f d8 84 3d a2 2c 83 7b 44 80 4a 9c 5f 13 48 
Decryptedtext: Hello, world!