请用C++语言调用cryptto库编写一个字符串AESl加解密的函数

### 回答1：

可以使用以下C语言代码来编写一个字符串AES加解密的函数：#include <stdio.h>
#include <string.h>
#include <openssl/aes.h>

void aes_encrypt(char *plaintext, char *ciphertext)
{
AES_KEY enc_key;
unsigned char key[AES_BLOCK_SIZE];
unsigned char iv[AES_BLOCK_SIZE];

memset(key, 0x00, AES_BLOCK_SIZE);
memset(iv, 0x00, AES_BLOCK_SIZE);

AES_set_encrypt_key(key, AES_BLOCK_SIZE * 8, &enc_key);
AES_cbc_encrypt((unsigned char *)plaintext, (unsigned char *)ciphertext, strlen(plaintext), &enc_key, iv, AES_ENCRYPT);
}

void aes_decrypt(char *ciphertext, char *plaintext)
{
AES_KEY dec_key;
unsigned char key[AES_BLOCK_SIZE];
unsigned char iv[AES_BLOCK_SIZE];

memset(key, 0x00, AES_BLOCK_SIZE);
memset(iv, 0x00, AES_BLOCK_SIZE);

AES_set_decrypt_key(key, AES_BLOCK_SIZE * 8, &dec_key);
AES_cbc_encrypt((unsigned char *)ciphertext, (unsigned char *)plaintext, strlen(ciphertext), &dec_key, iv, AES_DECRYPT);
}

### 回答2：
使用C语言调用crypto库编写一个字符串AES加解密的函数，可以参考以下示例代码：

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

#define AES_KEY_SIZE 256
#define BLOCK_SIZE 16

// AES加密函数
int aes_encrypt(const unsigned char *plaintext, size_t plaintext_len, const unsigned char *key, unsigned char *ciphertext) {
    AES_KEY aes_key;

    if (AES_set_encrypt_key(key, AES_KEY_SIZE, &aes_key) < 0) {
        return -1; // 密钥设置失败
    }

    size_t num_blocks = (plaintext_len + BLOCK_SIZE - 1) / BLOCK_SIZE;
    unsigned char iv[BLOCK_SIZE];
    memset(iv, 0, sizeof(iv));

    for (size_t i = 0; i < num_blocks; i++) {
        AES_cbc_encrypt(plaintext + i * BLOCK_SIZE, ciphertext + i * BLOCK_SIZE, BLOCK_SIZE, &aes_key, iv, AES_ENCRYPT);
    }

    return num_blocks * BLOCK_SIZE;
}

// AES解密函数
int aes_decrypt(const unsigned char *ciphertext, size_t ciphertext_len, const unsigned char *key, unsigned char *plaintext) {
    AES_KEY aes_key;

    if (AES_set_decrypt_key(key, AES_KEY_SIZE, &aes_key) < 0) {
        return -1; // 密钥设置失败
    }

    size_t num_blocks = ciphertext_len / BLOCK_SIZE;
    unsigned char iv[BLOCK_SIZE];
    memset(iv, 0, sizeof(iv));

    for (size_t i = 0; i < num_blocks; i++) {
        AES_cbc_encrypt(ciphertext + i * BLOCK_SIZE, plaintext + i * BLOCK_SIZE, BLOCK_SIZE, &aes_key, iv, AES_DECRYPT);
    }

    return num_blocks * BLOCK_SIZE;
}

int main() {
    const unsigned char *plaintext = "Hello, world!";
    const unsigned char *key = "0123456789abcdef";

    size_t plaintext_len = strlen(plaintext);

    // 加密示例
    unsigned char ciphertext[plaintext_len];
    int encrypted_len = aes_encrypt(plaintext, plaintext_len, key, ciphertext);
    printf("Encrypted text: ");
    for (int i = 0; i < encrypted_len; ++i) {
        printf("%02x", ciphertext[i]);
    }
    printf("\n");

    // 解密示例
    unsigned char decrypted[encrypted_len];
    int decrypted_len = aes_decrypt(ciphertext, encrypted_len, key, decrypted);
    printf("Decrypted text: %s\n", decrypted);

    return 0;
}

上述代码使用了OpenSSL库提供的AES加密和解密函数，其中密钥长度为256位，加密模式为CBC，填充模式为PKCS#7。在示例中，我们加密了字符串"Hello, world!"，并将加密后的结果打印出来，然后再解密得到原始字符串。你可以按照自己的需求修改输入的明文和密钥。

### 回答3：
使用C语言调用crypto库编写一个字符串AES加解密的函数需要以下步骤：

1. 导入所需的头文件：

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

2. 定义AES加解密函数：

void aes_encrypt(char *plaintext, char *key, char *ciphertext) {
    AES_KEY aes_key;
    AES_set_encrypt_key(key, 128, &aes_key);
    AES_encrypt((unsigned char *)plaintext, (unsigned char *)ciphertext, &aes_key);
}

void aes_decrypt(char *ciphertext, char *key, char *plaintext) {
    AES_KEY aes_key;
    AES_set_decrypt_key(key, 128, &aes_key);
    AES_decrypt((unsigned char *)ciphertext, (unsigned char *)plaintext, &aes_key);
}

3. 在主函数中调用AES加解密函数：

int main() {
    char plaintext[16] = "Hello, World!";
    char key[16] = "abcdefghijklmnop";
    char ciphertext[16];
    char decrypted[16];

    aes_encrypt(plaintext, key, ciphertext);
    printf("Ciphertext: %s\n", ciphertext);

    aes_decrypt(ciphertext, key, decrypted);
    printf("Decrypted: %s\n", decrypted);

    return 0;
}

在这个例子中，使用了一个16字节的明文字符串"Hello, World!"和一个16字节的密钥字符串"abcdefghijklmnop"。首先调用aes_encrypt函数进行加密，然后打印输出密文。接下来调用aes_decrypt函数进行解密，最后打印输出解密后的明文。

需要注意的是，需要提前安装OpenSSL库并在编译时链接该库，例如使用以下命令进行编译：

gcc -o aes aes.c -lcrypto