linux 安装crypto库

sudo apt update
sudo apt install libssl-dev

sudo yum update
sudo yum install openssl-devel

#include <openssl/evp.h>
#include <string.h>

void handleErrors() {
    // 错误处理代码
}

int encrypt(unsigned char *plaintext, int plaintext_len, unsigned char *key,
            unsigned char *iv, unsigned char *ciphertext) {
    EVP_CIPHER_CTX *ctx;
    int len;
    int ciphertext_len;

    if(!(ctx = EVP_CIPHER_CTX_new())) handleErrors();
    if(1 != EVP_EncryptInit_ex(ctx, EVP_aes_256_cbc(), NULL, key, iv)) handleErrors();
    if(1 != EVP_EncryptUpdate(ctx, ciphertext, &len, plaintext, plaintext_len)) handleErrors();
    ciphertext_len = len;
    if(1 != EVP_EncryptFinal_ex(ctx, ciphertext + len, &len)) handleErrors();
    ciphertext_len += len;
    EVP_CIPHER_CTX_free(ctx);
    return ciphertext_len;
}

int decrypt(unsigned char *ciphertext, int ciphertext_len, unsigned char *key,
            unsigned char *iv, unsigned char *plaintext) {
    EVP_CIPHER_CTX *ctx;
    int len;
    int plaintext_len;

    if(!(ctx = EVP_CIPHER_CTX_new())) handleErrors();
    if(1 != EVP_DecryptInit_ex(ctx, EVP_aes_256_cbc(), NULL, key, iv)) handleErrors();
    if(1 != EVP_DecryptUpdate(ctx, plaintext, &len, ciphertext, ciphertext_len)) handleErrors();
    plaintext_len = len;
    if(1 != EVP_DecryptFinal_ex(ctx, plaintext + len, &len)) handleErrors();
    plaintext_len += len;
    EVP_CIPHER_CTX_free(ctx);
    return plaintext_len;
}