linux crypto 安装

sudo apt update
sudo apt install openssl libssl-dev

sudo yum update
sudo yum install openssl openssl-devel

sudo dnf update
sudo dnf install openssl openssl-devel

# 检查是否安装
openssl version

# 如果未安装，按照上述步骤安装
# 如果已安装但找不到命令，可能需要添加库路径到环境变量
export LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH

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

void handleErrors() {
    ERR_print_errors_fp(stderr);
    abort();
}

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;
}

int main() {
    unsigned char key[32] = "01234567890123456789012345678901";
    unsigned char iv[16] = "0123456789012345";
    unsigned char plaintext[] = "This is a secret message";
    unsigned char ciphertext[128];
    unsigned char decryptedtext[128];

    int decryptedtext_len, ciphertext_len;

    ciphertext_len = encrypt (plaintext, strlen ((char *)plaintext), key, iv, ciphertext);
    decryptedtext_len = decrypt(ciphertext, ciphertext_len, key, iv, decryptedtext);

    decryptedtext[decryptedtext_len] = '\0';
    printf("Decrypted text is: %s\n", decryptedtext);

    return 0;
}

gcc -o test_encryption test_encryption.c -lssl -lcrypto