Simple symmetric encryption / decryption using AES CBC, pre-shared 16 bytes key and random 16 bytes initialisation vector

encrypt_decrypt_cbc.pike

#!/usr/bin/pike

// Pre-shared key. Should be 16 bytes, kept secret
string key = "secret16byteskey";
// Message to encode 
string msg_from = "What's your name, James?";
// Initialisation vector. Should be 16 bytes, randomly generated for each iteration
string iv = random_string(16);

int main(int argc, array(string) argv)
{
        write("iv  : %O\nkey : %O\nmsg : %O\n", iv, key, msg_from);

        // encrypt
        object encrypter = Crypto.Buffer(Crypto.CBC(Crypto.AES)->set_iv(iv));
        encrypter->set_encrypt_key(key);
        string cipher_raw = encrypter->crypt(msg_from);
        cipher_raw += encrypter->pad();

        write("raw : %O\n", cipher_raw);
        write("hex : %O\n", String.string2hex(cipher_raw));
        write("b64 : %O\n", MIME.encode_base64(cipher_raw));
        
        //decrypt
        object decrypter = Crypto.Buffer(Crypto.CBC(Crypto.AES)->set_iv(iv));
        decrypter->set_decrypt_key(key);
        string msg_to = decrypter->unpad(cipher_raw);

        write("msg : %O\n", msg_to);

        return 0;
}