$data = 'Olá, Wallace!';

$encryption_key = openssl_random_pseudo_bytes(32);

$iv = openssl_random_pseudo_bytes(openssl_cipher_iv_length('AES-256-CBC'));

$encrypted = openssl_encrypt($data, 'AES-256-CBC', $encryption_key, 0, $iv);

if (false === $encrypted) {

    var_dump(openssl_error_string());

    exit;
}