PHPSecureSession\SecureHandler::encrypt PHP Method

    protected function encrypt($data, $key)
    {
        $iv = random_bytes(16);
        // AES block size in CBC mode
        // Encryption
        $ciphertext = openssl_encrypt($data, 'AES-256-CBC', mb_substr($key, 0, 32, '8bit'), OPENSSL_RAW_DATA, $iv);
        // Authentication
        $hmac = hash_hmac('SHA256', $iv . $ciphertext, mb_substr($key, 32, null, '8bit'), true);
        return $hmac . $iv . $ciphertext;
    }