// Securely wipe temporary key references - guaranteed by try-finally
                if (encKey != null) {
                    SecureKeyManager.secureWipe(encKey);
                }
                if (decKey != null) {
                    SecureKeyManager.secureWipe(decKey);
                }
            }
        } catch (Exception e) {
            log.error("Error validating key lengths", e);

        } finally {
            // Wipe client challenge - guaranteed by try-finally
            if (clientChallenge != null) {
                SecureKeyManager.secureWipe(clientChallenge);
                clientChallenge = null;
            }
            closed = true;
        }
    }

    /**
     * Check if this authenticator has been closed
     *