Security and Authentication

public interface TransportCipher {
    /**
     * Get the key identifier for this cipher
     * @return String representing the key ID used for encryption
     * @throws GeneralSecurityException if key retrieval fails
     */
    String getKeyId() throws GeneralSecurityException;
    
    /**
     * Add encryption/decryption handlers to the Netty channel pipeline
     * @param channel - Netty Channel to add cipher handlers to
     * @throws IOException if I/O operations fail during setup
     * @throws GeneralSecurityException if cryptographic operations fail
     */
    void addToChannel(Channel channel) throws IOException, GeneralSecurityException;
}

public class CtrTransportCipher implements TransportCipher {
    /**
     * Create CTR transport cipher with specified key and initialization vector
     * @param key - Secret key for AES encryption
     * @param iv - Initialization vector for CTR mode
     * @throws GeneralSecurityException if cipher initialization fails
     */
    public CtrTransportCipher(SecretKey key, byte[] iv) throws GeneralSecurityException;
    
    @Override
    public String getKeyId() throws GeneralSecurityException;
    
    @Override
    public void addToChannel(Channel channel) throws IOException, GeneralSecurityException;
}

public class GcmTransportCipher implements TransportCipher {
    /**
     * Create GCM transport cipher with specified key
     * @param key - Secret key for AES-GCM encryption
     * @throws GeneralSecurityException if cipher initialization fails
     */
    public GcmTransportCipher(SecretKey key) throws GeneralSecurityException;
    
    @Override
    public String getKeyId() throws GeneralSecurityException;
    
    @Override
    public void addToChannel(Channel channel) throws IOException, GeneralSecurityException;
}

public class AuthClientBootstrap implements TransportClientBootstrap {
    /**
     * Create authentication client bootstrap
     * @param conf - Transport configuration containing auth settings
     * @param appId - Application identifier for authentication
     * @param secretKeyHolder - Provider for authentication secrets
     */
    public AuthClientBootstrap(TransportConf conf, String appId, SecretKeyHolder secretKeyHolder);
    
    @Override
    public void doBootstrap(TransportClient client, Channel channel) throws RuntimeException;
}

public class AuthServerBootstrap implements TransportServerBootstrap {
    /**
     * Create authentication server bootstrap
     * @param conf - Transport configuration containing auth settings
     * @param secretKeyHolder - Provider for validating authentication secrets
     */
    public AuthServerBootstrap(TransportConf conf, SecretKeyHolder secretKeyHolder);
    
    @Override
    public RpcHandler doBootstrap(Channel channel, RpcHandler rpcHandler);
}

public class SparkSaslClient implements SaslEncryptionBackend {
    /**
     * Create SASL client for authentication
     * @param secretKeyId - Identifier for the secret key
     * @param secretKey - Secret key for SASL authentication
     * @param encryptionEnabled - Whether to enable SASL encryption
     */
    public SparkSaslClient(String secretKeyId, String secretKey, boolean encryptionEnabled);
    
    /**
     * Create and configure SASL client
     * @return SaslClient configured for Spark authentication
     * @throws IOException if SASL client creation fails
     */
    public SaslClient createSaslClient() throws IOException;
    
    /**
     * Check if SASL negotiation is complete
     * @return boolean indicating if authentication is complete
     */
    public boolean isComplete();
    
    /**
     * Process a SASL challenge from the server
     * @param challenge - byte array containing the server challenge
     * @return byte array containing the client response
     * @throws IOException if challenge processing fails
     */
    public byte[] response(byte[] challenge) throws IOException;
}

public class SparkSaslServer implements SaslEncryptionBackend {
    /**
     * Create SASL server for authentication
     * @param secretKeyId - Identifier for the secret key
     * @param secretKey - Secret key for SASL authentication
     * @param encryptionEnabled - Whether to enable SASL encryption
     */
    public SparkSaslServer(String secretKeyId, String secretKey, boolean encryptionEnabled);
    
    /**
     * Create and configure SASL server
     * @return SaslServer configured for Spark authentication
     * @throws IOException if SASL server creation fails
     */
    public SaslServer createSaslServer() throws IOException;
    
    /**
     * Check if SASL negotiation is complete
     * @return boolean indicating if authentication is complete
     */
    public boolean isComplete();
    
    /**
     * Process a SASL response from the client
     * @param response - byte array containing the client response
     * @return byte array containing the server challenge
     * @throws IOException if response processing fails
     */
    public byte[] response(byte[] response) throws IOException;
}

public class SaslClientBootstrap implements TransportClientBootstrap {
    /**
     * Create SASL client bootstrap
     * @param conf - Transport configuration
     * @param appId - Application identifier
     * @param secretKeyHolder - Provider for authentication secrets
     */
    public SaslClientBootstrap(TransportConf conf, String appId, SecretKeyHolder secretKeyHolder);
    
    @Override
    public void doBootstrap(TransportClient client, Channel channel) throws RuntimeException;
}

public class SaslServerBootstrap implements TransportServerBootstrap {
    /**
     * Create SASL server bootstrap
     * @param conf - Transport configuration
     * @param secretKeyHolder - Provider for validating authentication secrets
     */
    public SaslServerBootstrap(TransportConf conf, SecretKeyHolder secretKeyHolder);
    
    @Override
    public RpcHandler doBootstrap(Channel channel, RpcHandler rpcHandler);
}

public class SaslRpcHandler extends AbstractAuthRpcHandler {
    /**
     * Create SASL RPC handler
     * @param conf - Transport configuration
     * @param channel - Netty channel for communication
     * @param delegate - Underlying RPC handler to delegate to after authentication
     * @param secretKeyHolder - Provider for authentication secrets
     */
    public SaslRpcHandler(TransportConf conf, Channel channel, RpcHandler delegate, SecretKeyHolder secretKeyHolder);
    
    @Override
    public void receive(TransportClient client, ByteBuffer message, RpcResponseCallback callback);
    
    @Override
    public StreamManager getStreamManager();
    
    @Override
    public void channelActive(TransportClient client);
    
    @Override
    public void channelInactive(TransportClient client);
}

public interface SecretKeyHolder {
    /**
     * Get the SASL user identifier for the given application
     * @param appId - Application identifier
     * @return String representing the SASL user, or null if not found
     */
    String getSaslUser(String appId);
    
    /**
     * Get the secret key for the given application
     * @param appId - Application identifier
     * @return String representing the secret key, or null if not found
     */
    String getSecretKey(String appId);
}

public class SaslMessage implements Encodable {
    /**
     * Create a SASL message
     * @param payload - byte array containing SASL data
     */
    public SaslMessage(byte[] payload);
    
    /**
     * Get the SASL payload
     * @return byte array containing the SASL data
     */
    public byte[] payload();
    
    @Override
    public int encodedLength();
    
    @Override
    public void encode(ByteBuf buf);
}

public interface SaslEncryptionBackend {
    /**
     * Encrypt data using SASL encryption
     * @param data - byte array to encrypt
     * @param offset - starting offset in the data array
     * @param len - number of bytes to encrypt
     * @return byte array containing encrypted data
     * @throws IOException if encryption fails
     */
    byte[] wrap(byte[] data, int offset, int len) throws IOException;
    
    /**
     * Decrypt data using SASL encryption
     * @param data - byte array to decrypt
     * @param offset - starting offset in the data array
     * @param len - number of bytes to decrypt
     * @return byte array containing decrypted data
     * @throws IOException if decryption fails
     */
    byte[] unwrap(byte[] data, int offset, int len) throws IOException;
    
    /**
     * Dispose of the encryption backend and clean up resources
     * @throws IOException if cleanup fails
     */
    void dispose() throws IOException;
}

public class SaslEncryption implements SaslEncryptionBackend {
    /**
     * Create SASL encryption with the specified backend
     * @param backend - SaslEncryptionBackend for actual encryption operations
     */
    public SaslEncryption(SaslEncryptionBackend backend);
    
    @Override
    public byte[] wrap(byte[] data, int offset, int len) throws IOException;
    
    @Override
    public byte[] unwrap(byte[] data, int offset, int len) throws IOException;
    
    @Override
    public void dispose() throws IOException;
}

public class SaslTimeoutException extends RuntimeException {
    /**
     * Create SASL timeout exception
     * @param message - Description of the timeout condition
     */
    public SaslTimeoutException(String message);
    
    /**
     * Create SASL timeout exception with cause
     * @param message - Description of the timeout condition
     * @param cause - Underlying cause of the timeout
     */
    public SaslTimeoutException(String message, Throwable cause);
}

import org.apache.spark.network.crypto.*;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.security.SecureRandom;

// Generate AES key for encryption
KeyGenerator keyGen = KeyGenerator.getInstance("AES");
keyGen.init(256);
SecretKey secretKey = keyGen.generateKey();

// Create CTR cipher
byte[] iv = new byte[16];
new SecureRandom().nextBytes(iv);
CtrTransportCipher ctrCipher = new CtrTransportCipher(secretKey, iv);

// Create GCM cipher
GcmTransportCipher gcmCipher = new GcmTransportCipher(secretKey);

// Apply cipher to channel
Channel channel = getNettyChannel(); // Obtain channel from transport
ctrCipher.addToChannel(channel);

System.out.println("Encryption enabled with key ID: " + ctrCipher.getKeyId());

import org.apache.spark.network.sasl.*;

// Create secret key holder
SecretKeyHolder secretKeyHolder = new SecretKeyHolder() {
    @Override
    public String getSaslUser(String appId) {
        return "spark-user-" + appId;
    }
    
    @Override
    public String getSecretKey(String appId) {
        return "secret-key-for-" + appId;
    }
};

// Client-side SASL bootstrap
SaslClientBootstrap clientBootstrap = new SaslClientBootstrap(conf, "myapp", secretKeyHolder);

// Server-side SASL bootstrap
SaslServerBootstrap serverBootstrap = new SaslServerBootstrap(conf, secretKeyHolder);

// Create authenticated transport context
List<TransportClientBootstrap> clientBootstraps = Arrays.asList(clientBootstrap);
List<TransportServerBootstrap> serverBootstraps = Arrays.asList(serverBootstrap);

TransportContext context = new TransportContext(conf, rpcHandler);
TransportClientFactory clientFactory = context.createClientFactory(clientBootstraps);
TransportServer server = context.createServer(9999, serverBootstraps);

System.out.println("SASL-authenticated server started on port: " + server.getPort());

import org.apache.spark.network.crypto.*;

// Client-side authentication
AuthClientBootstrap authClient = new AuthClientBootstrap(conf, "spark-app", secretKeyHolder);

// Server-side authentication
AuthServerBootstrap authServer = new AuthServerBootstrap(conf, secretKeyHolder);

// Create transport with authentication
TransportContext authContext = new TransportContext(conf, rpcHandler);
TransportServer authServerInstance = authContext.createServer(8443, Arrays.asList(authServer));
TransportClientFactory authClientFactory = authContext.createClientFactory(Arrays.asList(authClient));

// Connect authenticated client
TransportClient authenticatedClient = authClientFactory.createClient("localhost", 8443);
System.out.println("Authenticated client connected: " + authenticatedClient.isActive());

import java.util.concurrent.ConcurrentHashMap;
import java.util.Map;

// Custom secret key holder implementation
public class DatabaseSecretKeyHolder implements SecretKeyHolder {
    private final Map<String, String> userCache = new ConcurrentHashMap<>();
    private final Map<String, String> keyCache = new ConcurrentHashMap<>();
    
    @Override
    public String getSaslUser(String appId) {
        return userCache.computeIfAbsent(appId, id -> {
            // In real implementation, query database
            return "user-" + id;
        });
    }
    
    @Override
    public String getSecretKey(String appId) {
        return keyCache.computeIfAbsent(appId, id -> {
            // In real implementation, securely retrieve from key store
            return generateSecretKey(id);
        });
    }
    
    private String generateSecretKey(String appId) {
        // Generate or retrieve secure key for application
        return "generated-key-" + appId.hashCode();
    }
}

// Usage
SecretKeyHolder customKeyHolder = new DatabaseSecretKeyHolder();
SaslServerBootstrap customSaslServer = new SaslServerBootstrap(conf, customKeyHolder);

import org.apache.spark.network.sasl.*;

// Create SASL client and server for testing
String secretKey = "shared-secret-key";
SparkSaslClient saslClient = new SparkSaslClient("app1", secretKey, true);
SparkSaslServer saslServer = new SparkSaslServer("app1", secretKey, true);

try {
    // Perform SASL handshake
    SaslClient client = saslClient.createSaslClient();
    SaslServer server = saslServer.createSaslServer();
    
    byte[] challenge = null;
    byte[] response = client.hasInitialResponse() ? client.evaluateChallenge(new byte[0]) : null;
    
    while (!client.isComplete() || !server.isComplete()) {
        if (!server.isComplete()) {
            challenge = server.evaluateResponse(response != null ? response : new byte[0]);
        }
        if (!client.isComplete()) {
            response = client.evaluateChallenge(challenge != null ? challenge : new byte[0]);
        }
    }
    
    System.out.println("SASL handshake completed successfully");
    
    // Test encryption if enabled
    if (saslClient.isComplete() && server.getQop() != null) {
        String testData = "Hello, encrypted world!";
        byte[] encrypted = saslClient.wrap(testData.getBytes(), 0, testData.getBytes().length);
        byte[] decrypted = saslServer.unwrap(encrypted, 0, encrypted.length);
        
        System.out.println("Original: " + testData);
        System.out.println("Decrypted: " + new String(decrypted));
    }
    
} catch (Exception e) {
    System.err.println("SASL authentication failed: " + e.getMessage());
} finally {
    saslClient.dispose();
    saslServer.dispose();
}

// Complete security setup with both authentication and encryption
public TransportContext createSecureTransportContext(TransportConf conf, RpcHandler rpcHandler) throws Exception {
    // Create secret key holder
    SecretKeyHolder secretKeyHolder = new SecretKeyHolder() {
        @Override
        public String getSaslUser(String appId) {
            return System.getProperty("spark.app.user", "spark-user");
        }
        
        @Override
        public String getSecretKey(String appId) {
            return System.getProperty("spark.app.secret", "default-secret");
        }
    };
    
    // Create bootstraps for authentication and encryption
    List<TransportClientBootstrap> clientBootstraps = Arrays.asList(
        new SaslClientBootstrap(conf, "secure-app", secretKeyHolder),
        new AuthClientBootstrap(conf, "secure-app", secretKeyHolder)
    );
    
    List<TransportServerBootstrap> serverBootstraps = Arrays.asList(
        new SaslServerBootstrap(conf, secretKeyHolder),
        new AuthServerBootstrap(conf, secretKeyHolder)
    );
    
    // Create secure transport context
    TransportContext secureContext = new TransportContext(conf, rpcHandler);
    
    // Test the secure setup
    TransportServer secureServer = secureContext.createServer(0, serverBootstraps);
    TransportClientFactory secureClientFactory = secureContext.createClientFactory(clientBootstraps);
    
    System.out.println("Secure transport context created successfully");
    System.out.println("Server port: " + secureServer.getPort());
    
    return secureContext;
}

// Custom RPC handler with authentication error handling
public class SecureRpcHandler extends RpcHandler {
    private final RpcHandler delegate;
    private final Set<String> authenticatedClients = ConcurrentHashMap.newKeySet();
    
    public SecureRpcHandler(RpcHandler delegate) {
        this.delegate = delegate;
    }
    
    @Override
    public void receive(TransportClient client, ByteBuffer message, RpcResponseCallback callback) {
        String clientId = client.getSocketAddress().toString();
        
        if (!authenticatedClients.contains(clientId)) {
            callback.onFailure(new SecurityException("Client not authenticated: " + clientId));
            return;
        }
        
        delegate.receive(client, message, callback);
    }
    
    @Override
    public StreamManager getStreamManager() {
        return delegate.getStreamManager();
    }
    
    @Override
    public void channelActive(TransportClient client) {
        // Mark client as authenticated after successful bootstrap
        String clientId = client.getSocketAddress().toString();
        authenticatedClients.add(clientId);
        System.out.println("Client authenticated: " + clientId);
        delegate.channelActive(client);
    }
    
    @Override
    public void channelInactive(TransportClient client) {
        String clientId = client.getSocketAddress().toString();
        authenticatedClients.remove(clientId);
        System.out.println("Client disconnected: " + clientId);
        delegate.channelInactive(client);
    }
    
    @Override
    public void exceptionCaught(Throwable cause, TransportClient client) {
        if (cause instanceof SaslTimeoutException) {
            System.err.println("SASL authentication timeout for client: " + client.getSocketAddress());
        } else if (cause instanceof SecurityException) {
            System.err.println("Security exception for client: " + client.getSocketAddress() + " - " + cause.getMessage());
        }
        delegate.exceptionCaught(cause, client);
    }
}

public class AuthMessage implements Encodable {
    public static class Challenge extends AuthMessage {
        public Challenge(byte[] challenge);
        public byte[] challenge();
    }
    
    public static class Response extends AuthMessage {
        public Response(byte[] response);
        public byte[] response();
    }
    
    public static class Success extends AuthMessage {
        public Success(byte[] payload);
        public byte[] payload();
    }
}

public abstract class AbstractAuthRpcHandler extends RpcHandler {
    protected final TransportConf conf;
    protected final Channel channel;
    protected final RpcHandler delegate;
    
    protected AbstractAuthRpcHandler(TransportConf conf, Channel channel, RpcHandler delegate);
    
    protected abstract boolean isAuthenticated();
    protected abstract void doAuthenticationHandshake(TransportClient client, ByteBuffer message, RpcResponseCallback callback);
}