JGSS API

import org.ietf.jgss.*;

public class GSSExample {
    public static void main(String[] args) throws GSSException {
        // Get the default GSSManager instance
        GSSManager manager = GSSManager.getInstance();
        
        // Kerberos v5 mechanism OID
        Oid krb5Mechanism = new Oid("1.2.840.113554.1.2.2");
        Oid krb5PrincipalNameType = new Oid("1.2.840.113554.1.2.2.1");
        
        // Create a name for the client
        GSSName clientName = manager.createName("user@REALM", 
                                               GSSName.NT_USER_NAME);
        
        // Create a name for the server
        GSSName serverName = manager.createName("service/host@REALM",
                                               krb5PrincipalNameType);
    }
}

import org.ietf.jgss.*;

public class GSSClient {
    public static void establishContext(GSSContext context) 
            throws GSSException {
        byte[] inToken = new byte[0];
        byte[] outToken;
        
        // Context establishment loop
        while (!context.isEstablished()) {
            // Generate token for server
            outToken = context.initSecContext(inToken, 0, inToken.length);
            
            if (outToken != null) {
                sendTokenToServer(outToken);
            }
            
            if (!context.isEstablished()) {
                inToken = receiveTokenFromServer();
            }
        }
        
        // Context is now established
        System.out.println("Context established!");
        System.out.println("Initiator: " + context.getSrcName());
        System.out.println("Acceptor: " + context.getTargName());
        System.out.println("Lifetime: " + context.getLifetime() + " seconds");
    }
    
    private static void sendTokenToServer(byte[] token) {
        // Send token to server via network
    }
    
    private static byte[] receiveTokenFromServer() {
        // Receive token from server via network
        return new byte[0];
    }
}

import org.ietf.jgss.*;

public class KerberosClient {
    public static void main(String[] args) {
        try {
            GSSManager manager = GSSManager.getInstance();
            
            // Create server name (service/host@REALM)
            GSSName serverName = manager.createName(
                "service/[email protected]",
                GSSName.NT_HOSTBASED_SERVICE
            );
            
            // Acquire client credentials
            GSSCredential clientCred = manager.createCredential(
                null,
                GSSCredential.DEFAULT_LIFETIME,
                new Oid("1.2.840.113554.1.2.2"),
                GSSCredential.INITIATE_ONLY
            );
            
            // Create context
            GSSContext context = manager.createContext(
                serverName,
                new Oid("1.2.840.113554.1.2.2"),
                clientCred,
                GSSContext.DEFAULT_LIFETIME
            );
            
            // Request services
            context.requestMutualAuth(true);
            context.requestConf(true);
            context.requestInteg(true);
            
            // Establish context
            byte[] token = context.initSecContext(new byte[0], 0, 0);
            // ... exchange tokens with server ...
            
            // Send encrypted message
            String message = "Hello, secure world!";
            MessageProp msgProp = new MessageProp(0, true);
            byte[] secureMsg = context.wrap(
                message.getBytes(),
                0,
                message.length(),
                msgProp
            );
            
            // Clean up
            context.dispose();
            
        } catch (GSSException e) {
            System.err.println("GSS Error: " + e.getMessage());
            e.printStackTrace();
        }
    }
}