I think SSL might help you out over here. You can check out the JSSE
docs for more info.

Hope this helps.

Here is an SSL Tunnel that I wrote to use anon SSL (you may want
utilize an SSL context with real certs {you can gen self certs with
keytool})

<<SocketConnector.java>>
import java.net.InetAddress;
import java.net.Socket;
import java.util.Arrays;

class SocketConnector implements Runnable {
 Socket input = null;
 Socket output = null;
 String desc = null;
 boolean sniff = false;

 SocketConnector(Socket input, Socket output, String desc, boolean
sniff) {
   this.sniff = sniff;
   this.desc = desc;
   this.input = input;
   this.output = output;
 }

 public void run() {
   try {
     int i = 0;
     byte[] b = new byte[1024];
     while ((i = input.getInputStream().read(b)) > 0) {
       if (sniff) {
         String str1 = desc + ":";
         String str2 = "";
         for (int j = 0; j < i; j++) {
           String hex = Integer.toHexString(b[j]&0xFF);
           str1 += " " + (hex.length()==1?"0"+hex:hex);
           str2 += (char)((b[j]>='
'&&b[j]<='~')||(b[j]>=160&&b[j]<=255)?b[j]:'.');
           if ((1+j) % 16 == 0) {
             System.out.println(str1 + "   " + str2);
             char[] c = new char[desc.length()+1];
             Arrays.fill(c, ' ');
             str1 = new String(c);
             str2 = "";
           }
         }
         if (i%16!=0) {
           char[] c = new char[3*(16-(i%16))];
           Arrays.fill(c, ' ');
           System.out.println(str1 + new String(c) + "   " + str2);
         }
       }
       output.getOutputStream().write(b, 0, i);
     }
   } catch (Exception e) {
     System.out.println(desc + ":Input Closed");
   }
 }
}

<<TunnelServer.java>>
import javax.net.ssl.SSLServerSocket;
import javax.net.ssl.SSLServerSocketFactory;
import javax.net.ssl.SSLSocket;
import java.net.Socket;

class TunnelServer {
 // (1) server(SSL) for localhost:port ssl tunnel
 // (2) client to localhost:port actual service
 static public void main(String[] args) throws Exception {
   if (args.length < 3) {
     System.err.println("Usage TunnelServer port remoteHost
remotePort");
     return;
   }

   int port = Integer.parseInt( args[0] );
   String remoteHost = args[1];
   int remotePort = Integer.parseInt( args[2] );
   boolean sniff = Boolean.valueOf(args[3]).booleanValue();

   System.out.println("Press Ctrl-C to exit");

   SSLServerSocket listen
     = (SSLServerSocket)SSLServerSocketFactory.getDefault().createServerSocket(
         port );
   listen.setEnabledCipherSuites( new String[]
{"SSL_DH_anon_WITH_RC4_128_MD5"} );
   
   while (true) {
     SSLSocket sslClient = (SSLSocket)listen.accept();
     sslClient.setEnabledCipherSuites( new String[]
{"SSL_DH_anon_WITH_RC4_128_MD5"} );
     System.out.println("Received connect from " +
sslClient.getInetAddress().getHostName());

     Socket localClient = new Socket(remoteHost, remotePort );

     new Thread(new SocketConnector(sslClient, localClient,
"rsp-rdr",sniff)).start();
     new Thread(new SocketConnector(localClient, sslClient,
"msg-act",sniff)).start();
   }
 }
}

<<TunnelClient.java>>
import javax.net.ssl.SSLSocket;
import java.net.Socket;
import java.net.InetAddress;
import javax.net.ssl.SSLSocketFactory;
import java.net.ServerSocket;

class TunnelClient {
 private static final int BYTES_TO_EAT = 2;
 private static final int WAIT_EAT = 1000;
 private static final int RESOLUTION = 10;

 static SSLSocket createSocket(String host, int port) throws
Exception {
   Socket s = new Socket(InetAddress.getByName(host), port);

   int slept = 0;
   outer: for (int i = 0; i < BYTES_TO_EAT; i++) {
     while (true) {
       int a = s.getInputStream().available();
       if (a>0) {
         break;
       } else if (slept>WAIT_EAT) {
         break outer;
       } else {
         try {
           Thread.sleep(RESOLUTION);
           slept += RESOLUTION;
        } catch (InterruptedException e) {
        }
      }
     }
     int b1 = s.getInputStream().read();
   }
   
   return (SSLSocket)((SSLSocketFactory)SSLSocketFactory.getDefault()).createSocket(
     s, host, port, true);
 }

 // (1) server for localhost:port actual service
 // (2) client(SSL) to remotehost:port ssl tunnel
 static public void main(String[] args) throws Exception {
   if (args.length < 3) {
     System.err.println("Usage TunnelClient port remoteHost
remotePort");
     return;
   }

   int port = Integer.parseInt( args[0] );
   String remoteHost = args[1];
   int remotePort = Integer.parseInt( args[2] );
   boolean sniff = Boolean.valueOf(args[3]).booleanValue();

   System.out.println("Press Ctrl-C to exit");

   ServerSocket listen = new ServerSocket ( port );
   while (true) {
     Socket localClient = listen.accept();
     System.out.println("Received connect from " +
localClient.getInetAddress().getHostName());

     SSLSocket sslClient = createSocket(remoteHost, remotePort);
     sslClient.setEnabledCipherSuites( new String[]
{"SSL_DH_anon_WITH_RC4_128_MD5"} );

     new Thread(new SocketConnector(sslClient, localClient,
"msg-rdr",sniff)).start();
     new Thread(new SocketConnector(localClient, sslClient,
"rsp-act",sniff)).start();
   }
 }
}