converting java to applet
 

Hai,
i am new to java. i am attaching a portion of java application which i want to convert as applet. Please help me to convert this into applet. expecting ur valuable commnets
regards
anu

<code>

import java.io.*;
import java.math.BigInteger;
import java.security.*;
import java.security.spec.*;
import java.security.interfaces.*;
import javax.crypto.*;
import javax.crypto.spec.*;
import javax.crypto.interfaces.*;
import com.sun.crypto.provider.SunJCE;

/**
* This program executes the Diffie-Hellman key agreement protocol
* between 2 parties: Alice and Bob.
*
*/

public class DHKeyAgreement2 {

private DHKeyAgreement2() {}

public static void main(String argv[]) {
try {
String mode = "USE_SKIP_DH_PARAMS";

DHKeyAgreement2 keyAgree = new DHKeyAgreement2();

if (argv.length > 1) {
keyAgree.usage();
throw new Exception("Wrong number of command options");
} else if (argv.length == 1) {
if (!(argv[0].equals("-gen"))) {
keyAgree.usage();
throw new Exception("Unrecognized flag: " + argv[0]);
}
mode = "GENERATE_DH_PARAMS";
}

keyAgree.run(mode);
} catch (Exception e) {
System.err.println("Error: " + e);
System.exit(1);
}
}

private void run(String mode) throws Exception {

DHParameterSpec dhSkipParamSpec;

if (mode.equals("GENERATE_DH_PARAMS")) {
// Some central authority creates new DH parameters
System.out.println
("Creating Diffie-Hellman parameters (takes VERY long) ...");
AlgorithmParameterGenerator paramGen
= AlgorithmParameterGenerator.getInstance("DH");
paramGen.init(512);
AlgorithmParameters params = paramGen.generateParameters();
dhSkipParamSpec = (DHParameterSpec)params.getParameterSpec
(DHParameterSpec.class);
} else {
// use some pre-generated, default DH parameters
System.out.println("Using SKIP Diffie-Hellman parameters");
dhSkipParamSpec = new DHParameterSpec(skip1024Modulus,
skip1024Base);
}

/*
* Alice creates her own DH key pair, using the DH parameters from
* above
*/
System.out.println("ALICE: Generate DH keypair ...");
KeyPairGenerator aliceKpairGen = KeyPairGenerator.getInstance("DH");
aliceKpairGen.initialize(dhSkipParamSpec);
KeyPair aliceKpair = aliceKpairGen.generateKeyPair();

// Alice creates and initializes her DH KeyAgreement object
System.out.println("ALICE: Initialization ...");
KeyAgreement aliceKeyAgree = KeyAgreement.getInstance("DH");
aliceKeyAgree.init(aliceKpair.getPrivate());

// Alice encodes her public key, and sends it over to Bob.
byte[] alicePubKeyEnc = aliceKpair.getPublic().getEncoded();

/*
* Let's turn over to Bob. Bob has received Alice's public key
* in encoded format.
* He instantiates a DH public key from the encoded key material.
*/
KeyFactory bobKeyFac = KeyFactory.getInstance("DH");
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec
(alicePubKeyEnc);
PublicKey alicePubKey = bobKeyFac.generatePublic(x509KeySpec);

/*
* Bob gets the DH parameters associated with Alice's public key.
* He must use the same parameters when he generates his own key
* pair.
*/
DHParameterSpec dhParamSpec = ((DHPublicKey)alicePubKey).getParams();

// Bob creates his own DH key pair
System.out.println("BOB: Generate DH keypair ...");
KeyPairGenerator bobKpairGen = KeyPairGenerator.getInstance("DH");
bobKpairGen.initialize(dhParamSpec);
KeyPair bobKpair = bobKpairGen.generateKeyPair();

// Bob creates and initializes his DH KeyAgreement object
System.out.println("BOB: Initialization ...");
KeyAgreement bobKeyAgree = KeyAgreement.getInstance("DH");
bobKeyAgree.init(bobKpair.getPrivate());

// Bob encodes his public key, and sends it over to Alice.
byte[] bobPubKeyEnc = bobKpair.getPublic().getEncoded();

/*
* Alice uses Bob's public key for the first (and only) phase
* of her version of the DH
* protocol.
* Before she can do so, she has to instantiate a DH public key
* from Bob's encoded key material.
*/
KeyFactory aliceKeyFac = KeyFactory.getInstance("DH");
x509KeySpec = new X509EncodedKeySpec(bobPubKeyEnc);
PublicKey bobPubKey = aliceKeyFac.generatePublic(x509KeySpec);
System.out.println("ALICE: Execute PHASE1 ...");
aliceKeyAgree.doPhase(bobPubKey, true);

/*
* Bob uses Alice's public key for the first (and only) phase
* of his version of the DH
* protocol.
*/
System.out.println("BOB: Execute PHASE1 ...");
bobKeyAgree.doPhase(alicePubKey, true);

/*
* At this stage, both Alice and Bob have completed the DH key
* agreement protocol.
* Both generate the (same) shared secret.
*/
byte[] aliceSharedSecret = aliceKeyAgree.generateSecret();
int aliceLen = aliceSharedSecret.length;

byte[] bobSharedSecret = new byte[aliceLen];
int bobLen;
try {
// show example of what happens if you
// provide an output buffer that is too short
bobLen = bobKeyAgree.generateSecret(bobSharedSecret, 1);
} catch (ShortBufferException e) {
System.out.println(e.getMessage());
}
// provide output buffer of required size
bobLen = bobKeyAgree.generateSecret(bobSharedSecret, 0);

System.out.println("Alice secret: " +
toHexString(aliceSharedSecret));
System.out.println("Bob secret: " +
toHexString(bobSharedSecret));

if (!java.util.Arrays.equals(aliceSharedSecret, bobSharedSecret))
throw new Exception("Shared secrets differ");
System.out.println("Shared secrets are the same");

}


</code>