I want to use my key that is a BigIntegar in aes encryption

Question

Random rand = new Random();
BigInteger secretKey= new BigInteger(1024,3,rand) ;
Cipher aesCipher = Cipher.getInstance("AES");
aesCipher.init(Cipher.ENCRYPT_MODE,secretKey);

Answer 1

The two methods that i used to create the secretkey are
//that is member variables in the class server
public SecretKey secretKey;
public PublicKey publicKey;
public KeyAgreement ka ;
public static String genDhParams() {
try {
// Create the parameter generator for a 1024-bit DH key pair
AlgorithmParameterGenerator paramGen = AlgorithmParameterGenerator.getInstance("DH");
paramGen.init(1024);
// Generate the parameters
AlgorithmParameters params = paramGen.generateParameters();
DHParameterSpec dhSpec
= (DHParameterSpec)params.getParameterSpec(DHParameterSpec.class);
// Return the three values in a string
return ""+dhSpec.getP()+","+dhSpec.getG()+","+dhSpec.getL();
} catch (NoSuchAlgorithmException e) {
} catch (InvalidParameterSpecException e) {
return null;
The second method is:
private void keyExchange()throws IOException
setTextFieldEditable( true );
// Retrieve the prime, base, and private value forgenerating the key pair.
// If the values are encoded as in
// Generating a Parameter Set for the Diffie-Hellman Key Agreement Algorithm,
// the following code will extract the values
String[] values = genDhParams().split(",");
BigInteger p = new BigInteger(values[0]);
BigInteger g = new BigInteger(values[1]);
int l = Integer.parseInt(values[2]);
try {
// Use the values to generate a key pair
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DH");
DHParameterSpec dhSpec = new DHParameterSpec(p, g, l);
keyGen.initialize(dhSpec);
KeyPair keypair = keyGen.generateKeyPair();
// Get the generated public and private keys
PrivateKey privateKey = keypair.getPrivate();
publicKey = keypair.getPublic();
// Send the public key bytes to the other party..
byte[] publicKeyBytes = publicKey.getEncoded();
try // send publicKeyBytes to client
output.writeObject( publicKeyBytes );
output.flush(); // flush output to client
} // end try
catch ( IOException ioException )
displayArea.append( "\nError writing object" );
} // end catch
// Retrieve the public key bytes of the other party
try // read publicKeyBytes
publicKeyBytes = (byte[]) input.readObject(); } // end try
catch ( ClassNotFoundException classNotFoundException )
displayMessage( "\nUnknown object type received" );
} // end catch
// Convert the public key bytes into a PublicKey object
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(publicKeyBytes);
KeyFactory keyFact = KeyFactory.getInstance("DH");
publicKey = keyFact.generatePublic(x509KeySpec);
// Prepare to generate the secret key with the private key and public key of the other party
KeyAgreement ka = KeyAgreement.getInstance("DH");
ka.init(privateKey);
ka.doPhase(publicKey, true);
// Generate the secret key
secretKey = ka.generateSecret("AES");
System.out.println("the secret key is"+ secretKey);
// Use the secret key to encrypt/decrypt data;
} catch (java.security.InvalidKeyException e) {
} catch (java.security.spec.InvalidKeySpecException e) {
} catch (java.security.InvalidAlgorithmParameterException e) {
} catch (java.security.NoSuchAlgorithmException e) {
} Thanks