Generating a Secret Key Using the Diffie-Hellman Key Agreement Algorithm - Java Security

Java examples for Security:Key

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Description

Generating a Secret Key Using the Diffie-Hellman Key Agreement Algorithm

Demo Code

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.KeyAgreement;
import javax.crypto.SecretKey;
import javax.crypto.spec.DHParameterSpec;

public class Main {
  public static void main(String[] args) throws Exception {

    String[] values = "this is a test".split(" ");
    BigInteger p = new BigInteger(values[0]);
    BigInteger g = new BigInteger(values[1]);
    int l = Integer.parseInt(values[2]);

    try {/*w w  w. jav  a 2s  .c om*/
      KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DH");
      DHParameterSpec dhSpec = new DHParameterSpec(p, g, l);
      keyGen.initialize(dhSpec);
      KeyPair keypair = keyGen.generateKeyPair();

      PrivateKey privateKey = keypair.getPrivate();
      PublicKey publicKey = keypair.getPublic();

      byte[] publicKeyBytes = publicKey.getEncoded();

      publicKeyBytes = null;// your key;

      X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(publicKeyBytes);
      KeyFactory keyFact = KeyFactory.getInstance("DH");
      publicKey = keyFact.generatePublic(x509KeySpec);

      KeyAgreement ka = KeyAgreement.getInstance("DH");
      ka.init(privateKey);
      ka.doPhase(publicKey, true);

      String algorithm = "DES";

      SecretKey secretKey = ka.generateSecret(algorithm);

    } catch (java.security.InvalidKeyException e) {
    } catch (java.security.spec.InvalidKeySpecException e) {
    } catch (java.security.InvalidAlgorithmParameterException e) {
    } catch (java.security.NoSuchAlgorithmException e) {
    }
  }
}

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