SignatureVerification.java

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.Signature;
import java.util.Scanner;
public class SignatureVerification {
 public static void main(String args[]) throws Exception{
 //Creating KeyPair generator object
 KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("DSA");

 //Initializing the key pair generator
 keyPairGen.initialize(2048);

 //Generate the pair of keys
 KeyPair pair = keyPairGen.generateKeyPair();

 //Getting the privatekey from the key pair
 PrivateKey privKey = pair.getPrivate();
 //Creating a Signature object
 Signature sign = Signature.getInstance("SHA256withDSA");
 //Initializing the signature
 sign.initSign(privKey);
 byte[] bytes = "Hello how are you".getBytes();

 //Adding data to the signature
 sign.update(bytes);

 //Calculating the signature
 byte[] signature = sign.sign();

 //Initializing the signature
 sign.initVerify(pair.getPublic());
 sign.update(bytes);

 //Verifying the signature
 boolean bool = sign.verify(signature);

 if(bool) {
 System.out.println("Signature verified");
 } else {
 System.out.println("Signature failed");
 }
 }
}