import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.util.Random ;
import javax.swing.*;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SignatureException;
import java.util.Formatter;

class FindHash {

private static final String HMAC_SHA1_ALGORITHM = "HmacSHA1";

public FindHash() {
try {
String inputMessage=JOptionPane.showInputDialog(null,"Enter message to hash");
String hmac_message = calculateRFC2104HMAC(inputMessage, "key1");
JOptionPane.showMessageDialog(null,"Hash of the message: "+hmac_message);
}
catch(Exception e) {
System.out.println(e);
}
}

//************* Coding for Hashing *******************

private static String toHexString(byte[] bytes)
{
Formatter formatter = new Formatter();
for (byte b : bytes)
{
formatter.format("%02x", b);

}
return formatter.toString();
}

public static String calculateRFC2104HMAC(String data, String key) throws SignatureException, NoSuchAlgorithmException, InvalidKeyException
{
SecretKeySpec signingKey = new SecretKeySpec(key.getBytes(), HMAC_SHA1_ALGORITHM);
Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);
mac.init(signingKey);
return toHexString(mac.doFinal(data.getBytes()));
}

public static void main(String args[]) {
FindHash fh = new FindHash();
}

}