package org.example.dataflow;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.io.Serializable;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;

public class Crypto implements Serializable {

    private static final String TAG = "Crypto";

    transient private Mac hmacSHA256;

    public Crypto() {
       init();
    }

    public void init() {
        try {
            hmacSHA256 = Mac.getInstance("HmacSHA256");
        } catch (SecurityException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
    }

    public byte[] calculateHmacSHA256(byte[] input, byte[] key) {
        byte[] output = null;
        try {
            if(hmacSHA256 == null) {
                init();
            }
            hmacSHA256.init(new SecretKeySpec(key, "HmacSHA256"));
            output = hmacSHA256.doFinal(input);
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        }
        return output;
    }
}