code: package crypto;
  import java.security.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.util.Arrays;
  
  
  public class DigestMethod {
      private final static org.apache.log4j.Logger logger = org.apache.log4j.Logger.getLogger(DigestMethod.class);
  
      static public byte[] hash(byte[] toHash) {
          MessageDigest digestMethod = null;
          try {
              digestMethod = MessageDigest.getInstance("SHA-256");
          } catch (NoSuchAlgorithmException e) {
              logger.fatal("", e);
          }
          assert digestMethod != null;
          return digestMethod.digest(toHash);
      }
  
      static public boolean validate(byte[] d1, byte[] d2) {
          return Arrays.equals(d1, d2);
      }
  }
  