private void test() throws Exception {
  KeyPair keyPair=null;
  keyPair=readPkcs1(new FileInputStream("/somefolder/private.pem"));
  Signature signature=Signature.getInstance("SHA256withRSA");
  signature.initSign(keyPair.getPrivate());
  signature.update(yourRequest.getBytes());
  byte[] signatureBytes=signature.sign();
  keyPair=readPkcs8(new FileInputStream("/somefolder/private.pk8der"));
  signature.initVerify(keyPair.getPublic());
  signature.update(yourReqeust.getBytes());
  System.out.println(signature.verify(signatureBytes));
}