code: public OpenPgpMessage decryptOpenPgpElement(OpenPgpElement element, OpenPgpContact sender)
              throws SmackException.NotLoggedInException, IOException, PGPException {
          return provider.decryptAndOrVerify(element, getOpenPgpSelf(), sender);
      }
docs: Decrypt and or verify an {@link OpenPgpElement} and return the decrypted {@link OpenPgpMessage}.
  
  @param element {@link OpenPgpElement} containing the message.
  @param sender {@link OpenPgpContact} who sent the message.
  
  @return decrypted and/or verified message
  
  @throws SmackException.NotLoggedInException in case we aren't logged in (we need to know our jid)
  @throws IOException IO error (reading keys, streams etc)
  @throws PGPException in case of an PGP error