public function validate_webhook($params) {

    $sig = $params['signature'];
    unset($params['signature']);

    if ( ! isset($sig)) {
      return false;
    }

    $data = array(
      'data'      => $params,
      'secret'    => $this->account_details['app_secret'],
      'signature' => $sig
    );

    return $this->validate_signature($data);

  }