code: private function isCorrectSign($sign, $requestParams)
  	{
  		ksort($requestParams);
  		$signData = implode('|', $requestParams);
  		$key = self::getConfig('provider.key');
  		$localSign = base64_encode(hash_hmac('sha1', $signData, $key));
  
  		return $sign == $localSign;
  
  	}
docs: Проверка подписи из callback`а
  
  @param string $sign
  @param array  $requestParams
  
  @return bool