src/FintechFab/QiwiSdk/Gateway.php
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;

	}
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;

	}
Проверка подписи из callback`а

@param string $sign
@param array  $requestParams

@return bool