public static function verifyShopifyRequest()
    {
        $data = $_GET;

        if(!isset(ShopifySDK::$config['SharedSecret'])) {
            throw new SdkException("Please provide SharedSecret while configuring the SDK client.");
        }

        $sharedSecret = ShopifySDK::$config['SharedSecret'];

        //Get the hmac and remove it from array
        if (isset($data['hmac'])) {
            $hmac = $data['hmac'];
            unset($data['hmac']);
        } else {
            throw new SdkException("HMAC value not found in url parameters.");
        }
        //signature validation is deprecated
        if (isset($data['signature'])) {
            unset($data['signature']);
        }
        //Create data string for the remaining url parameters
        $dataString = http_build_query($data);

        $realHmac = hash_hmac('sha256', $dataString, $sharedSecret);

        //hash the values before comparing (to prevent time attack)
        if(md5($realHmac) === md5($hmac)) {
            return true;
        } else {
            return false;
        }
    }