public function verify(SignedRequest $request)
    {
        $payload = $this->buildPayloadFromRequest($request);

        $calculatedSignature = \hash_hmac(self::HMAC_HASH_ALGO, $payload, $this->signingKey, true);
        $expectedSignature = \base64_decode($request->signature, true);

        return \hash_equals($expectedSignature, $calculatedSignature);
    }