Braintree\WebhookNotification::_validateSignature PHP Method

    private static function _validateSignature($signatureString, $payload)
    {
        $signaturePairs = preg_split("/&/", $signatureString);
        $signature = self::_matchingSignature($signaturePairs);
        if (!$signature) {
            throw new Exception\InvalidSignature("no matching public key");
        }
        if (!(self::_payloadMatches($signature, $payload) || self::_payloadMatches($signature, $payload . "\n"))) {
            throw new Exception\InvalidSignature("signature does not match payload - one has been modified");
        }
    }