private function createSignatureHash(Signature $signature)
    {
        $length = $this->getSignatureLength();

        return pack(
            'H*',
            sprintf(
                '%s%s',
                str_pad($this->adapter->decHex($signature->getR()), $length, '0', STR_PAD_LEFT),
                str_pad($this->adapter->decHex($signature->getS()), $length, '0', STR_PAD_LEFT)
            )
        );
    }