public function getProtectionKey($protectionKeyId)
    {
        Validate::isString($protectionKeyId, 'protectionKeyId');

        $method = Resources::HTTP_GET;
        $path = "GetProtectionKey?ProtectionKeyId='{$protectionKeyId}'";
        $headers = [];
        $postParams = [];
        $queryParams = [];
        $statusCode = Resources::STATUS_OK;

        $response = $this->sendHttp(
            $method,
            $headers,
            $queryParams,
            $postParams,
            $path,
            $statusCode
        );

        $encoded = (string) simplexml_load_string($response->getBody());
        $encoded = implode("\n", str_split($encoded, 76));
        $encoded = "-----BEGIN CERTIFICATE-----\n".$encoded;
        $encoded .= "\n-----END CERTIFICATE-----";

        return $encoded;
    }