protected function _post($data) {
		$ch = curl_init();
		curl_setopt_array($ch, array(
			CURLOPT_URL            => static::ENDPOINT,
			CURLOPT_POST           => true,
			CURLOPT_POSTFIELDS     => json_encode($data),
			CURLOPT_HEADER         => false,
			CURLOPT_RETURNTRANSFER => true,
			CURLOPT_SSL_VERIFYPEER => true,
			CURLOPT_SSL_VERIFYHOST => 2,
			CURLOPT_FOLLOWLOCATION => false,
			CURLOPT_HTTPHEADER => array('Content-Type: application/json')
		));

		$response = curl_exec($ch);
		curl_close($ch);

		if ($response === false) {
			throw new Exception('Failed to contact BrowserID verification service');
		}

		$decodedResponse = json_decode($response);
		if (!$decodedResponse) {
			throw new Exception('Response is not valid JSON');
		}

		return $decodedResponse;
	}