private function verify(RequestInterface $httpRequest)
    {
        $extensions = array('crt', 'pem', 'cer', 'der');
        $caDir = __DIR__ . '/../CA/';

        // Must be https
        $url = $httpRequest->getUrl();
        if (substr($url, 0, 5) != 'https') {
            $httpRequest->getConfig()->set('verify', false);
            return;
        }

        // Default
        $httpRequest->getConfig()->set('verify', $caDir . 'curl-ca-bundle.crt');

        // Look for a host specific CA file
        $host = strtolower(parse_url($url, PHP_URL_HOST));
        if (!$host)
            return;

        $filename = $host;
        do {
            // Look for the possible extensions
            foreach ($extensions as $ext)
                if (file_exists($verify = $caDir . $filename . '.' . $ext)) {
                    $httpRequest->getConfig()->set('verify', $verify);
                    return;
                }

            // Remove a subdomain each time
            $filename = substr($filename, strpos($filename, '.') + 1);
        } while (substr_count($filename, '.') > 0);

        // No specific match
        return;
    }