public function signRequestUrl(
		$requestUrl = '',
		$resourceType = Storage::RESOURCE_UNKNOWN,
		$requiredPermission = CredentialsAbstract::PERMISSION_READ
	) {
	    // Look for a matching permission
	    foreach ($this->getPermissionSet() as $permittedUrl) {
	        if ($this->permissionMatchesRequest($permittedUrl, $requestUrl, $resourceType, $requiredPermission)) {
	            // This matches, append signature data
	            $parsedPermittedUrl = parse_url($permittedUrl);

	            if (strpos($requestUrl, '?') === false) {
	                $requestUrl .= '?';
	            } else {
	                $requestUrl .= '&';
	            }

	            $requestUrl .= $parsedPermittedUrl['query'];

	            // Return url
	            return $requestUrl;
	        }
	    }

	    // Return url, will be unsigned...
	    return $requestUrl;
	}