public function signRequest(Event $event) {
        $command = $event['command'];

        switch ($command->getName()) {
            case 'AddImage':
            case 'DeleteImage':
            case 'ReplaceMetadata':
            case 'EditMetadata':
            case 'DeleteMetadata':
            case 'GenerateShortUrl':
            case 'EditResourceGroup':
            case 'DeleteResourceGroup':
            case 'EditPublicKey':
            case 'DeletePublicKey':
            case 'AddAccessControlRules':
            case 'DeleteAccessControlRule':
                // Add the auth headers
                $this->addAuthenticationHeaders($command->getRequest());
                break;
        }
    }