Apps like Viper FTP, whose purpose is to send and receive your files over a network, will send and receive your documents at your request to/from your file server, but not to Naarak Studio or any other third party. Transferred documents will be encrypted only if you use a protocol which supports encryption, such as SFTP, FTPS, HTTPS, etc., together with a correctly configured server. It is your responsibility to be aware of the security implications of the file transfer protocols you choose to use. FTP protocol is not encrypted.