Security of configuration file.

[jridky]

Try to think about how to protect data in configuration file from abuse. In configuration file will be (probably) saved even unique id of client, so data stored in the file should not be in plain text, but somehow encoded or encrypted. Find out how is saving of sensitive data solved in fedora.

[SimonMatej]

By encryption part of fedora documentation, GnuPG is used for file based encryption (https://www.gnupg.org/). GnuPG is designed to be used interactively, and not as an API, but there is a library GnuPG Made Easy (GPGME), which should work for us.
Another way is using CryptoAPI from linux kernel.