Linux: where can I store data secretly in order to implement a time-limited demo?

Question

I'm writing a Linux app that has a time limited demo. There's not going to be a server that the app can phone home to, so I need to store data on the system in order to figure out if the demo has been started and how much time is remaining. The location of this data needs to be obfuscated so that a non-power user is unlikely to be able to find it, even though I'm aware Linux users tend to skew more towards power users than for other operating systems.

I already know the logistics of how to implement a time limited demo as long as I can store data secretly somewhere on the system, but I'm not sure how to do that last part. The requirements here are:

• The data needs to be globally readable and writable so that any user account can access it and modify it (as the demo applies system-wide and not on a per-user basis)

• Wherever the data is stored or whichever method I use needs to be available in RHEL, Fedora and Debian based distributions. Even better if it's basically guaranteed to be available in all distros.

Is there any way to accomplish this?

Answer 1

Well after doing quite a bit more research I've concluded that the only place to put that kind of data is /var/tmp. Not exactly secret or obfuscated, but there's no other place in the filesystem that's globally writable and isn't cleared out after rebooting the system.