The problem is that I need to share files between 2 programs, but I don't want that those files are accessible by the user of the computer and other programs than these 2. So the flow of the files are like this: Program A (which I will code myself) recieves a file from the internet and puts somewhere on the computer. Then Program A calls Program B (which I didn't code and can't change). Program B reads the downloaded file and does some things with it and produces another file which Program B puts also somewhere on the computer. Then Program A reads that file and uploads it to the internet.
What I have found I thought that maybe Windows Sandbox was interesting, but the problem with Windows Sandbox is that it's only available to windows 10 pro and windows 11, and that it is virtualised, and performance is quite important for Program B... So any virtualised software is not very usable, unless it is close to native performance.
For Linux, I found FreeBSD jails. But this seems more focussed on keeping the applications in the jail prohibited to access files outside the jail than to prohibit the programs outside the jail from reading and writing to files in the jail. So actually I need the opposite...
Another interesting concept was to keep the files stored in RAM like mmap in Linux, but since I can't change Program B, I don't know how to implement that. Is there some kind of container application that encapsulates the IO of Program B and redirects it to a file in RAM?
Does anyone have some suggestions? Thanks!
You can't really prevent the user/owner of the computer from reading the file if you are storing it on their disk. You can try to make it more difficult to access the content (which is what DRM does) but ultimately you the user can always bypass your controls given sufficient motivation and resources. Even if you store the files purely in RAM, a user with administrative permissions can dump your program's memory, and extract the files from there.