This CLI program is designed to hide files in Rars. Hidden files aren't removed, but they won't appear in winrar and won't be descompressed. You can reveal these files later with the program.
I developed this program in 2013, and his code quality is pretty bad (long functions, spanish names...). At least there are a lot of comments (in spanish), and the most important... It works!.
I am not longer maintaining this program, but you can learn the algorithm and apply it. Be my guest.