Protecting files in linux

[Jorge Delgado]

Hi, i would like to protect files like passwords and websites of Firefox
(iceweasel), and this cannot be done encripting the files. 

So, i need some program for protect the files and, at the same time be
using them. If i encript the files, i cannot use them at the same time.
And if I cannot use them at the same time, it's meaningless.

Somebody could help me? Thank you very much, I appreciatte your help.