I was reading the Mozilla Doc about Firefox Addon Storage and it says:
Storage is a SQLite database API. It is available to trusted callers, meaning extensions and Firefox components only.
Well, it says its available to firefox only, but I managed to acess my Echofon storage by using a simple SQLite Manager for Linux. I found the .sqlite at:
/home/user/.mozilla/firefox/pmk9mj59.default/twitterfox_1.9.sqlite
The question is: how to protect my .sqlite storage in order to have it safe from external resources.