How to secure paypal signature, username and password stored in app_config

Hi
   I store paypal api username, password and signature as simple text in
config/app_config.yml. I would like to know whether this can be
protected , than just storing it as text which anybody can read from
app_config.yml.

Thanks
Tom

Hi
   I am using app_config.yml exactly like
http://railscasts.com/episodes/143-paypal-security
       Please help

Thanks

If you plan on encrypting it, you’ll need to store the encryption key somewhere. Someone who has access to your app_config.yml file would probably also have access to wherever you stored the encryption key.

So you probably could encrypt it, but it wouldn’t really be solving anything.

Why not just worry about not letting those who shouldn’t see the username and password have access to view app_config.yml?