using id in url / security issue

[eluser]Jan_1[/eluser]
Hi!
I have userprofiles, classifieds and articels
and I do use '$this->uri->segment' in controller to get the single content in the template.
So you can read the user_id in the url (..index.php/profil/23.html).

Well, I do check user-rights in the model, but shouldn't I pass an user_id more confidental? I want to protect my users data. For example using an encrypt date for 'id' instead of using autoincreatment for 'id' in mysql?

How are you doing?
Greetings, Jan