Suggestions for an authentication library

[eluser]vivekh[/eluser]
Hello everyone,

Newbie here. I am about to start start writing an app using CodeIgniter and Extjs. I first thought of creating everything from scratch but found that many libraries exist which I can use in my app.

So I searched for an Authentication library which would help me with the login, registration & authentication process. Most of libraries I found were for use with forums with users like moderators and administrators.

I have 3 types of users. Lets say a Buyer, a Seller and the admin who looks over everything. If anyone could suggest me a suitable existing library which I can use for my app then it is highly appreciated.

Pardon my ignorance if no such libraries exist :-)

Thanks in advance.

[eluser]Vheissu[/eluser]
If you want something that uses groups by the sounds of it you do, look up IonAuth, it's what you want. My auth library isn't group based, it's role based instead.

[eluser]JonoB[/eluser]
[quote author="Vheissu" date="1303148704"]If you want something that uses groups by the sounds of it you do, look up IonAuth, it's what you want. My auth library isn't group based, it's role based instead.[/quote]
Can you explain what the different is between role based and group based please?

[eluser]vivekh[/eluser]
[quote author="JonoB" date="1303226223"]
Can you explain what the different is between role based and group based please?[/quote]

According to what I have understood a role based is one which most forums use. They have users like moderators, super moderators and administrators. A normal user could be promoted to these roles as well as demoted.

A group based is one which has only a certain type of users with no features as promotion and demotion.

I guess this is what it means.