Easily extensible auth library

[eluser]jpi[/eluser]

but aren’t there quite some interfaces and other classes from Zend that are being used?

Not really, just Zend_DB in one or two method of Zend_Auth_Adapter_DbTable and Zend_Session in Zend_Auth_Storage_Session.

Before writing your own Auth lib from scratch, dive a bit into Zend_Auth code, i really think it is worth.