Authentication/Access-control libraries

["n30" <n30_lists () hotmail com>]

Gurus,

Say I am a programmer designing an ecommerce site & wanting to write secure
code. I have heard there are commercial & opensource secure libraries
available out there that i can reuse for performing authentication and
access control.

Any links/pointers to them??

I am specifically looking for asp & java. But any language should be fine. I
will get an insight into things.

Thanks in advance
-n