User validation from something other than forms

I'd like to make a web page which allows a user to log into the Ora Apps... everything seems to be fairly simple:

• login in as some "login" user with access to FND_USER
• Use the name and password and compare against the stuff in FND_USER

The obvious caveat though is that the password on the table is encrypted, and I don't know what Oracle uses for the encryption. Does anybody know if Oracle provides some utility to do just that kind of thing (validate a user)? I looked at the login form for Oracle Apps, and they use a user exit, which as far as I understand, is not possible to call from a standalone package. They also seem to have references back into the form (i.e. they pass field names rather than name/password).

Any ideas? Help would be very much appreciated.

Thanks,

• Roberto rdorich_at_camail2.harvard.edu