Re: Face recognition in GDM ...

[Bob Doolittle <Robert Doolittle Sun COM>]

José Miguel Buenaposada Biencinto wrote:

> Thanks a lot for your advise, I'm only a long time GNU/Linux user and not
> really known very much how to program specifically for Linux.
>
> I'm thinking in giving the posibility to the user (and to debug the 
> vision
> algorithms) of seeing the captured video stream in a window with the
> detected/recognized faces highlighted. In this case I supouse we have to
> modify the GDM user interface, haven't we?


I don't see why.  You should be able to pop up a window directly from
the PAM module.  That way, again, your code would be independent of
GDM, and could work with screen-lock programs as well, which I would
think would be important in any real-world scenario.

PAM is for authentication, and is (or should be) used by any app that
needs to authenticate.  Biometrics like face recognition is a type of
authentication, that you'd potentially want to use in a number of
different contexts.  Use the authentication framework, not this
specific application (GDM) and you'll get more value out of your
solution.  Not to mention it being easier to develop if it's
independent.  Applications like GDM should *not* do authentication
directly, because that makes the solution less portable/useful.  PAM
is structured, modular, and designed just for this purpose.  People
have used it to create quite interesting authentication solutions
based on things like Kerberos, and an admin can mix/match whatever
authentication methods s/he likes for different applications.

Teach your students the value of software modularity, and don't
embed a useful technology in a particular monolithic piece of
software if you don't need to.  We may love gdm, but this isn't
the place to put something like you are proposing, for lots of
reasons.

Regards,
  Bob

> How do you think is the
> best way (in the sense of minimum number of changes) of modify the
> GDM user interface?
>
> Thanks a lot for your help. You have been quite helpfull.
> Jose M. Buenaposada.
>
> Bob Doolittle wrote:
>
> > Hi Jose,
> >
> > Just a note that the right way to do any kind of
> > biometric authentication is through the use of the
> > Pluggable Authentication Module framework (PAM).
> > GDM will work with PAM, by calling
> > pam_authenticate().  You can write a PAM module
> > that implements pam_sm_authenticate(), and put
> > whatever fun stuff you want into it, and then
> > create a PAM stack in pam.conf that either uses
> > this module in isolation for gdm or combine it
> > with a module that acquires a password or uses
> > a smartcard or does something else useful.
> >
> > Do not consider modifying GDM code directly
> > for this purpose, a PAM module would be much
> > more generally useful (for instance it could be used
> > to unlock a screen-lock program as well as log in).
> >
> > It's easier to test, too.  You can write a very simple
> > PAM client that calls pam_authenticate and debug
> > your code outside of the GDM framework, then
> > drop it in by configuring pam.conf when it's ready.
> >
> > Regards,
> >   Bob
> >
> > José Miguel Buenaposada Biencinto wrote:
> >
> > > Hi to all GDM developers,
> > >
> > > I'm a researcher in Computer Vision and I'd like to add some sort of 
> > > face recognition
> > > sytem to the Linux login. The idea is to use real-time face 
> > > recognition throught a video
> > > camera to select the right user's name from a little database 
> > > containing an image of
> > > each user. The user, of course, will have to type the password but 
> > > not the login name
> > > (for extra security). I'm thinking in implementing one of the state 
> > > of the art face detectors
> > > and face recognition algorithms (as it will not be the main user's 
> > > identification method,
> > > as the passwd will remain in place, it has not to be very 
> > > sofisticated).
> > >
> > > The idea is to be developed within a master thesis of one of our 
> > > students. What
> > > I'd like to know, before even look for a student to do it, is what 
> > > do you think
> > > (GDM developer) will be the best way to modify the GDM code?, the 
> > > place in the
> > > code to loook for? what to modify with the minimum impact in 
> > > stability? What version
> > > of the code is best to start? And what ever do you think will be 
> > > interesting ...
> > > I have not even taken a look into the GDM code yet.
> > >
> > > I think it will be very cool to have such a thing as face recogtion 
> > > in the linux login
> > >
> > > Best regards.
> > > JM.
> >
> >
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