think finger

[Jeremy Katz]

On Thu, 2007-10-25 at 08:55 -0400, Bryan Clark wrote:
> Pushing off from Ben's email on new user creation [1] I wanted to get 
> some setup for the think finger support that david mentioned [2].

I'd actually like to make it a teensy bit more general and think about
the non-Thinkfinger readers also.  From my Pile Of Laptops, the
Authentec readers are pretty common.  And davidz has already done some
prodding with them based on his blog ;)  

While not very relevant to the interaction, it's mostly important so
that we don't make assumptions of hardware capabilities that may or may
not be present.

> Can it's presence be detected automatically?  And it's (pam) 
> authentication be added automatically?

They're all usb devices, so pretty detectable.  Adding the pam config is
just a matter of deciding we're doing it and then adding to the stacks
written out by authconfig

> How many times does it take to train think finger support initially?

This probably depends on the hardware.  Thinkfinger is 3 swipes and
trained in hardware.  Some of the other readers just give you back an
image and you have to do verification[1] on your own.  But probably 3 is
a reasonable guess there too.  It's at least the range of "more than
one, less than many"

> Can it be (re)trained incrementally?  Is this required?

Nope, you pretty much have to do the initial readings upfront.

> Can we get the image from think finger for user feedback?  Ray mentioned 
> we might be able to fake it, which would probably be good enough.

This is definitely going to be dependent on the hardware, so probably
can't be counted on.

> Can we detect / remember the number of failed think finger attempts 
> before a successful one?  This is related to retraining, if it's 
> possible to retrain the reader or human to scan better over time.

PAM doesn't usually keep track of a number of failures.  You could have a module do it, though if you really wanted I think. 

Jeremy