Silicon.com: Passports replaced by iris scanning in Amsterdam

[Ken Brown]

Charles Lindsey wrote:
> 
>         On Tue, 30 Oct 2001 13:02:12 +0100
>         Arturo Quirantes <aquiran@ugr.es> said...
> 
> >         Bruce Scnheier wrote something about the
> > increase-security-at-any-costs recently.  He said, suppose that one
> > person in 10.000.000 is a terrorist, and that marvel machine X (in
> > his example, face-recognition tech) has a 99.9% success rate. What
> > does it mean?  That there4ll be 10.000 false positives (innocent
> > people mistaken by terrorist) for every true one (the bad guy being
> > caught).  At the end, the security guard will just get tired of the
> > machine beeping and will let false -and true- positives thru.

> No that is wrong. You are supposing that all 10,000,000 are going to
> have their faces inspected by the security guard. But in fact, the test
> will only be applied to a group of people who are likely to contain more
> terrorists than the 1 in 10,000,000. 
 
That's arse-about-face.  The point of automatic scanning has to be to
filter the data before human intervention. Otherwise why bother?  

> For example, those under direct
> suspicion

Who would be being watched by something more intelligent than an iris
scanner I hope. And how is the scanner meant to know they are  under
direct suspicion before it has, as it were, scanned them?

> or those entering secure buildings, or attempting to board
> aircraft.
> If we suppose that only 1 in 100 of the general population has occasion
> to enter secure buildings etc during the course of one year, then that
> is 100 false positives, which is acceptable.

Also I don't see how you  can assume that the proportion of terrorists
on board planes is so much  higher than that anywhere else.

If someone knows how to pre-sort the entire population of Europe so that
one group is 100 times more likely to contain terrorists than the other
then they ought to be doing it & not wasting their time with iris
scanners!

Ken Brown