At 6:23 AM -0600 2/15/05, Bruce Schneier wrote:

TSA's Secure Flight

As I wrote last month, I am participating in a working group to study the security and privacy of Secure Flight, the U.S. government's program to match airline passengers with a terrorist watch list. In the end, I signed the NDA allowing me access to SSI (Sensitive Security Information) documents, but managed to avoid filling out the paperwork for a SECRET security clearance.

Last month the group had its second meeting.

At this point, I have four general conclusions. One, assuming that we need to implement a program of matching airline passengers with names on terrorism watch lists, Secure Flight is a major improvement -- in almost every way -- over what is currently in place. (And by this I mean the matching program, not any potential uses of commercial or other third-party data.)

Two, the security system surrounding Secure Flight is riddled with security holes. There are security problems with false IDs, ID verification, the ability to fly on someone else's ticket, airline procedures, etc. There are so many ways for a terrorist to get around the system that it doesn't provide much security.

Three, the urge to use this system for other things will be irresistible. It's just too easy to say: "As long as you've got this system that watches out for terrorists, how about also looking for this list of drug dealers...and by the way, we've got the Super Bowl to worry about too." Once Secure Flight gets built, all it'll take is a new law and we'll have a nationwide security checkpoint system.

And four, a program of matching airline passengers with names on terrorism watch lists is not making us appreciably safer, and is a lousy way to spend our security dollars.

Unfortunately, Congress has mandated that Secure Flight be implemented, so it is unlikely that the program will be killed. And analyzing the effectiveness of the program in general, potential mission creep, and whether the general idea is a worthwhile one, is beyond the scope of the working group. In other words, my first conclusion is basically all that they're interested in hearing.

But that means I can write about everything else.

To speak to my fourth conclusion: Imagine for a minute that Secure Flight is perfect. That is, we can ensure that no one can fly under a false identity, that the watch lists have perfect identity information, and that Secure Flight can perfectly determine if a passenger is on the watch list: no false positives and no false negatives. Even if we could do all that, Secure Flight wouldn't be worth it.

Secure Flight is a passive system. It waits for the bad guys to buy an airplane ticket and try to board. If the bad guys don't fly, it's a waste of money. If the bad guys try to blow up shopping malls instead of airplanes, it's a waste of money.

If I had some millions of dollars to spend on terrorism security, and I had a watch list of potential terrorists, I would spend that money investigating those people. I would try to determine whether or not they were a terrorism threat before they got to the airport, or even if they had no intention of visiting an airport. I would try to prevent their plot regardless of whether it involved airplanes. I would clear the innocent people, and I would go after the guilty. I wouldn't build a complex computerized infrastructure and wait until one of them happened to wander into an airport. It just doesn't make security sense.

That's my usual metric when I think about a terrorism security measure: Would it be more effective than taking that money and funding intelligence, investigation, or emergency response -- things that protect us regardless of what the terrorists are planning next. Money spent on security measures that only work against a particular terrorist tactic, forgetting that terrorists are adaptable, is largely wasted.

-- ----------------- R. A. Hettinga <mailto: rah@ibuc.com> The Internet Bearer Underwriting Corporation <http://www.ibuc.com/> 44 Farquhar Street, Boston, MA 02131 USA "... however it may deserve respect for its usefulness and antiquity, [predicting the end of the world] has not been found agreeable to experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'