Schneier on Security

Roger • February 10, 2007 4:55 AM

For some reason, this blog entry was just showing up as a blank page for me, so I’m reading it through the Google cache. Hopefully, the attempt to post will also work.

@SteveJ:
“Juan Carlos de Menezes was slandered after his death. He was variously accused of wearing a coat on a hot day (“acting hinky”), running from police, and associating with terrorists. None of that turned out to be true, but those making the hinkiness accusation were confident that, if it were believed that he were indeed acting hinky, the killing would be that much closer to acceptable.”

The way you phrase this quote makes it sound as if you think that all these accusations of suspicious behaviour were made by the police. In fact, none of them were. The first two of these reports came from members of the public being interviewed by the press shortly after the tragedy, and the police in fact denied them all right from the outset. (The third accusation I have never heard before.) If anything, this segues into Bruce’s post about the unreliability of eyewitnesses.

@Steve:
“An empirical way to look at this would be to look at the false positive rate for tips when police put out a public request to identify a criminal based on a sketch.”
The simple answer is that police continue to do this, at least for serious crimes; hence, the cost of the false positives is obviously manageable, and less than the benefit at least in the case of serious offences. More specifically, my anecdotal experience is that the false positive rate goes really high (but still manageable) after a media frenzy, the rest of the time it just isn’t an issue.

“Looks like even the suicide bombers sometimes do have nerves.”

Yes. The Israeli experience has been that suicide bombers are usually sweating with fear during their attacks. The extreme nervousness is a strong indicator that something is going on — it may not be a suicide bombing, but if not it is most likely some other criminal offence. The idea that suicide bombers have made their peace with God and go to their (empty) graves calm as saints is nonsense. (They are also badly afected by the fear of failure, and ridicule. Whenever a bomber fails in a particularly embarrassing way, recruitment drops for some time afterward.) The one significant exception is that in recent years some “suicide” bombers have been simpletons who likely did not understand they were carrying a bomb.

@Clive Robinson:
“However one of the results well known to the Israelis (long before the de Menzies shooting) was that the bombers moved first to tilt switches, and then remote radio detonation.”

Do you have any reliable reference for that? The first idea (tilt switches) is, to be blunt, disastrously silly. Dead man’s switches have been experimented with but are avoided because they score too many “own goals”. Tilt switches would be even worse in this regard (what do you do, recruit on the basis of good posture?!?) I’m sure we would be ecstatically happy if suicide bombers would be foolish enough to adopt them.

As for remote control detonation, I have heard of this being done, but it wasn’t a countermeasure to bombers getting shot; it was to detonate bombs strapped to mentally deficient “volunteers” who likely had no idea they were carrying bombs.

Neither is an effective countermeasure anyway, since part of the idea of shooting a bomber is that the bomb may still go off, but even in that event, shooting him causes the detonation to be at a place not of his own chosing (and hence, likely to minimise rather than maximise casualties.) After all, the whole point of suicide bombing is that it provides a poor man’s terminal guidance system. If the detonation will be at some random location, why bother to sacrifice a jihadi to do it?

Various comments re racial profiling: it’s worth pointing out that race was one — although only one — of the elements in Woltinsky’s “profile”. It may be unpopular to say it, but the fact is that there is no fundamental law that says that it is impossible for race to be a valid parameter, and this is one example whre it was: suicide bomb attacks against Israelis in Israel are almost exclusively performed by Arabs. If it makes you more comfortable, say that not being an Arab would lower the likelihood that the guy was a bomber — but that is, in fact, exactly the same as saying that being an Arab increased that likelihood.

@Too Scared to Say:
“I can’t see any systematic lesson to be learned other than sometimes suspicion has benefits. We already knew that. The core debate is, what are those benefits compared with its costs.”

The answer is that on balance, the benefits of suspicion — at about the levels of suspicion/trust balance most people actually have — are positive. We conclude this from the fact that it has evolved this way, with a very fast acting selective pressure (people who are too trusting get murdered in their beds, people who are too suspicious never fall in love and have a family.)