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Comment by stse | Hacker News Reader

I think he should stick to writing about cryptography. I read his blog from time to time because of his expertise, but recent posts has just been filled with assumptions and speculations.

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What specific assumptions or speculation in this article do you find objectionable?

Mainly that "detonating PETN is actually very hard" and "no security system [...] on the planet, is designed to catch someone doing this". I remember his analysis to be more detailed than this, but maybe I remember wrong. There were also a post about the predator drone about a week ago, which had some good technical points, but in my opinion was poor from an intelligence perspective.

Those statements are both true, and they support his point that the airport security systems have done some good. I don't see the problem.

I think it's reasonable to point out that almost anyone could have made the same observations based on media reporting over the past several weeks; it took no particular skill or experience to note that no security system is perfect or to note that liquid explosives are hard to detonate.

Perhaps it doesn't take much skill, but that observation doesn't really jive with my not having seen these points in print or on the news since the incident. Bruce's blurb was the first time I heard anything about either aspect of the case.

houseabsolute is right on this. You do not see any blasting caps, or explosive devices, military grade or not, made with PETN, that do not have a trigger. Fancy-named explosives like C-4 get all the glory in the movies, but tricky bits like the triggers don't get any attention.

Thankfully for us, the same properties that make a trigger a trigger also make triggers kind of a pain in the ass to manufacture. If it will blow up easily on the plane, it'll blow up even more easily when you're trying to make it from scratch or if you're prying it out of an artillery shell (how in God's name one would try to attempt the latter, I have no idea).

Yes, you need a detonator, but it still not "very hard" to detonate. It's actually relatively sensitive to impact, and very sensitive to explosive initiation. If you call (basically) the most sensitive secondary explosive for "very hard to detonate" (like he did) you are probably not very experienced with explosives, which was my point in the first place. And while I'm very far from an explosives expert, my experiences are not from the movies.

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