[r00fus]

It was more than just security-by-obscurity; these guys refused to use an existing package that would solve their issues... the "mujahaddin secrets" package (ostensibly jihadist in origin) that did implement AES cyphers.

Guess what, if you're so purist you can't trust experts in your own field because they use "contaminated knowledge", then you better be a true genius, or you're not going to be very effective.

[waqf]

It sure is convenient that the people who have such bad judgement that they want to plant bombs on airliners also have such bad judgement that they roll their own crypto.

And I don't think it's a coincidence. It really boils down to them not being able to figure out which people (especially, which "authorities") to trust.