If the FBI wanted car manufacturers to design seat belts and airbags with murderers and rapists in mind, it wouldn't have taken months of debate to reject the idea. Just because we've entered the domains math and CS, we get months of dithering, contemplating whether or not to force domestic companies to install complex new self-destruct functions into their products.

Al-Qaeda have been using Mujahedeen Secrets — a Windows-based encryption app — since 2007. Legislators should test whether potential new laws can have any impact on such uncontroversially abhorrent software. If, like split keys, they fail the Mujahedeen Secrets test, they can only damage our collective security.