> Mujahedeen Secrets (first release: 2007), Al-Queda’s own encrypted messaging software. Those developers aren’t going to respond to a US court order.
Even with that, you are now forcing the terrorists to roll their own encryption. The likelihood of finding an exploit in Mujahadeen Secrets is likely much higher than finding an exploit in Apple Messenger or WhatsApp or something by djb or Moxie, etc. In addition, Mujahadeen is likely having to be side loaded - you won't find it in the App Store. This gives a chance to try to hack a single storage location to have a trojan horse version spread through their network. Finally, it affects recruiting. Basically only someone already comitted will go to the trouble of having Mujahadeen Secrets on their device, whereas a lot more people could be expected to have a common end-to-end messenger on their device. So overall, thinking from a purely law enforcement, anti-terrorist perspective, it would still be better for them to not have e2e in widely used apps, even if the terrorists tried to develop their own app.