Short of banning math, how exactly can you prevent people from using strong encryption?
Even assuming the government can convince a lot of big corporations to put backdoors in their products, tech literate people will just use niche open source encryption for their own communications. Terrorists, or people that want to do evil, will switch to using secure channels - so the only people you will be able to monitor via sig-int will be average people that are not particularly tech literate. That doesn't seem like such a huge gain to me.
Short of banning math, how exactly can you prevent people from using strong encryption?
There are plenty of things that are technically possible but illegal. Most things that are illegal are physically possible to perform if I so wished. The efficacy of law is never 100%, how often people break it is often based on the ease to do so, the ease to not get caught, the scale of punishment, personal morals, interpersonal pressure, and societal standards.
I think the distinction is that cryptography is much closer to thought-crime than to any physical crime. It's on the continuum of banning speaking in private. There are a lot of ways to slice it, but it boils down to privacy being illegal per se. It would be unconscionable by the majority if the implications were clearly understood, but because it's "technology" somehow the fearmongers are able to spin it (as they do so many things) as a national security issue.
I think the point is to carve the division between tech-literate and common communications in stone -- to prevent privacy and security from ever going mainstream. If encryption is outlawed, people using it will be easy to identify and manipulate.
Bingo. There's no way these guys can truly believe that e.g., forcing Apple to decrypt iPhones on demand is going to put a big dent in terrorism. I guess they are a) hoping to get an upper hand on a few small-time/unsophisticated criminals and don't mind stretching the truth to sell it to the public, or b) they view this as the first of many long-term steps in killing encryption/privacy in the US altogether, or c) they plan to deploy this much more widely than they are letting on, possibly even internationally through things like trade agreements (in which case it could actually be useful for counter-terrorism.)
I would imagine here in the UK our politicians will use this narrative:
* Evildoers aren't born knowing how to use tor and having all the right onion urls memorised. New recruits are onboarded/radicalised with tools the average person regularly uses. Like facebook, twitter, gmail, https-encrypted websites and so on.
* Active terrorists learn to use encryption properly before they start committing crimes, so we can't monitor the active terrorists. As our only option is to monitor new and prospective recruits, we'll have to monitor people who aren't yet committing any crimes. As we'll be monitoring the widest part of the recruitment funnel, monitoring huge numbers of innocent people is just the only option.
* People might be recruited through channels we're not already aware of. When a terrorist is recruited we need to be able to find out how they were recruited, so we can find new channels we need to monitor. And it could be months or even years between the recruit learning to use effective encryption and them being identified as a terrorist. So we need to store an internet history for every person for several years.
* Privacy? Well, there will be strict legislative safeguards in place of course! Unfortunately all the work will be top secret so only insiders can audit compliance and it'll be illegal for them to take any evidence of wrongdoing to the press. But the legislative framework will be very strict, yes sireee.
* This is the best option we have to keep our children safe http://www.bbc.co.uk/news/uk-31575908 you wouldn't want any more schoolgirls going off to join ISIS now, would you?
Even assuming the government can convince a lot of big corporations to put backdoors in their products, tech literate people will just use niche open source encryption for their own communications. Terrorists, or people that want to do evil, will switch to using secure channels - so the only people you will be able to monitor via sig-int will be average people that are not particularly tech literate. That doesn't seem like such a huge gain to me.