What then is good for the masses?
Tier 1: potentially inconvenient but maximally secure, in an OPSEC sense (PGP, for instance, though I would personally put Signal here too). Use carefully for security against state-level adversaries.
Tier 2: convenient mainstream applications with strong security but some tradeoffs. Your default choice, security against criminal adversaries. I'd put WhatsApp and iMessage here (but not many others).
Tier 3: unencrypted or dubiously encrypted mainstream applications, unsafe against any adversary, but potentially useful as an endpoint to (cautiously) bootstrap communications. Google Talk and AIM would go here for me.
(Or at least that's how it used to be.)
Sometimes you want plausible deniability, sometimes you want to sign something for all the world to be able to verify.
I agree, but I don't see how that's relevent. This could be added to pgp, without "adopting a new, unverified cryptosystem"
1: security against targeted surveillance from criminals or state-level adversaries. (= spying targets).
2: security against mass surveillance. (= finding targets)
I think it's possible to have Tier 2 system that is Tier 1 against mass surveillance. Individual connections don't have to be proofed against state level actor targeting individuals. It's enough that the whole system works in a way that makes mass surveillance too expensive.
In fact, I think this kind of security is enough to ease most concerns against government surveillance.
- Chatting with friends? = Whatsapp
- International drug deals? != Whatsapp