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Comment by tptacek | Hacker News Reader

I like the idea of a three-tier threat model:

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.

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PGP doesn't have plausible deniability. It actually has `you can prove anyone else what I said to you', if you sign anything. That's dangerous, so shouldn't be on tier 1.

(Or at least that's how it used to be.)

Is plausible deniability something you want in your communication? Just curious, as this is something I haven't heard before. It seems like non-repudiation would be what you want in your comms.

See https://en.wikipedia.org/wiki/Off-the-Record_Messaging

Sometimes you want plausible deniability, sometimes you want to sign something for all the world to be able to verify.

Got it, thanks. I'd heard of OTR, but never really looked into what it meant. Makes sense now.

Most secure messengers don't have deniability.

So because most of them implement security wrong, we should just accept that as normal? I feel like I'm mis-understanding your point?

I definitely do not think adopting a new, unverified cryptosystem simply to get better "deniability" is a good tradeoff. I see the value, but it's not the most important thing to get right in a secure messenger.

> I definitely do not think adopting a new, unverified cryptosystem simply to get better "deniability" is a good tradeoff.

I agree, but I don't see how that's relevent. This could be added to pgp, without "adopting a new, unverified cryptosystem"

In addition to tiers, I think there are dimensions. Mainly:

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.

Right, key is to make it so expensive that the obsession over mass surveillance becomes economically unhealthy.

Signal "runs on iPhones" which you've deemed to be a bad thing for some reason, so surely that should be tier 2 too. In fact, most things "run on iPhones" so it's kind of an odd argument. What's terrible about running on iPhones?

You misunderstood the point I was making.

Ah yeah, it went totally over my head.

He was holding that up as a popular strawman argument, among the rest in that list.

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