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Comment by wayfinder | Hacker News Reader

I never said the keys are sent to any servers.

They keys are still generated and kept using software they wrote.

Second, they also control who they trade the keys between.

This is contrasted to some chat apps (which are painful asf to use) where you have to manually exchange keys, meaning you have to engage with the party you want to talk to and so you can confirm who you are really encrypting messages for. It’s physically impossible to be given the wrong person’s key because you personally had to get them.

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> They keys are still generated and kept using software they wrote.

This is a prerequisite for forward secrecy, which is arguably much more relevant.

> It’s physically impossible to be given the wrong person’s key because you personally had to get them.

Does that matter at all if the (in your threat model non-trustworthy) software just exfiltrates all messages?

If you don't trust your encryption software, it's game over (unless it encrypts everything fully deterministically and you regularly audit its outputs).

Well these apps don’t even let you verify the keys even if you wanted to, so you can’t even tell if it’s being man-in-the-middle’d.

Some people said they are finally adding key transparency features to let you do that, but it should have been there since the start. Something a lot of people already use called SSH literally has had that since forever. It’s like basic 101 cryptography if you design an encrypted protocol that isn’t using a trusted third party for key verification (like certificate authorities in TLS/SSL).

If you implement ANY encrypted protocol, key verification is extremely important. If you aren’t verifying keys are possessed only by your recipient, you cannot verify who can read your message.

WhatsApp has always allowed key verification (at least since they've supported encryption), as far as I remember.

> It’s like basic 101 cryptography if you design an encrypted protocol that isn’t using a trusted third party for key verification (like certificate authorities in TLS/SSL).

SSH/TOFU is one model, PKI is another. Both have their respective merits, especially when combining PKI with certificate transparency.

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