[contravariant]

Sure, but exactly how would you build something that's robust against that kind of access?

If you leave cryptographic keys lying around unprotected they should be assumed to be compromised.

[klyrs]

Signal has a PIN, too. If that's required for the transfer, then it would prevent this in the case of brief, surreptitious access. A hostage scenario is impossible

[contravariant]

Well, maybe, but 'brief' is doing a lot of the heavy lifting in that sentence.

[klyrs]

> There are many cases where an attacker can access a device for a short time and/or without the owner realizing that the phone was tampered with.

This is what you originally responded to. I paraphrased it. The "heavy lifting" meme that you've employed is rarely more than a shallow dismissal. Be better.