If I had known they had GPG signed hashes, my work flow downloading the distro for the first time during the compromise would have been as follows:

1. Get key id of the key used to sign the hashes. 2. Google for key id. Hmm, no one's used the key id before, that's odd. Not in my web of trust. And it doesn't match the key id mentioned on other forums/scripts/sites. I'll definitely hold off until I can verify the key directly with one of the distro maintainers.

Even if you haven't previously established trust, GPG can be an extremely valuable ally.

You can use gpg on windows or macosx as well to verify the signed hashes.

As linked in the blog post in my other comment, tails explains things quite well:

https://tails.boum.org/download/index.en.html#verify

True, but the site has to be compromised at the moment you are downloading the keys (not anytime later!), and then all your further installations have to me MITM-ed or you would take notice. Not so trivial for attacker anymore.

Ideally, the keys should be distributed in safe fashion too, so this whole question should be moot.

> ...and then all your further installations have to me MITM-ed or you would take notice. Not so trivial for attacker anymore.

Though perhaps more trivial when the attacker has helpfully provided your operating environment.

The user interface/experience of PGP/GPG is not great, and that could do with fixing. However if you already understood how to use PGP (and granted that's unlikely for the users Mint targets), then you would not have been caught out by this.