Now let’s ignore the fact that you’ve just leaked your key request to an untrusted server via HTTP. At the end of this process you should have the right key with high reliability. Right?
Except maybe not: if you happen to do this with GnuPG 2.0.18 -- one version off from the very latest GnuPG -- the client won’t actually bother to check the fingerprint of the received key.
Adding forward secrecy to asynchronous offline email is a much bigger challenge, but fundamentally it’s at least possible to some degree. While securing the initial ‘introduction’ message between two participants may be challenging, each subsequent reply can carry a new ephemeral key to be used in future communications. However this requires breaking changes to the PGP protocol and to clients -- changes that aren’t likely to happen in a world where webmail providers have doubled down on the PGP model.
I realize I sound a bit cranky about this stuff. But as they say: a PGP critic is just a PGP user who’s actually used the software for a while. At this point so much potential in this area and so many opportunities to do better. It’s time for us to adopt those ideas and stop looking backwards.
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