Re: revisiting Autocrypt in notmuch, MVP

["Antoine Beaupré" <anarcat@debian.org>]

On 2023-04-26 12:10:09, Antoine Beaupré wrote:
[...]

> And while autocrypt has a nice beautiful and brilliant spec that does
> everything, that's not what I'm looking at right now. And I don't think
> it's productive to block in this way at this point.
>
> So I made a bespoke implementation that just calls out to sequoia (and
> yes, also gpg, hopefully one day the latter can just go away) to insert
> autocrypt headers to outgoing mail. Here's the implementation:
>
> https://gitlab.com/anarcat/emacs-d/-/blob/354fabad24100f69310dd16a0d30ac3bd96d7244/notmuch-config.el#L14-31
>
> It's brittle, but it works for my case.
>
> I don't think this is something that can be merged as-is in notmuch. It
> depends on gnupg and sequoia, and it's probably incorrect as far as the
> Autocrypt spec is concerned (in particular it doesn't use a UID to
> fingerprint map), but this all seems like things could be improved.

A small update on this: I just realized I was sending autocrypt headers
regardless of whether or not I was signing / encrypting mails. I'm not
sure this is a good idea. The spec says that I "SHOULD", I believe:

https://autocrypt.org/level1.html#header-injection-in-outbound-mail

... but it feels a bit too intrusive... Do I really want to divulge my
cryptographic identity to the world constantly? I'm using ed25519 keys
now, so the header is small, but for other users, that grows the message
size significantly...

Patch is:

https://gitlab.com/anarcat/emacs-d/-/commit/c79495f8580735c23748a62db99b3d9f34f413f5

Interestingly, i had to make a new mml-* function; there's a predicate
to check if a message is encrypted, but not if it's signed, which seems
silly. So I vendored and improved the code, which also feels silly.

So there you go, diverging from the standard already. :)

A.

-- 
You Are What You Is
                        - Frank Zappa\r