Re: Don't use PGP/GPG signatures in mail that contains patches

From: Jeff King <peff@peff.net>
Date: Jan 18, 2016, 21:48 UTC
Message-ID: <20160118214857.GA24136@sigill.intra.peff.net>
In-Reply-To: <569C3F73.3090805@pb.com>

On Mon, Jan 18, 2016 at 03:27:15AM +0200, Andrey Utkin wrote:

Show 15 quoted lines

> ===== QUOTE =====
> Don't use PGP/GPG signatures in mail that contains patches.
> This breaks many scripts that read and apply the patches.
> (This should be fixable.)
> ===== END QUOTE =====
> 
> This is in Linux' Documentation/email-clients.txt since 2007, and still
> almost nobody signs patch submissions. There are few brave people who
> do, though, and seems it's not the end of world for any "scripts".
> The broken scripts could be an excuse in 2007, but not today.
> 
> Proposal:
> 1. Implement signing option in git-send-email.
> 2. Figure out if anything fails to interoperate.
> 3. Drop the quoted statement or change it to appreciate signing.

I don't know about other receiving scripts, but "git am" will handle signed PGP-MIME out of the box (I didn't try it with inline signatures, but I imagine it would stick the "BEGIN PGP MESSAGE" cruft into the commit message).

However, there's an open question of what to _do_ with such a signature. The email signature does not function as a valid git commit signature. So you are left with one of:

  1. The receiver can verify the origin of the email before applying the
     patch.

  2. The receiver can keep a copy of the email "somewhere", so people
     can later re-verify it, and then hand-verify that it matches what
     got applied.

     That "somewhere" may just be a mailing list archive, but you could
     get fancy with scripts and associate it with the applied commit
     (e.g., using "git notes").

But those are really questions for the project. If you are mailing your patches to Linus, does he actually care about (1)? My general impression of his past opinion is that it's more important to read the patch text than the "From" line. Of course subsystem maintainers and other projects may have different opinions.

I think (2) is more compelling, if only to create a better record in the mailing list archive. Assuming the receivers of your patches don't mind (and I know some people really _don't_ like things like PGP-MIME, because their mail readers are not good at replying in-line to the patches then), I don't it would be a bad thing to teach git-send-email an option to send it.

-Peff