Re: I lost my commit signature

From: Michael J Gruber <git@drmicha.warpmail.net>
Date: Jun 15, 2016, 07:07 UTC
Message-ID: <be771366-00a7-6c20-2623-5fa54b8e19b7@drmicha.warpmail.net>
In-Reply-To: <20160615043450.GA3975@sigill.intra.peff.net>

Jeff King venit, vidit, dixit 15.06.2016 06:34:

Show 24 quoted lines

> On Wed, Jun 15, 2016 at 12:27:15PM +0800, ZhenTian wrote:
> 
>> I got two more lines from gpg -v during commit with -S:
>> ```
>> gpg: writing to stdout
>> gpg: RSA/SHA1 signature from: "2EF2AD6E Tian Zhen <tianzhen@honovation.com>"
>> ```
>>
>> after I commit, I push it to remote, but someone had pushed before to
>> master branch, so I pull on master branch(`git pull --rebase`), then I
>> check my commit via `git log --show-signature`, there is no signature
>> in it, so I commit it with --ament and -S again, the signature is come
>> back.
>>
>> I haven't check signature before push, because I have checked four
>> commits before, every commit is fine.
>>
>> I don't know whether the `git pull` influenced signature or not.
> 
> Ah, so the problem is probably that you had a signature _initially_, but
> that it did not survive the rebase. Which makes sense, as rebase would
> need to re-sign.  It does not by default, but you can tell it to do so
> with "-S". Or you can set `commit.gpgsign`, which should sign in both
> cases.

While it's clear that a rebase invalidates the signature, we could try to be more helpful here, especially given the fact that (with our model) you can't sign a commit afterwards any more.

commit.gpgsign signs everything, but there should be a mode for re-signing signed commits, or at least a warning that rebase dropped a signature so that you can --amend -S the last commit.

Michael