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From: Michael J Gruber <git@drmicha•warpmail.net>
To: Junio C Hamano <gitster@pobox•com>, Jakub Narebski <jnareb@gmail•com>
Cc: git@vger•kernel.org
Subject: Re: [PATCH 1/2] Documentation/technical: signature formats
Date: Fri, 24 Oct 2014 17:36:19 +0200	[thread overview]
Message-ID: <544A71F3.1020607@drmicha.warpmail.net> (raw)
In-Reply-To: <xmqq7fzshqrb.fsf@gitster.dls.corp.google.com>

Junio C Hamano schrieb am 22.10.2014 um 21:02:
> Michael J Gruber <git@drmicha•warpmail.net> writes:
> 
>> Various formats for storing signatures have accumulated by now.
>> Document them to keep track (and maybe avoid yet another one).
> 
> I haven't looked at the description closely, but it is a good thing
> to describe signature in a tag and in a commit in detail, which we
> failed to do so far.
> 
> The principle is essentially the same between the signature on a tag
> and on a commit: a detached PGP signature over the remainder of the
> object data is created, and then the signature is inserted into an
> appropriate place in the resulting object.  That "appropriate place"
> is influenced by the type and nature of the object.

Yes, the detached signature can't easily be appended to a commit object
the way it follows a tag object. Conversely, signed tag could easily
look like signed commits do (sig in header), but that would require a
migration procedure.

> A mergetag is not fundamentally a "signature" in the above sense,
> though.  It is just a dump of the object content in a regular object
> header field (hence indented by one SP), and its contents having PGP
> SIGNATURE is merely a natural consequence of the object recorded
> being a signed tag.  So the description of it in the same place as
> description for signed tags and signed commits feels a little bit
> out of place, but I do not think of a better place to describe it.

I guess referencing the tag object (like other objects do) rather than
embedding it would have had its merits, but that is beating up a dead
horse. On the other hand, we could migrate to "mergetag sha1" rather
than "mergetag object foo" which is easily distinguished, but only
embedded objects are "safe" against non-aware gits.

> Thanks.

Thanks, Jakub and Junio.

I will correct the wording for the multiline header and put the mergetag
last to make it clearer that it's related but different.

Michael

next prev parent reply	other threads:[~2014-10-24 15:36 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-10-22 15:16 [PATCH 0/2] document signature formats Michael J Gruber
2014-10-22 15:16 ` [PATCH 1/2] Documentation/technical: " Michael J Gruber
2014-10-22 16:57   ` Jakub Narębski
2014-10-22 19:02   ` Junio C Hamano
2014-10-24 15:36     ` Michael J Gruber [this message]
2014-10-24 17:10       ` Junio C Hamano
2014-10-25  8:30     ` Jakub Narębski
2014-10-30 10:19       ` Michael J Gruber
2014-10-22 15:16 ` [PATCH 2/2] Documentation/technical: document push certificate format Michael J Gruber

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