From: Junio C Hamano <gitster@pobox.com>
To: Stefan Beller <sbeller@google.com>
Cc: tom@oxix.org, Matthieu Moy <Matthieu.Moy@imag.fr>,
"git\@vger.kernel.org" <git@vger.kernel.org>
Subject: Re: [Request for Documentation] Differentiate signed (commits/tags/pushes)
Date: Mon, 06 Mar 2017 15:03:15 -0800 [thread overview]
Message-ID: <xmqq8toiypn0.fsf@junio-linux.mtv.corp.google.com> (raw)
In-Reply-To: <xmqqshmqm4ur.fsf@junio-linux.mtv.corp.google.com> (Junio C. Hamano's message of "Mon, 06 Mar 2017 14:13:00 -0800")
Junio C Hamano <gitster@pobox.com> writes:
> Stefan Beller <sbeller@google.com> writes:
>
>> What is the difference between signed commits and tags?
>> (Not from a technical perspective, but for the end user)
> ...
>> A signed push can certify that a given payload (consisting
>> of multiple commits on possibly multiple branches) was transmitted
>> to a remote, which can be recorded by the remote as e.g. a proof
>> of work.
> ...
> A signed push is _NOT_ about certifying the objects in the history
> DAG. It is about certifying the _intent_ of pointing _REFS_ into
> points in the object graph.
> ...
> Historically, "tag -s" came a lot earlier. When a project for
> whatever reason wants signature for each and every commit so that
> they somehow can feel good, without "commit -s", it would have made
> us unnecessary work to scale tag namespace only because there will
> be tons of pointless tags. "commit -s" was a remedy for that.
While we are enumerating them, it is worth mentioning the mergetag
header of a commit object.
This is added to a (merge) commit object when you merged a signed
tag that points at a commit, and the intent is to eliminate the need
to _keep_ the ref around that is created only for the purpose of
"please pull from me, I tagged and signed the tip of the history I
want you to pull" request. From that point of view, you could say
it is also reducing the load on refs/tags/ namespace, but more
importantly by not requiring the ref around, it allows you to verify
that the merge commit merged the correct tag with _only_ the commit
object by reproducing the payload of the signed tag that was merged
in the commit object in full.
next prev parent reply other threads:[~2017-03-07 1:00 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-06 19:59 [Request for Documentation] Differentiate signed (commits/tags/pushes) Stefan Beller
2017-03-06 22:13 ` Junio C Hamano
2017-03-06 22:52 ` Stefan Beller
2017-03-07 0:08 ` Junio C Hamano
2017-03-07 0:58 ` Stefan Beller
2017-03-06 23:03 ` Junio C Hamano [this message]
2017-03-06 23:59 ` Jakub Narębski
2017-03-07 0:16 ` Junio C Hamano
2017-03-07 7:16 ` Matthieu Moy
2017-03-07 9:23 ` Jeff King
2017-03-07 9:45 ` Tom Jones
2017-03-07 22:19 ` Stefan Beller
2017-03-08 5:41 ` Jeff King
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