From: Michael J Gruber <git@drmicha.warpmail.net>
To: Duy Nguyen <pclouds@gmail.com>, Jeff King <peff@peff.net>
Cc: Patrick Schleizer <patrick-mailinglists@whonix.org>,
Git Mailing List <git@vger.kernel.org>,
whonix-devel@whonix.org, mikegerwitz@gnu.org
Subject: Re: How safe are signed git tags? Only as safe as SHA-1 or somehow safer?
Date: Mon, 24 Nov 2014 11:15:34 +0100 [thread overview]
Message-ID: <54730546.7000200@drmicha.warpmail.net> (raw)
In-Reply-To: <CACsJy8D-W_YrxMgUDScSmkNBKMVpRu_Kc0k6nsfyhmoLg5HBjg@mail.gmail.com>
Duy Nguyen schrieb am 24.11.2014 um 02:23:
> On Tue, Nov 18, 2014 at 4:26 AM, Jeff King <peff@peff.net> wrote:
>> Yes, it is only as "safe as SHA-1" in the sense that you have GPG-signed
>> only a SHA-1 hash. If somebody can find a collision with a hash you have
>> signed, they can substitute the colliding data for the data you signed.
>
> I wonder if we can have an option to sign all blob content of the tree
> associated to a commit, and the content of parent commit(s). It's more
> expensive than signing just commit/tag content. But it's also safer
> without completely ditching SHA-1.
>
This amounts to hashing the blob content with whatever hash you told
your gpg to use (hopefully not sha1 ;) ) and signing that.
You're free to do that now and store the signature wherever your
toolchain deems fit, say in a note or an annotated tag. But that
approach won't sign the history, that is: If you are concerned about the
breakability of sha1, then history is "possibly broken" no matter how
you sign a commit object whose "parent" entry is based on the sha1 of
its parent object.
Cheers
Michael
next prev parent reply other threads:[~2014-11-24 10:15 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-16 15:31 How safe are signed git tags? Only as safe as SHA-1 or somehow safer? Patrick Schleizer
2014-11-17 21:26 ` Jeff King
2014-11-21 23:01 ` Patrick Schleizer
2014-11-21 23:32 ` Jason Pyeron
2014-11-22 19:48 ` Jeff King
2014-11-22 19:43 ` Jeff King
2014-11-25 12:59 ` Fedor Brunner
2014-11-24 1:23 ` Duy Nguyen
2014-11-24 10:15 ` Michael J Gruber [this message]
2014-11-24 11:44 ` Duy Nguyen
2014-11-25 10:41 ` Duy Nguyen
2014-11-24 15:51 ` Jeff King
2014-11-24 18:14 ` Nico Williams
2014-11-25 1:16 ` Duy Nguyen
2014-11-25 1:23 ` Jonathan Nieder
2014-11-25 1:52 ` Duy Nguyen
2014-11-25 3:40 ` Stefan Beller
2014-11-25 3:47 ` Jeff King
2014-11-25 10:55 ` Duy Nguyen
2014-11-25 17:23 ` Junio C Hamano
2014-11-25 11:07 ` brian m. carlson
2014-11-24 0:52 bancfc
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