Re: Hash algorithm analysis

From: Jonathan Nieder <jrnieder@gmail.com>
To: Dan Shumow <danshu@microsoft.com>
Cc: Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	"brian m. carlson" <sandals@crustytoothpaste.net>,
	Junio C Hamano <gitster@pobox.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Edward Thomson <ethomson@edwardthomson.com>,
	Git Mailing List <git@vger.kernel.org>,
	demerphq <demerphq@gmail.com>, Adam Langley <agl@google.com>,
	"keccak@noekeon.org" <keccak@noekeon.org>
Subject: Re: Hash algorithm analysis
Date: Thu, 2 Aug 2018 19:57:09 -0700	[thread overview]
Message-ID: <20180803025709.GD197924@aiede.svl.corp.google.com> (raw)
In-Reply-To: <MWHPR21MB01738A46E37527E45E950937C42F0@MWHPR21MB0173.namprd21.prod.outlook.com>

Hi Dan,

Dan Shumow wrote:

[replying out of order for convenience]
> However, I agree with Adam Langley that basically all of the
> finalists for a hash function replacement are about the same for the
> security needs of Git.  I think that, for this community, other
> software engineering considerations should be more important to the
> selection process.

Thanks for this clarification, which provides some useful context to
your opinion that was previously relayed by Dscho.

[...]
> So, as one of the coauthors of the SHA-1 collision detection code, I
> just wanted to chime in and say I'm glad to see the move to a longer
> hash function.  Though, as a cryptographer, I have a few thoughts on
> the matter that I thought I would share.
>
> I think that moving to SHA256 is a fine change, and I support it.

More generally, thanks for weighing in and for explaining your
rationale.  Even (especially) having already made the decision, it's
comforting to hear a qualified person endorsing that choice.

Sincerely,
Jonathan