From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff King Subject: Re: How safe are signed git tags? Only as safe as SHA-1 or somehow safer? Date: Mon, 24 Nov 2014 22:47:31 -0500 Message-ID: <20141125034730.GB19161@peff.net> References: <5468C33E.2080108@whonix.org> <20141117212657.GC15880@peff.net> <20141125012359.GR6527@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Jonathan Nieder , Nico Williams , git discussion list , "brian m. carlson" To: Duy Nguyen X-From: git-owner@vger.kernel.org Tue Nov 25 04:47:36 2014 Return-path: Envelope-to: gcvg-git-2@plane.gmane.org Received: from vger.kernel.org ([209.132.180.67]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Xt76F-00083r-TM for gcvg-git-2@plane.gmane.org; Tue, 25 Nov 2014 04:47:36 +0100 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751789AbaKYDrc (ORCPT ); Mon, 24 Nov 2014 22:47:32 -0500 Received: from cloud.peff.net ([50.56.180.127]:44604 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1750770AbaKYDrb (ORCPT ); Mon, 24 Nov 2014 22:47:31 -0500 Received: (qmail 27216 invoked by uid 102); 25 Nov 2014 03:47:32 -0000 Received: from Unknown (HELO peff.net) (10.0.1.1) by cloud.peff.net (qpsmtpd/0.84) with SMTP; Mon, 24 Nov 2014 21:47:32 -0600 Received: (qmail 26385 invoked by uid 107); 25 Nov 2014 03:47:30 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.84) with SMTP; Mon, 24 Nov 2014 22:47:30 -0500 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Mon, 24 Nov 2014 22:47:31 -0500 Content-Disposition: inline In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Tue, Nov 25, 2014 at 08:52:58AM +0700, Duy Nguyen wrote: > On Tue, Nov 25, 2014 at 8:23 AM, Jonathan Nieder wrote: > > I think the biggest obstacle is the upgrade path. ;-) > > In the worst case we can always treat new repos as a different VCS. So > people will need a migration from SHA-1 to the new format, just like > they migrate from SVN/CVS to Git. Painful but simple. Maybe we can fix the tree-sorting order while we are at it. :) More seriously, there may come a day when we are ready to break compatibility completely with a new "Git v3.0" (2.0 is already taken, of course). I do not have immediate plans for it, but it's possible that multiple factors may make such a move desirable sometime in the next 10 years, and that would be a good time to jump hash algorithms, as well. So it's possible that procrastinating on SHA-1 issues may be the least painful route. Or it may just be pushing off the day of pain. :) -Peff