From: Sam Vilain <sam@vilain.net>
Date: Mon, 02 Mar 2015 19:38:00 GMT
Subject: Re: weaning distributions off tarballs: extended verification of git tags
Message-ID: <54F4BC18.5060702@vilain.net>
In-Reply-To: <20150302181230.GA31798@kitenet.net>

On 03/02/2015 10:12 AM, Joey Hess wrote:
> I support this proposal, as someone who no longer releases tarballs
> of my software, when I can possibly avoid it. I have worried about
> signed tags / commits only being a SHA1 break away from useless.
>
> As to the implementation, checksumming the collection of raw objects is
> certainly superior to tar. Colin had suggested sorting the objects by
> checksum, but I don't think that is necessary. Just stream the commit
> object, then its tree object, followed by the content of each object
> listed in the tree, recursing into subtrees as necessary. That will be a
> stable stream for a given commit, or tree.

I would really just do it exactly the same way that git does: checksum 
the objects including their headers with the new hashes.  I have a hazy 
recollection of what it would take to replace SHA-1 in git with 
something else; it should be possible (though tricky) to do it lazily, 
where a tree entry has bits (eg, some of the currently unused file mode 
bits) to denotes which hash algorithm is in use for the entry.  However 
I don't think that got past idea stage...

Sam