Re: weaning distributions off tarballs: extended verification of git tags

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