Proposal 162: Publish the consensus in multiple flavors

[Marcus Griep]

On Mon, 2009-06-15 at 14:19 -0400, Nick Mathewson wrote:
> On Fri, Jun 12, 2009 at 11:10:09PM -0400, Roger Dingledine wrote:
> > On Fri, May 15, 2009 at 01:05:41PM -0400, Nick Mathewson wrote:
> > >    Our past approach to cases like this has been to shovel all of
> > >    the data into the consensus document.  But this is rather poor
> > >    for bandwidth.  Adding a single SHA256 hash to a consensus for
> > >    each router increases the compressed consensus size by 47%.  In
> > >    comparison, replacing a single SHA1 hash with a SHA256 hash for
> > >    each listed router increases the consensus size by only 18%.
> > 
> > SHA256's are still huge. It's a real shame there aren't accepted hash
> > functions that use only 20 bytes.
> 
> I think we're going to have to live with this, unless we want to be
> crypto-weirdos and say that our hash function is the first 20 bytes of
> SHA256 or something else horribly under-analyzed like that.

One option is to use SHA224, SHA256's shorter cousin. It would lower the
size from 32 bytes to 28 bytes and is a part of the FIPS standard.
-- 
Marcus Griep
GPG Key ID: 0x070E3F2D
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