[tor-relays] bandwidth authority algorithm is cracked

[Roger Dingledine]

On Wed, Jan 22, 2014 at 02:33:21PM -0500, Roger Dingledine wrote:
> The consensus weight is computed using
> a) the relay's self-advertised bandwidth in its descriptor:
> https://gitweb.torproject.org/torspec.git/blob/HEAD:/dir-spec.txt#l389
> b) the ratios of bandwidth weights for various types of relays:
> https://gitweb.torproject.org/torspec.git/blob/HEAD:/dir-spec.txt#l2137
> and
> c) the result of the active measurements from the bandwidth authorities:
> https://gitweb.torproject.org/torflow.git/blob/HEAD:/NetworkScanners/BwAuthority/README.BwAuthorities
> https://gitweb.torproject.org/torflow.git/blob/HEAD:/NetworkScanners/BwAuthority/README.spec.txt

I take it back -- the consensus weight is computed using 'a' and 'c'
above, and then clients consider 'b' and the weights when selecting
relays.

--Roger