On 15 Dec. 2016, at 06:01, nusenu <nusenu@openmailbox.org> wrote:
How could we avoid an adversary brute-forcing all the possible ASs and days/hours?
I'm not sure I understand what you mean by brute-forcing in this case since I would not suggest any deterministic algorithm (like a hash) that takes an ASname and a timestamp and produces a string but just a AS number -> random id mapping, stored for a day or an hour and deleted after that.
Another way an attacker could take advantage of this: unique AS sign-up rate patterns "everyday there are about x new bridges in AS y" so it doesn't help much if we change the random AS id daily.
If an adversary submits a bridge descriptor from every (popular) AS (in every hour of) every day, they know which AS each bridge is from. Or, alternately, if they submit a bridge descriptor from an AS they are watching, then they know all the bridges in that AS. And they don't actually need to be in the AS to submit a descriptor with an IP address from that AS. T -- Tim Wilson-Brown (teor) teor2345 at gmail dot com PGP C855 6CED 5D90 A0C5 29F6 4D43 450C BA7F 968F 094B ricochet:ekmygaiu4rzgsk6n xmpp: teor at torproject dot org ------------------------------------------------------------------------