On Sat, Aug 25, 2012 at 1:12 AM, Mike Perry <mikeperry@torproject.org> wrote:

The Raccoon has made a believer out of me, but there are some limits to both of his/her proofs.. The full proofs can still be found here: http://web.archive.org/web/20100416150300/http://archives.seul.org/or/dev/Se...

Wrt. the first proof, it seems to me that the assumed correlation accuracy rate of 99.9% is incredibly low, and I think that the Raccoon recognized that by referring to sampling and retention at the end of his post. With the targeted attack that's similar to b Example 3b in Raccoon's post that I described in my previous comment here, where one analyzes all exit traffic without missing packets, I would expect the correlation accuracy (and as a result, match confidence) to exponentially approach 100% very quickly with the number of relevant packets seen, and extremely quickly if the traffic is interactive (i.e., browsing). Actually, c/n of 30% in b Example 3b is close to the 25% that's discussed in the OP here, so let's redo the example with c/n=25% and different correlation accuracies (leaving the other numbers intact): (using b bc -lb) ca = 0.999 pm = (1/5000) * (0.25)^2 ca*pm / (pm*ca + (1-pm)*(1-ca)) ca = 0.999 .01233363786760166917 ca = 0.9999 .11110246894375430565 ca = 0.99999 .55555617284636495961 ca = 0.999999 .92592671467910125759 ca = 0.9999999 .99206358969515668554 ca = 0.99999999 .99920064946444143613 ca = 0.999999999 .99992000739924807495 So reducing correlation accuracy error to 10^-9 will give you 99.99% confidence in end-to-end correlation match. I suspect that a few seconds of interactive traffic will give you a correlation accuracy that's much better than a 10^-9 error. -- Maxim Kammerer LibertC) Linux: http://dee.su/liberte _______________________________________________ tor-talk mailing list tor-talk@lists.torproject.org https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk ----- End forwarded message ----- -- Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE