From mk@dee.su Fri Jul 6 02:38:15 2018 From: Maxim Kammerer To: cypherpunks-legacy@lists.cpunks.org Subject: Re: [tor-talk] End-to-end correlation for fun and profit Date: Fri, 06 Jul 2018 02:38:15 +0000 Message-ID: <172289275233.3881296.4587493126333795896.generated@mail.pglaf.org> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="===============4944156671970659966==" --===============4944156671970659966== Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Sat, Aug 25, 2012 at 1:12 AM, Mike Perry wrot= e: > 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/S= ep-2008/msg00016.html 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=3D25% and different correlation accuracies (leaving the other numbers intact): (using b bc -lb) ca =3D 0.999 pm =3D (1/5000) * (0.25)^2 ca*pm / (pm*ca + (1-pm)*(1-ca)) ca =3D 0.999 .01233363786760166917 ca =3D 0.9999 .11110246894375430565 ca =3D 0.99999 .55555617284636495961 ca =3D 0.999999 .92592671467910125759 ca =3D 0.9999999 .99206358969515668554 ca =3D 0.99999999 .99920064946444143613 ca =3D 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. --=20 Maxim Kammerer LibertC) Linux: http://dee.su/liberte _______________________________________________ tor-talk mailing list tor-talk(a)lists.torproject.org https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk ----- End forwarded message ----- --=20 Eugen* Leitl leitl 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 --===============4944156671970659966==--