Seems like more research needs to go into preventing traffic confirmation attacks: <a href="https:&#x2F;&#x2F;blog.torproject.org&#x2F;blog&#x2F;tor-security-advisory-relay-early-traffic-confirmation-attack&#x2F;" rel="nofollow">https:&#x2F;&#x2F;blog.torproject.org&#x2F;blog&#x2F;tor-security-advisory-relay...</a><p>&quot;A traffic confirmation attack is possible when the attacker controls or observes the relays on both ends of a Tor circuit and then compares traffic timing, volume, or other characteristics to conclude that the two relays are indeed on the same circuit. If the first relay in the circuit (called the &quot;entry guard&quot;) knows the IP address of the user, and the last relay in the circuit knows the resource or destination she is accessing, then together they can deanonymize her.&quot;<p>Interesting technical problem. They patched it, obviously, but similar attacks are still possible. It does say more research needs to be done, when that post was published. Obviously the method they used to send and receive signals from one side to the other doesn&#x27;t work anymore, but statistical methods presumably do. Sort of like this:<p><a href="https:&#x2F;&#x2F;mice.cs.columbia.edu&#x2F;getTechreport.php?techreportID=556&amp;format=pdf" rel="nofollow">https:&#x2F;&#x2F;mice.cs.columbia.edu&#x2F;getTechreport.php?techreportID=...</a><p>Seems like a very difficult problem to solve.