2005 Low-Cost Traffic Analysis of Tor https://www.freehaven.net/anonbib/cache/torta05.pdf "By making these assumptions, the designers of Tor believe it is safe to employ only minimal mixing of the stream cells... ...This choice of threat model, with its limitation of the adversaries’ powers, has been a subject of controversy... ...Tor, on the other hand assumes a much weaker threat model.. ...we show that even relatively weak adversaries can perform traffic-analysis, and get vital information out of Tor. This means that even non-law-enforcement agencies can significantly degrade the quality of anonymity that Tor provides, to the level of protection provided by a collection of simple proxy servers, or even below." ------- my comment : the attack is based on monitoring the latency of a node while sending an attacker controlled stream through it "Tor exhibits the worst possible behaviour: not enough interference to destroy individ- ual stream characteristics, yet enough to allow the remote measurement of the node’s load." Maybe some tor fanboi knows if this has been somehow fixed? Anyway the article makes it clear that simple cover traffic in not enough to defend against timing attacks.