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We doubt it. Here's something recently posted at Reddit:
Anything in Tor is completely traceable. This is an important point, so I'll reiterate it in big scary letters:
TOR IS COMPLETELY TRACEABLE
Any low-latency mixnet is. There's no two ways about it. Anyone who can observe a sufficiently large part of the internet over time can correlate your traffic to that of the server and get a pretty good idea that it's you.
I'll observe your IP connecting to an entry node and sending 13981 bytes to it. Then I'll observe an exit node sending exactly 13981 bytes to a server a second later. That's you, with an overwhelming probability. It's a bit of a simplification, but it's really that easy. I just have to be powerful enough to be able to observe large parts of the internet, since Tor nodes are spread around the globe.
Anything in Tor is completely traceable. This is an important point, so I'll reiterate it in big scary letters:
TOR IS COMPLETELY TRACEABLE
Any low-latency mixnet is. There's no two ways about it. Anyone who can observe a sufficiently large part of the internet over time can correlate your traffic to that of the server and get a pretty good idea that it's you.
I'll observe your IP connecting to an entry node and sending 13981 bytes to it. Then I'll observe an exit node sending exactly 13981 bytes to a server a second later. That's you, with an overwhelming probability. It's a bit of a simplification, but it's really that easy. I just have to be powerful enough to be able to observe large parts of the internet, since Tor nodes are spread around the globe.
I love how they quote "something posted at Reddit." That's such a credible source of information!
This oversimplified quote basically discredits the entire article since they think this is correct. Tor is NOT traceable this way. This is an important point, so I'll reiterate it in big scary letters:
TOR IS NOT COMPLETELY TRACEABLE IN THE WAY PORTRAYED ABOVE
You can't observe the first node in an onion routing network "sending 13981 bytes to it." These plaintext bytes would be wrapped in 2 layers of encryption (hence, onion), so you might be able to guess with some sort of margin of error how big the decrypted payload might be, and maybe observe it somewhere else in the world and do some timing analysis, but all of that is REALLY hard to do. The "a second later" part is particularly silly - how do you know it's only going to take 1 second? What if that exit node is sending out packets ever millisecond (which most are)?
Care to explain this:
http://prisms.cs.umass.edu/brian/pubs/wright-tissec.pdf (page #13)
