--- On Thu, 10/1/09, Brian Mearns <bmea...@ieee.org> wrote: > My understanding is that Tor user's are responsible (via their client) > for creating their own circuit, and that this is typically > done at random. However, are there any safeguards in place to > ensure that it is random, and would this be desirable? I would imagine > that attackers might try to choose specific circuits in order to learn > more about particular nodes, and the network in general. Would > preventing this behavior be helpful, and if so, would it be helpful > enough to offset any disadvantage it causes for legit users?
I do not think that this would be desirable, random circuits have their downfalls. Other's can elaborate why better I am sure. > My idea is pretty simple. Instead of creating the circuit > through black-box means (relying on their local RNGs, for > instance), the user would create some seed value S, and then > a list of random adjustment values, R0, R1, R2,..., one for > each relay in the circuit. The S value > would be used to enforce randomness in the circuit, but the > R values would be used to hide their circuit from relays as usual. > > Creating the onion, the user would put a different R value > into each layer, encrypted for that relay, of course. To create the > circuit, they would take a hash of S+R0 to get the address of the > first relay: > A1 = H(S+R0), and then hash this plus R1 to get the second > relay: A2 = H(H(S+R0)+R1)), and so on. Perhaps I don't understand your suggestion, but how would a hash translate to a relay address? The maximum possible strength of a hash is related to the size of its address space, if this is limited to the number of relays available, it would be pretty weak. I would imagine that an 8 bit cpu is likely to be able to easily run through enough hash input combinations to get the address of any tor relay in the network, wouldn't they? -Martin *********************************************************************** To unsubscribe, send an e-mail to majord...@torproject.org with unsubscribe or-talk in the body. http://archives.seul.org/or/talk/