4 ms·
Surely the sudden spike in entry and exit nodes would make the attack obvious. The central directory authority service could be modified to blacklist nodes from
by s_q_b 13y ago
Surely the sudden spike in entry and exit nodes would make the attack obvious. The central directory authority service could be modified to blacklist nodes from the master OR directory list that join within too small of a time interval.
On a more practical note, few cloud providers are going to let their network suddenly become a massive transit space for Tor traffic.
Before this could be successfully deployed in the wild, the problem can be easily corrected.
- D9u 13y agoBut the NSA could easily add a few hundred Tor nodes given their capabilities regarding hundreds of Linux cloud servers as part of XKeyScore et al.
- s_q_b 13y agoA few hundred Tor nodes would be useless in trying to break anyone's anonymity. With ~4k relays (entry/exits) and ~2k bridges (pure relays of encrypted connections) and only a few hundred hostile relays, the odds of an OP's (end-user's) connection's flowing through both a hostile entry node and a hostile exit node are infinitesimal. Let's say you add 400 ORs to the network. Let's further assume no one in the privacy-conscious, some would say paranoid, Tor community notices this unexplained 10% spike in entry/exit nodes. Your odds of compromising any given Tor circuit (connection) are a compound probability: P(A and B) = P(A) * P(B). In this case: .1 * .1 = .01, or approximately 1%. When you add to the fact that the network automatically tries to route to entry and exit nodes in different countries, the chances of compromising the network in this fashion are virtually nill. Everyone in the Tor community has known this attack has been possible, which is why the network growth metrics are watched closely. If any shenanigans are detected, the authority is prepared to add a notion of OR trust to the directory file.