On 2012-01-18, Nick Mathewson nickm@alum.mit.edu wrote:
On Tue, Jan 17, 2012 at 1:28 PM, Robert Ransom rransom.8774@gmail.com wrote:
With that hack on top of the v3 protocol, any client able to detect that a bridge is not being MITMed can impersonate the bridge through the TLS handshake, until after the (honest, victim) client speaks the Tor protocol at the fake bridge.
Seems mostly harmless; the only point of a shared secret there is to keep scanning from working. Anybody who tries the above attack already know that the bridge is there; all they learn is that the client knew too, which they probably could have figured out as an eavesdropper.
Censoring MITM attackers tend to MITM all SSL/TLS connections, regardless of their destination. No one would benefit from performing a targeted MITM attack on a bridge, even if we implemented bridge passwords in such a way that a MITM attacker can obtain the password needed to connect to (and use) a bridge.
Robert Ransom