I asked this question about Tor and how secure are the first steps before the circuit is made (the guy who answered me, lead me to this site which i didn't know).
Please correct me if I'm wrong (or if the guy is wrong, since I will take his answer as starting point).
Currently the Directories (which are hard-coded servers in the Tor software) download a huge list of nodes. The Tor client is the one who creates the circuit. However: How can one be sure that the Directories are not compromised (after all, they are mainly maintained by the US Defense dept.) and don't bring compromised nodes? I'm aware that Tor does not build a circuit having 2+ nodes from the same "person" but ... what if the NSA has spread a lot of nodes and the Directories bring you such nodes? (perhaps your IP address is already being watched by the US dept. for suspicious* activities beforehand, and they only grant you, for that IP, a subset of nodes which are all from distinct identities but all of them compromised in the same way).
How feasible is what I say?
(* this could apply even to entire countries, e.g. USA trying to put an eye on Venezuela, Ecuador, Argentina, Middle-East countries with internet access, ... having a IP2Location database is easy to get and pay for).