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> I also do not think their claims of Tor subversion hold water. From what I understand of Tor, directory information (including nodes' key fingerprints) is ult

> I also do not think their claims of Tor subversion hold water. From what I understand of Tor, directory information (including nodes' key fingerprints) is ultimately verified by the hard-coded keys of very few "trusted" operators of authoritative directory servers. I'm very fascinated by this. Do you have any links to a faq/technical entry that focuses on these directory servers and their application?

kyboren 13y ago
I do not know about a FAQ, but this document describes what I mentioned: https://gitweb.torproject.org/torspec.git?a=blob_plain;hb=HEAD;f=dir-spec.txt https://gitweb.torproject.org/torspec.git?a=blob_plain;hb=HE... (read the section "1. Outline"). There is a small set (say, around 5-10) of semi-trusted directory authorities. A default list of authorities is shipped with the Tor software. Users can change this list, but are encouraged not to do so, in order to avoid partitioning attacks. Every authority has a very-secret, long-term "Authority Identity Key". This is stored encrypted and/or offline, and is used to sign "key certificate" documents. Every key certificate contains a medium-term (3-12 months) "authority signing key", that is used by the authority to sign other directory information. (Note that the authority identity key is distinct from the router identity key that the authority uses in its role as an ordinary router.) Routers periodically upload signed "routers descriptors" to the directory authorities describing their keys, capabilities, and other information. Routers may also upload signed "extra info documents" containing information that is not required for the Tor protocol. Directory authorities serve router descriptors indexed by router identity, or by hash of the descriptor. Routers may act as directory caches to reduce load on the directory authorities. They announce this in their descriptors. Periodically, each directory authority generates a view of the current descriptors and status for known routers. They send a signed summary of this view (a "status vote") to the other authorities. The authorities compute the result of this vote, and sign a "consensus status" document containing the result of the vote. Directory caches download, cache, and re-serve consensus documents. Clients, directory caches, and directory authorities all use consensus documents to find out when their list of routers is out-of-date. (Directory authorities also use vote statuses.) If it is, they download any missing router descriptors. Clients download missing descriptors from caches; caches and authorities download from authorities. Descriptors are downloaded by the hash of the descriptor, not by the relay's identity key: this prevents directory servers from attacking clients by giving them descriptors nobody else uses.

kyboren 13y ago

I do not know about a FAQ, but this document describes what I mentioned: https://gitweb.torproject.org/torspec.git?a=blob_plain;hb=HEAD;f=dir-spec.txt https://gitweb.torproject.org/torspec.git?a=blob_plain;hb=HE... (read the section "1. Outline"). There is a small set (say, around 5-10) of semi-trusted directory authorities. A default list of authorities is shipped with the Tor software. Users can change this list, but are encouraged not to do so, in order to avoid partitioning attacks. Every authority has a very-secret, long-term "Authority Identity Key". This is stored encrypted and/or offline, and is used to sign "key certificate" documents. Every key certificate contains a medium-term (3-12 months) "authority signing key", that is used by the authority to sign other directory information. (Note that the authority identity key is distinct from the router identity key that the authority uses in its role as an ordinary router.) Routers periodically upload signed "routers descriptors" to the directory authorities describing their keys, capabilities, and other information. Routers may also upload signed "extra info documents" containing information that is not required for the Tor protocol. Directory authorities serve router descriptors indexed by router identity, or by hash of the descriptor. Routers may act as directory caches to reduce load on the directory authorities. They announce this in their descriptors. Periodically, each directory authority generates a view of the current descriptors and status for known routers. They send a signed summary of this view (a "status vote") to the other authorities. The authorities compute the result of this vote, and sign a "consensus status" document containing the result of the vote. Directory caches download, cache, and re-serve consensus documents. Clients, directory caches, and directory authorities all use consensus documents to find out when their list of routers is out-of-date. (Directory authorities also use vote statuses.) If it is, they download any missing router descriptors. Clients download missing descriptors from caches; caches and authorities download from authorities. Descriptors are downloaded by the hash of the descriptor, not by the relay's identity key: this prevents directory servers from attacking clients by giving them descriptors nobody else uses.