Directory Authority
Directory Authorities are a small, well-known group of servers that sign the consensus on valid relays. Clients use this consensus to know the network.
Directory authorities are the small set of publicly known servers — currently nine, run by independent, documented operators — that measure the Tor relay population and sign the network consensus. Once per hour they vote on which relays exist, what flags each carries, and how much bandwidth each contributes; the majority view becomes the consensus document every client downloads before building circuits.
Why they matter
They are the network’s trust anchor. Without an agreed relay list, an attacker could feed a victim a fake view of the network and steer them onto malicious relays. Because the authorities are few and known, compromising a majority of them is one of the few structural attacks on Tor’s directory layer — which is why their operators and hosting are deliberately diverse.
Common mistake
Authorities see relay descriptors, not user traffic. They cannot deanonymize connections; that would require observing the path itself, as in a correlation attack. Their power is over the map of the network, not over what flows across it.
Category: Network