From the Tor design paper[1] section 5.2: > Location-hidden services use a virtual top level domain called .onion: thus hostnames take the form x.y.onion where

From the Tor design paper[1] section 5.2: > Location-hidden services use a virtual top level domain called .onion: thus hostnames take the form x.y.onion where x is the authorization cookie and y encodes the hash of the public key. [1] https://svn.torproject.org/svn/projects/design-paper/tor-design.html https://svn.torproject.org/svn/projects/design-paper/tor-des...