tor/doc/spec/proposals/123-autonaming.txt

Filename: 123-autonaming.txt
Title: Naming authorities automatically create bindings
Version: $Revision$
Last-Modified: $Date$
Author: Peter Palfrader
Created: 2007-10-11
Status: Finished

Overview:

  Tor's directory authorities can give certain servers a "Named" flag
  in the network-status entry, when they want to bind that nickname to
  that identity key. This allows clients to specify a nickname rather
  than an identity fingerprint and still be certain they're getting the
  "right" server.

  Authority operators name a server by adding their nickname and
  identity fingerprint to the 'approved-routers' file.  Historically
  being listed in the file was required for a router, at first for being
  listed in the directory at all, and later in order to be used by
  clients as a first or last hop of a circuit.

  Adding identities to the list of named routers so far has been a
  manual, time consuming, and boring job.  Given that and the fact that
  the Tor network works just fine without named routers the last
  authority to keep a current binding list stopped updating it well over
  half a year ago.

  Naming, if it were done, would serve a useful purpose however in that
  users can have a reasonable expectation that the exit server Bob they
  are using in their http://www.google.com.bob.exit/ URL is the same
  Bob every time.

Proposal:
  I propose that identity<->name binding be completely automated:

  New bindings should be added after the router has been around for a
  bit and their name has not been used by other routers, similarly names
  that have not appeared on the network for a long time should be freed
  in case a new router wants to use it.

  The following rules are suggested:
  i) If a named router has not been online for half a year, the
     identity<->name binding for that name is removed.  The nickname
     is free to be taken by other routers now.
  ii) If a router claims a certain nickname and
       a) has been on the network for at least two weeks, and
       b) that nickname is not yet linked to a different router, and
       c) no other router has wanted that nickname in the last month,
      a new binding should be created for this router and its desired
      nickname.

 This automaton does not necessarily need to live in the Tor code, it
 can do its job just as well when it's an external tool.