Filename: xxx-onion-nyms.txt
Title: .onion nym system
Author: Arturo Filastò, Jacob Appelbaum
Created: 17 December 2011
Status: Draft

1. Intro and Motivation

  The main issue that prohibits the wide scale adoption of .onion addressing
  is the fact that they are not human memorable. While Zooko's triangle says that
  you can only have at most two of "memorable", "secure" and "global" it is
  possible to build a simple nym mechanism that relies on the current .onion
  addressing system.  We define a basic registration system generally and also
  it's particual application to the tor2web network. This is a very simple kind
  of petname system for applications such as tor2web.

2. Definitions

  These are the definitions of the actors involved in the process.

  Beppe - The owner of the Tor Hidden Service
  User - A random user of Tor/tor2web
  v2cbb2l4lsnpio4q.onion - The .onion address that Beppe is interested in registering
  antani - The nym Beppe is interested in associating to v2cbb2l4lsnpio4q.onion
  t2w - A tor2web node


3. Registration

  This is the process through which Beppe is able to make a registration for his chosen
  nym.

3.1 General implementation

  Beppe wishes to register "antani" to point to v2cbb2l4lsnpio4q.onion so he creates a
  a TCP service listening on his .onion will respond with the string "reg antani" when
  interrogated. The requester will make a lookup in his database to see if
  "antani" is already registered. If it is not registered the "antani" <->
  v2cbb2l4lsnpio4q.onion mapping is created. A timestamp is added to the
  database.

3.2 Tor2web implementation

  Beppe creates a file called "onion.txt" containing the string "reg antani" and uploads
  it to the root of his web server. When User visits v2cbb2l4lsnpio4q.tor2web.org the
  t2w checks if his database contains a mapping with v2cbb2l4lsnpio4q.onion, if it does
  not, it requests the http://v2cbb2l4lsnpio4q.onion/onion.txt file.
  If the file exists t2w reads it and extracts the "antani" string. A lookup is made in
  his database. If "antani" is not registered he creates a mapping between "antani" and
  v2cbb2l4lsnpio4q.onion. A timestamp is added to the database.

4. Expiration

  A nym will expire if either the HS goes offline for longer than a given time
  threshold or if he explicitly requests removal of the association to that
  particualr nym. This allows dynamic reallocation of nyms and avoids nym
  squatting.

4.1 Time delay

  We define the default tiem threshold to be 30 days since the last check. At
  the time of expiry or anytime before, another request is made to either the TCP
  service or for the "onion.txt" file. If the Hidden Service is offline or if
  the requested mapping has changed the mapping is removed or modified.  If the
  onion.txt is unchanged, the nym remains valid and the database timestamp
  entry is updated.

  4.2 Release

  The HS can specify the "release" string to delete the entry from the nym database.

5. Synchronization

  To keep the database of registered nyms up to date in for many t2w nodes, a synchronization
  mechanism is required but currently out of scope for this document.


