= Security Goals =
== Transcript consistency ==
* Recipients are informed of the correct causal order of messages
* Excessively delayed messages are detected
== Nonblocking join ==
* Join and leave are treated as messages, so transcript consistency applies (causal order, delays are detected).
* New users have to "confirm" to existing users to join.
* Existing users have to "confirm" to the new user shortly after the new user joins (e.g. 1 minute).
= General concepts =