[OTR-users] mpOTR Scalability

Christoph A. casmls at gmail.com
Tue Sep 7 10:24:03 EDT 2010


Hi,

do you have some raw figures how well mpOTR will scale?

As the setup phase contains steps that need to be done in a pairwise
fashion I'm focusing on the scalability of this phase and the DSKE().

Given n participants the total amount of AuthUser() executions for all
users together is n*(n-1)/2
(Depending on your view and definition of AutUser() "/2" is discussable.)

An important property is that AuthUser() is non-blocking and Alice can
execute multiple instances of them in parallel to reduce total amount of
time spent for DSKE().

Alice doesn't need to wait until AuthUser(Bob) is finished before she
can start AuthUser(Charlie).

Did you make some raw estimates (or requirements) when designing mpOTR?

For example something like: "The Setup-Phase in a room with 10
participants will take ~22 seconds, given recent notebooks and an
average network latency of 60 miliseconds".

The time spent for the generation of the ephemeral signing key might
also be a considerable part of the setup-phase.

It would be interesting to hear from you (mpOTR designers).

kind regards,
Christoph
--
example for 10 participants:
10*9/2 = 45 AuthUser() instances
AuthUser() generates 4 packets (without denAKE())
45x4=180 packets in total
36packets per participant (18 sending + 18 receiving)
...but I don't know the size of such packets.


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