[OTR-users] mpOTR Scalability

[Christoph A.]

On 09/08/2010 02:08 PM, Ian Goldberg wrote:
>> 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".
> No, the design didn't have requirements like that.
> 
>> > The time spent for the generation of the ephemeral signing key might
>> > also be a considerable part of the setup-phase.
> I don't know why this would necessarily be.  For any DL-based signature
> scheme, for example, key generation is one modexp.  (Current OTR uses
> DSS, which has this property.)  Only for RSA-based schemes is key
> generation slow.
> 
>> > 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.
> In practice, the size of the packets will be less of a problem than the
> rate-limiting that some IM networks impose.  On those networks, one will
> have to be very careful about how fast the messages are sent.
> 
> Also important is the number of rounds of communication: being able to
> blast out 18 messages and wait for their responses is different from
> exchanging 18 messages and responses one at a time.

Thank you for your input!
Christoph


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