[OTR-dev] PoC implementation of "Deniable Group Key Agreement" protocol from Bohli et al. (mpOTR)

[George Kadianakis]

Some time ago I started hacking an implementation of the protocol
described in the "Deniable Group Key Agreement" paper by Bohli and
Steinwandt. I mainly did it because I wanted to write some crypto code
and because I wanted to experiment with the protocol.

The protocol looks useful in the mpOTR setting since it allows
multiple participants to do a key-exchange and authenticate to each
other in a "deniable" way. Matthew Van Gundy used this protocol in his
"Improved Deniable Signature Key Exchange for mpOTR" paper.

The implementation is in Go and works like a simulation. It simulates
a number of participants and does a protocol run between them. In the
end it outputs whether the authentication was successful and the
shared secret between them. You can find it here:
https://github.com/asn-the-goblin-slayer/bohli_simulation

I'm posting it here because someone might find it useful and it's
probably better than letting it rot in my hard drive. Better keep the
code flowing.

I also heard that Nadim is setting up an mpOTR research team, so my
plan is to stop playing with Bohli's protocol till some results appear
from the mpOTR team.

Cheers!

PS: Talking about multiparty key-exchange/authentication protocols, I
    want to find some time to research how Trevor Perrin's protocol
    from https://whispersystems.org/blog/simplifying-otr-deniability/
    would perform in a multiparty setting (each user creates three DH
    shared-secrets with each of the other participants and uses all of
    them in a KDF seed).