[messaging] Proposal for anonymous contact discovery

[Tom Ritter]

On 25 July 2014 10:39, Joseph Bonneau <jbonneau at gmail.com> wrote:
>> But it occurs to me the SMTP message-id approach is not completely
>> sunk because of the assumptions - we just need to open it up to lots
>> more messages.  This problem is essentially trying to perform set
>> intersection.  I have a bunch of 'secret' bitstrings I think you share
>> some of, let's figure out if we do in fact share some. If we do, that
>> bitstring can be used as keying material to authenticate a longer-term
>> key.
>
> I was thinking of the problem a little differently, with it explicitly being
> a one-shot non-interactive protocol using a server because Earl won't be
> online when Layton decides to join. This seems to be a usability constraint
> in the case of people installing a new app on their phone and wanting to
> immediately discover which friends are using the same service (otherwise
> they may drop the app forever).

That's true.  I believe that even though
http://ipsit.bu.edu/documents/ieee-it3-web.pdf is non-interactive, you
must still have done some initial setup with the other party.  I
think.

-tom