[guardian-dev] Blackphone

Matej Kovacic matej.kovacic at owca.info
Fri Jan 17 08:27:56 EST 2014


> > Yup, an adversary wiretapping both parties can see that they're
> > communicating. But the parties' OSTN servers can see that _without_
> > wiretapping them.
Not necessarily. They can basically see their phone identity (some
random number), registration e-mail (could also be some fake address),
and IP address.

If NSA is wiretapping OSTN *server*, they can see IP addresses and
amount of data for all callers.

> > Sounds like a good solution, as long as the OSTN accounts are
> > registered and used always through Tor.
Yes. However, as I said, real-time VoIP conversations through Tor are
not really usable. Except voice messages through XMPP, which are
basically files recorded on one side, sent through XMPP/Tor and played
on the other.

But if this XMPP server has .onion address only, it is possible to
connect to it through Tor only.

> > the Tor->Alice direction of the Alice->Tor connection, and the
> > Tor->Bob direction of the Tor->Bob connection, could still be
> > correlated. And of course, circuit setup and teardown times are quite
> > revealing even if the circuits are fully padded.
Hmm, one solution would be to use some bidirectional file transfer
simultaneously. Or... maybe some padding could be implemented in ChatSecure?



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