[OTR-users] diffie-hellyes

[Len Sassaman]

On Wed, 22 Jun 2005, CLAY SHENTRUP wrote:

> I think the next step on this plug-in, and I wish I had the time
> to help, would be to make the equivalent of mixminion for IM.
> Essentially, your message is encrypted like those little Russian
> dolls, so that the next person in the line can encrypt a layer,
> and then on down the line, until the final party can view the
> message, and an outside observer would be hard pressed to
> discover who you were talking to.  Maybe this is too process
> intensive, since it would require successive RSA decryption to
> peel away the layers, as well as the permission of various
> people on a network.  Just a thought..

Building strong anonymity into IM systems is a very difficult proposition.
Unlike email, where it isn't a huge problem if messages are delivered with
high latency and in a different order than when they are sent, IM systems
generally want extremely low latency and synchronous delivery.

But worse, most IM systems are centrally operated by private entities,
which would make either traffic analysis or blocking of the anonymous IM
servers trivial.

There are other alternatives, such as using Tor with a dedicated IM screen
name (which would have to be created, and used exclusively with Tor, lest
an attacker learn a real ID to associate with the name). Tor, however,
provides much less anonymity than high-latency systems like Mixmaster and
Mixminion, as a trade-off for its low-latency properties.

I predict we won't see a decent IM anonymity solution until we solve the
low-latency anonymity problems, have wide-spread use of decentralized IM
systems, or both.


--Len.