[Telepathy] API sketches for encrypted channels, and OTR

[Eric Hopper]

On Mon, Oct 12, 2009 at 05:31:03PM -0400, Will Thompson wrote:
> Hi,
> 
> Here at the Boston Gnome Summit, Sjoerd, Rob and I stood around a
> blackboard drawing pictures[0] of how encrypted channels (using XTLS on
> XMPP, for instance) would look. Vague summary:

Thank you very much for looking at this.

> We then discussed various ways we could implement OTR support in
> Telepathy, ideally using the same API as for XTLS channels:
> 
> 1. Build OTR support into the necessary CMs (Gabble, Butterfly, Haze)
> and implement the same API as for XTLS.

I, for one, think XTLS is potentially a really bad idea.  The security
model of TLS is wrong and unworkable.  Relying on any kind of trusted
central authority to verify identity is a bad way to go.

The ssh model for identity verification works much better.  And that's
the model OTR uses.  Essentially remember the key you used when you
talked to someone and verify they are using the same key when you talk
to them again.  And also provide a convenient way for verification
through a more trusted channel.

I do believe that TLS only uses a MAC for ensuring that every individual
message makes it through unscathed, and so TLS provides a similar level
of deniability to OTR as far as being able to claim the other party made
up the conversation.

I know that this particular message isn't particularly germane to the
internal imeplementation details of how to make OTR work inside of
empathy.  But it is relevant to the question of encryption in empathy as
a whole.

Again, thanks for working on this, it is appreciated,
-- 
Eric Hopper (hopper at omnifarious.org http://www.omnifarious.org/~hopper)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 664 bytes
Desc: not available
Url : http://lists.freedesktop.org/archives/telepathy/attachments/20091109/e44c7da4/attachment.pgp