[OTR-users] Is Encryption Limited to Text?

[Ian Goldberg]

On Mon, Mar 19, 2007 at 11:59:35AM +0900, Stephen Perdue wrote:
> Greetings all,
> 
> Forgive what may seem a too obvious question.  I read the OTR web  
> page top to bottom, browsed the last year of the list archive, and  
> scanned the less technical parts of the "Why Not To Use PGP" paper.
> 
> Can OTR handle any data that's passed through it (e.g. video chat,  
> file transfer), or is it limited specifically to text chat?
> 
> The envisioned scenario is iChat + OTR proxy on an Intel MacBook at  
> one end and Trillian Pro + OTR plug-in on WinXP at the other, but I'd  
> welcome any insights outside those conditions as well.

At this time, OTR only protects your IM messages, not video or file
transfer.  I believe Paul's trying to get someone to work on file
transfer, but I don't know of anyone working on video.  The same
mechanism (use OTR to generate session keys, and encrypt/MAC with them,
publish the MAC key later) would work for both; you may want to rotate
keys now and again for a long video chat.  But I have no idea what the
video chat API looks like, since AFAIK, gaim doesn't support it yet.

> While I'm at it, it looks two people have reported issues running OTR  
> Proxy on Intel MacBooks.  Has anyone else had issues?  Can anyone  
> report smooth operation?

Some people reported that the Motorola code had issues on Intel machines
under emulation, but others found it fine.  Somebody posted a link to a
native Intel binary, though, if I remember correctly.

> If OTR is not suitable, any other suggestions for reasonably private  
> video chat?  (I use Skype now but find it a bit flakey.)  I have no  
> expectation of selective attack, just everyday privacy concerns.  I  
> can live without deniability/forgeability since I'm certainly beneath  
> the interest of anyone with the resources to convincingly forge video.

Back In The Day (the 90's), I used vic for video chat, which supported
at least some encryption (DES at the time).  I bet you'd be hard-pressed
to get it to still work today, though.

   - Ian