VoIP, Tor and Zfone by Phillip Zimmermann?

Michael Holstein michael.holstein at csuohio.edu
Tue May 16 15:04:13 UTC 2006

The latency would make the call entirely unworkable.


Anothony Georgeo wrote:
> Good day,
> I was thinking of routing a VoIP call (SIP protocol)
> via. a VoIP client into Phillip Zimmermann's new
> "Zfone" (
> http://www.philzimmermann.com/EN/zfone/index.html )and
> then into Tor before the VoIP call reaches the other
> party(s).
> One problem I see is that most VoIP clients use UDP (I
> think) and so does Zfone.  But, Zfone has a proxy
> configuration window (I think) which may route into
> TCP/IP.  I only have a windows box and the Windows
> Zfone isn't released yet.
> I was thinking of routing a VoIP call via. a VoIP
> clinet into Zfone (port 5060) then into Tor (via.
> Torcap with Zfone).  Does Torcap do UDP to TCP/IP?
> Another idea is to communicate with other parties via.
> Tor's Hidden Services(HS).  Can HS be configured to
> route a VoIP call?  Could a HS .onion address is used
> inplace of the other parties VoIP number in a VoIP
> clinet?
> Does anyone know of a good, open-source and free VoIP
> clinet for Windows XP/NT?
> -Slighlty off topic-
> What the Tor community really needs is a "UDP to
> TCP/IP" library for Tor (if that's even possible). 
> This way UDP protocol specific programs could be used
> with Tor.  I know "TCP/IP to UDP" library is possbile
> as UDP is the underlying protocol for TCP/IP (I
> think).
> -Back to topic-
> Zfone runs in the IP stack and detects a VoIP call
> when it starts.  Zfone then captures, secures (eg.
> authenticates) and encrypts all VoIP packets 'on the
> fly'.  Zfone creates an end-to-end tunnel to other
> Zfone users via. TLS and it also uses DH key
> agrements.  Zfone also offers defense from MiTH
> attacks via. a short authentication code that appears
> in all parties Zfone GUI to be read over the phone for
> verification.
> Any opinions, thoughts?
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