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Re: [tor-talk] TOR Fone - p2p secure and anonymous VoIP tool

On Sun, Feb 3, 2013 at 12:46 PM, Fabio Pietrosanti (naif)
<lists@xxxxxxxxxxxxxxx> wrote:
> ...
> To work over high latency (and tipically also low-bandwidth) with
> reliable transport (like TCP/Tor) you need to use those multimedia strategy:
> - setup a large static jitter buffer (you define the added artificial
> latency of the call to compensate variable latency)
> - reduce transport protocol overhead by setting a large "packetization time"
> - detect retransmission behaviours, in that case apply small TX cutting
> (transmission)

presence and connection signaling is a problem too; also requiring
customization / enhancements to the signalling and transport layers
around these mechanisms, in addition to the voice transport and
implementations details you mention above (which also apply to
multi-media, were you to extend the ZRTP / Tor'ified streams to video
and extended media).

large static jitter buffers also need more help, as a Tor circuit has
a much larger total delay in addition to jitter variance. smarter
dynamic jitter buffers, noise cancelation / silence optimization /
other expensive processing options are useful and applicable, as
anything running a Tor client has plenty of processing power for voice
of any complexity.

regarding the directory and signalling, i would love to test:
- petname or distributed directory (namecoin) for people to hidden
server address(es)
- custom Tor controller to establish and advertise multiple hidden
service endpoints concurrently via different rendz.
- custom SIP/signalling extensions to advertise and register via
ordered hidden svz addresses (maybe just transparent DNS with multiple
peers in RRs?)
- long-lived-ports modified for circuit availability, consistency over
absolute duration?

with the transport and voice processing improvements discussed above.

> With such approach you can avoid "PTT" and even if the communication
> will sounds like an old analog satellite connection, it works.

PTT is orthogonal to the transport question, perhaps limited to some
context like group / conference / broadcast idioms. i agree it may not
be necessary.

best regards,
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