[tor-dev] [Stegotorus] Fundamental problem with ack/retransmission mechanism

Vmon vmonmoonshine at gmail.com
Mon Jun 24 03:04:12 UTC 2013

Hey Jeroen,

Thank you and thanks to the little birdy :)

Jeroen Massar <jeroen at massar.ch> writes:

> A little birdy whispered in my ear that a much revised version with a
> lot of new features and various fixes including a lot of
> ack/retransmit
> fixes should come available soon, but it is pending $org
> review... that
> version even works fine on Windows btw.

That is a great news. Does the little birdy also has some news about the
encryption and the handshake, as far as I see in the current source it
is symmetric with hardcoded key while the original design was calling
for a double elliptic curve system ( a curve and its twist). I think
that was a dead important priority. 

> The problem is not about TCP, but more about HTTP where a censor or a
> rate-limitter in general (eg Hotel WiFi tends to have issues) dnnnnnoes not
> always answer every HTTP request and thus one loses
> packets. Retransmit
> is also important in those cases.

That makes the situation more clear and somehow now. When I told  Zack
that retransmission on single connection has problem (it gets stuck) he
told me that he's not sure if we shouldn't do retransmission when we only have single
connection (single TCP connection, like the nosteg module). Clearly in
even such a situation still retransmit is useful if we are fearing proxy intervention.

I'm looking forward to see the new release. Meanwhile, these are some
speed test I did one day after election in Iran (unfortunately ssh was
blacklisted before the election and I didn't have access to my box to run the tests):

connection:            dn/up (mbps)
No proxy:              2.09/2.08
Psiphon:               0.76/0.2 
StegoTorus nosteg:     2.04/0.46*
StegoTorus http:       0.17/0.07


*(obviously this is because of upload limit on my machine) 

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