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Tue Mar 1 03:41:44 UTC 2011


taking up 37 bytes) and 884 non-empty ones. If we dropped the empty
ones we would save about 4% of network traffic. It's not huge, but not
trivial either.

We would save even more if we could coalesce more cells per packet and
application record (currently 72% of non-empty application records
have one cell and 81% of packets have one cell or less).

I am not sure why empty application records are being sent. It is a
good idea to send one at the start, to prevent an attack (see point 2 of
http://www.openssl.org/~bodo/tls-cbc.txt). Maybe we're seeing the
empty application records as a side-effect of this countermeasure.

The data can be seen here:
 http://www.cl.cam.ac.uk/~sjm217/volatile/tor-patches/log-keys/testrun4/
 http://www.cl.cam.ac.uk/~sjm217/volatile/tor-patches/log-keys/testrun5/

testrun4 and testrun5 are the two runs. The Tor log files are there
(debug.log and info.log), the tcpdump file (packet.dump), and the
decrypted TLS application record listing (decoded.txt).

Does anyone have ideas on how to remove the redundant TLS application
records, or otherwise improve the efficiency?

Steven.

-- 
w: http://www.cl.cam.ac.uk/users/sjm217/



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