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SUMMARY:Hot or Not: Revealing Hidden Services by their Clock Skew - Steven
  J. Murdoch (Computer Laboratory\, University of Cambridge)
DTSTART:20061027T150000Z
DTEND:20061027T153000Z
UID:TALK5798@talks.cam.ac.uk
CONTACT:Steven J. Murdoch
DESCRIPTION:Location-hidden services\, as offered by anonymity systems suc
 h as Tor\, allow servers to be operated under a pseudonym. As Tor is an ov
 erlay network\, servers hosting hidden services are accessible both direct
 ly and over the anonymous channel. Traffic patterns through one channel ha
 ve observable effects on the other\, thus allowing a service's pseudonymou
 s identity and IP address to be linked. One proposed solution to this vuln
 erability is for Tor nodes to provide fixed quality of service to each con
 nection\, regardless of other traffic\, thus reducing capacity but resisti
 ng such interference attacks. However\, even if each connection does not i
 nfluence the others\, total throughput would still affect the load on the 
 CPU\, and thus its heat output. Unfortunately for anonymity\, the result o
 f temperature on clock skew can be remotely detected through observing tim
 estamps. This attack works because existing abstract models of anonymity-n
 etwork nodes do not take into account the inevitable imperfections of the 
 hardware they run on. Furthermore\, we suggest the same technique could be
  exploited as a classical covert channel and can even provide geolocation.
LOCATION:Computer Laboratory\, William Gates Building\, Room FW11
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