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SUMMARY:Censorship Circumvention: Staying Ahead in a Cat-and-Mouse Game - 
 Nikita Borisov\, University of Illinois at Urbana-Champaign
DTSTART:20130829T150000Z
DTEND:20130829T160000Z
UID:TALK46863@talks.cam.ac.uk
CONTACT:Microsoft Research Cambridge Talks Admins
DESCRIPTION:The Internet enables access to a wide variety of information s
 ources\; many countries and organizations\, however\, try to restrict such
  access for political and social reasons. People whose access has been cen
 sored make use of a variety of circumvention technologies to find the info
 rmation they need\; in turn\, the censors use increasingly sophisticated t
 ools to render these technologies ineffective. One of the most powerful te
 chniques available to the censors has been the insider attack\, wherein th
 e censor pretends to be a user of a system in order to learn secret inform
 ation about its functions. For example\, censors continually update a blac
 klist of IP addresses belonging to circumvention proxies. I will discuss s
 ome new techniques designed specifically resist this insider threat.\n\nrB
 ridge focuses on the distribution of proxy addresses to users. It tracks t
 he reputation score of each user\, representing the likelihood of this use
 r revealing a proxy address to the censors\, and uses an introduction mech
 anism to resist Sybil attacks. A particular challenge of rBridge is to pre
 serve the privacy of its users by keeping the knowledge about which users 
 know which proxies secret.\n\nCirripede is an alternate approach that seek
 s to eliminate the insider threat entirely. It uses redirection proxies th
 at are activated by a special cryptographic signal\, which can be generate
 d using only public information but can only be recognized by the proxies.
  Instead of hiding the location of the proxies\, Cirripede places them in 
 highly connected ISPs\, such that blocking Cirripede would result in high 
 collateral damage.\n\n
LOCATION:Auditorium\, Microsoft Research Ltd\, 21 Station Road\, Cambridge
 \, CB1 2FB
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