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SUMMARY:Cryptography with Work-based Corruptions and the Combinatorics of 
 Anonymity - Kiayias\, A (Athens)
DTSTART:20120201T110000Z
DTEND:20120201T114500Z
UID:TALK36099@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:In the setting of cryptographic protocols\, the corruption of 
 a party has been viewed as a simple\, uniform and atomic operation\, where
  the adversary decides to get control over a party and this party immediat
 ely gets corrupted.  In this talk\, motivated by the fact that different p
 layers may require different resources to get corrupted\, we introduce the
  notion of  resource-based corruptions\, where the adversary must invest s
 ome resources in order to perform corruptions. If the  adversary has  full
  information about the system configuration then resource-based corruption
 s would provide no fundamental difference from the standard corruption mod
 el. However\, in the `anonymous' setting (where anonymity is in the sense 
 that such configuration  is hidden from the adversary)\, much is to be gai
 ned in terms of efficiency and security. We showcase the power of anonymit
 y in the setting of secure multiparty computation with resource-based corr
 uptions and prove that anonymity can effectively be used to circumvent imp
 ossibility results. Regarding efficiency gains\, we show that anonymity ca
 n be used to  force the corruption threshold to drop from 1/2 to 1/3\, in 
 turn allowing the use of more efficient cryptographic protocols in various
  settings.  Joint work with Juan Garay\, David Johnson (AT&T)\, Moti Yung 
 (Google).
LOCATION:Seminar Room 1\, Newton Institute
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