[Busec] BUsec this week: Mohammad Mahmoody (Wed 10AM)

Sharon Goldberg goldbe at cs.bu.edu
Tue Nov 13 09:28:13 EST 2012


A reminder for tomorrow's seminar at 10AM, where Mohammad Mahmoody from
Cornell will be discussing tamper resilient cryptography.  We meet at the
Harriri Institute (note different room!) on the first floor of 111
Cummington St.

Abstracts below.  See you tomorrow!


BUsec Calendar:  http://www.bu.edu/cs/busec/
BUsec Mailing list:  http://cs-mailman.bu.edu/mailman/listinfo/busec


On the (Im)Possibility of Tamper-Resilient Cryptography
Using Fourier Analysis in Computer Viruses
Mohammad Mahmoody, Cornell.
Wed Nov 14, 2012 10AM

We initiate a study of the security of cryptographic primitives in the
presence of efficient tampering attacks to the randomness of honest
parties. More precisely, we consider p-tampering attackers that may
tamper with each bit of the honest parties' random tape with
probability p, but have to do so in an "online" fashion. We present
both positive and negative results:

* Any secure encryption scheme, bit commitment scheme, or zero-
knowledge protocol can be “broken” with probability p by a p-tampering
The core of this result is a new Fourier analytic technique for
biasing the output of bounded-value functions, which may be of
independent interest (and provides an alternative, and in our eyes
simpler, proof of the classic Santha-Vazirani theorem).

* Assuming the existence of one-way functions, cryptographic
primitives such as signatures, identification protocols can be made
resilient to p-tampering attacks for any p = 1/n^{\alpha}, where
\alpha > 0 and n is the security parameter.

Joint work with Per Austrin, Kai-Min Chung, Rafael Pass, and Karn Seth

Sharon Goldberg
Computer Science, Boston University
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