[Busec] BUsec: no seminar this week

Sharon Goldberg goldbe at cs.bu.edu
Sun Mar 31 21:25:18 EDT 2013


There will be no seminar tomorrow.

There is a security talk in ECE that may be of interest. This Friday at 1PM:


Next week, seminar will be back on, with a talk by our own Omer Paneth.

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

Title: Public-Coin Concurrent Zero-Knowledge in the Global Hash Model
Speaker: Omer Paneth, BU
Monday April 8, 10AM
Public-coin zero-knowledge and concurrent zero-knowledge (cZK) are two
classes of zero
knowledge protocols that guarantee some additional desirable properties.
Still, to this date
no protocol is known that is both public-coin and cZK for a language
outside BPP. Furthermore,
it is known that no such protocol can be black-box ZK [Pass et.al, Crypto
We present a public-coin concurrent ZK protocol for any NP language. The
assumes that all verifiers have access to a globally specified function,
drawn from a collision
resistant hash function family. (This model, which we call the Global Hash
Function, or
GHF model, can be seen as a restricted case of the non-programmable
reference string
model.) We also show that the impossibility of black-box public-coin cZK
extends also to
the GHF model.

Our protocol assumes CRH functions against quasi-polynomial adversaries and
O(log^{1+ \eps}(n)) rounds for any \eps > 0, where n is the security
parameter. Our techniques
combine those for (non-public-coin) black-box cZK with Barak's
non-black-box technique for
public-coin constant-round ZK. As a corollary we obtain the first
simultaneously resettable
zero-knowledge protocol with O(log^{1+ \eps}(n)) rounds, in the GHF model.

Joint work with Ran Canetti and Rachel Lin
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