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<div>This week's MIT QIP seminar will take place on Monday, February
23rd at 16:00 hours in MIT room 4-237, and features:</div>
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<div align="center"><font size="+2"><b>Zero-Knowledge Proofs
Withstanding Quantum Attacks</b></font></div>
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<div align="center"><font size="+1"><i>by</i> Dr. Louis Salvail
(<i>Computer Science, Univ. of Aarhus, Denmark</i>)</font></div>
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<div align="center"><u>ABSTRACT</u></div>
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<blockquote>The concept of zero-knowledge (ZK) proof has become
of fundamental importance in cryptography. However, in a setting where
entities are modeled by quantum computers, classical arguments for
proving ZK fail to hold. Specifically, in the quantum setting, the
concept of rewinding is not generally applicable, and protocols that
are classically proven to be ZK may be insecure. Moreover, known
classical techniques that avoid rewinding have various shortcomings in
the quantum setting.</blockquote>
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<blockquote>In this talk, I shall introduce new techniques for
building zero-knowledge protocols secure against quantum adversaries
(QZK protocols). We will see how to obtain QZK proofs and
perfect QZK arguments for any NP language in the common reference
string model. Underlying this is a general method to convert an
important class of classical honest-verifier ZK (HVZK) proofs into
"quantum" ZK (QZK) proofs that remain secure even under
(active) quantum attacks. This leads to quite practical protocols if
the underlying HVZK proof is efficient.</blockquote>
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<blockquote>As part of the construction, we propose a general
framework for building unconditionally hiding(trapdoor) string
commitment schemes, secure against quantum attacks, as well as
concrete instantiations based on specific (believed to be) hard
problems. This is of independent interest, as these are the first
unconditionally hiding string commitment schemes withstanding quantum
attacks.</blockquote>
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<div>Next week's feature: wim van Dam (CTP/MIT).</div>
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