[Busec] busec today: Muthu Venkitasubramaniam (Thurs 11am @ CS137)

Sharon Goldberg goldbe at cs.bu.edu
Thu Apr 17 07:00:33 EDT 2014

This week we have a talk about concurrent computation by Muthu
Venkitasubramaniam from the University of Rochester. The talk will be at an
*unusual time*, Thursday at 11am, at CS137 followed by lunch.

See you there!


Adaptive and Concurrent Secure Computation from New Adaptive,
Non-Malleable Commitments
Muthu Venkitasubramaniam
University of Rochester.
Thursday April 17, 2014

We present a unified approach for obtaining general secure computation
that achieves adaptive-Universally Composable (UC)-security.
Conceptually, our approach can be viewed as an adaptive analogue to the
recent work of Lin, Pass and Venkitasubramaniam [STOC ‘09], who
considered only static (i.e. non-adaptive) adversaries. Their main
insight was that the non-malleability requirement could be decoupled
from the simulation requirement to achieve UC-security. A main
conceptual contribution of this work is, quite surprisingly, that it is
still the case even when considering adaptive security. Using our
approach we essentially obtain all previous results on adaptive
concurrent secure computation, both in relaxed models (e.g.,
quasi-polynomial time simulation), as well as trusted setup models
(e.g., the CRS model, the imperfect CRS model). As a corollary we also
obtain the first adaptively secure multiparty computation protocol in
the plain model that is secure under bounded-concurrency.

A key element in our construction is a commitment scheme that satisfies
a strong definition of non- malleability. Our new primitive of
concurrent equivocal non-malleable commitments, intuitively, guarantees
that even when a man-in-the-middle adversary observes concurrent
equivocal commitments and decommitments, the binding property of the
commitments continues to hold for commitments made by the adversary.
This definition is stronger than previous ones, and may be of
independent interest. Previous constructions that satisfy our definition
have been constructed in setup models, but either re- quire existence of
stronger encryption schemes such as CCA-secure encryption or require
independent “trapdoors” provided by the setup for every pair of parties to
ensure non-malleability. A main technical contribution of this work is to
provide a construction that eliminates these requirements and requires only
a single trapdoor.


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Sharon Goldberg
Computer Science, Boston University
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