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On Concurrent Zero-Knowledge with Pre-Processing
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Giovanni Di Crescenzo and Rafail Ostrovsky
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Abstract:
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Concurrent Zero-Knowledge protocols remain zero-knowledge even when
many sessions of them are executed together. These protocols have
applications in a distributed setting, where many executions of the
same protocol must take place at the same time by many parties, such
as the Internet. In this paper, we are concerned with the number of
rounds of interaction needed for such protocols and their efficiency.
Here, we show an efficient constant-round concurrent zero-knowledge
protocol with preprocessing for all languages in NP, where both the
preprocessing phase and the proof phase each require 3 rounds of
interaction. We make no timing assumptions or assumptions on the
knowledge of the number of parties in the system. Moreover, we allow
arbitrary interleavings in both the preprocessing and in the proof
phase. Our techniques apply to both zero-knowledge proof systems and
zero-knowledge arguments and we show how to extend our technique so
that polynomial number of zero-knowledge proofs/arguments can be
executed after the preprocessing phase is done.

**comment:**
Appeared in Proceedings
of Advances in Cryptology (CRYPT0-99), pp. 485-502,
Springer-Verlag
Lecture Notes in Computer Science, Vol 1666.

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