Client-server concurrent zero knowledge with constant rounds and guaranteed complexity

Ran Canetti, Abhishek Jain, Omer Paneth

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

The traditional setting for concurrent zero knowledge considers a server that proves a statement in zero-knowledge to multiple clients in multiple concurrent sessions, where the server's actions in a session are independent of all other sessions. Persiano and Visconti [ICALP 05] show how keeping a limited amount of global state across sessions allows the server to significantly reduce the overall complexity while retaining the ability to interact concurrently with an unbounded number of clients. Specifically, they show a protocol that has only slightly super-constant number of rounds; however the communication complexity in each session of their protocol depends on the number of other sessions and has no a-priori bound. This has the drawback that the client has no way to know in advance the amount of resources required for completing a session of the protocol up to the moment where the session is completed. We show a protocol that does not have this drawback. Specifically, in our protocol the client obtains a bound on the communication complexity of each session at the start of the session. Additionally the protocol is constant-rounds. Our protocols is fully concurrent, and assumes only collision-resistant hash functions. The proof requires considerably different techniques than those of Persiano and Visconti. Our main technical tool is an adaptation of the "committed-simulator" technique of Deng et. al [FOCS 09].

Original languageEnglish
Title of host publicationAdvances in Cryptology, CRYPTO 2014 - 34th Annual Cryptology Conference, Proceedings
PublisherSpringer Verlag
Pages337-350
Number of pages14
EditionPART 2
ISBN (Print)9783662443804
DOIs
StatePublished - 2014
Event34rd Annual International Cryptology Conference, CRYPTO 2014 - Santa Barbara, CA, United States
Duration: 17 Aug 201421 Aug 2014

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
NumberPART 2
Volume8617 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference34rd Annual International Cryptology Conference, CRYPTO 2014
Country/TerritoryUnited States
CitySanta Barbara, CA
Period17/08/1421/08/14

Funding

FundersFunder number
National Science Foundation
National Science Foundation1218461

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