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Efficient CCA Timed Commitments in Class Groups

hal.structure.identifierFriedrich-Alexander Universität Erlangen-Nürnberg = University of Erlangen-Nuremberg [FAU]
dc.contributor.authorTHYAGARAJAN, Sri
hal.structure.identifierLithe and fast algorithmic number theory [LFANT]
dc.contributor.authorCASTAGNOS, Guilhem
hal.structure.identifierExact Computing [ECO]
dc.contributor.authorLAGUILLAUMIE, Fabien
hal.structure.identifierMax Planck Institute for Security and Privacy [Bochum] [MPI SP]
dc.contributor.authorMALAVOLTA, Giulio
dc.date.accessioned2024-04-04T02:43:40Z
dc.date.available2024-04-04T02:43:40Z
dc.date.issued2021-11-12
dc.date.conference2021-11-15
dc.identifier.urihttps://oskar-bordeaux.fr/handle/20.500.12278/191348
dc.description.abstractEnTimed commitments [Boneh and Naor, CRYPTO 2000] are the timed analogue of standard commitments, where the commitment can be non-interactively opened after a pre-specified amount of time passes. Timed commitments have a large spectrum of applications, such as sealed bid auctions, fair contract signing, fair multi-party computation, and cryptocurrency payments. Unfortunately, all practical constructions rely on a (private-coin) trusted setup and do not scale well with the number of participants. These are two severe limiting factors that have hindered the widespread adoption of this primitive. In this work, we set out to resolve these two issues and propose an efficient timed commitment scheme that also satisfies the strong notion of CCA-security. Specifically, our scheme has a transparent (i.e. public-coin) one-time setup and the amount of sequential computation is essentially independent of the number of participants. As a key technical ingredient, we propose the first (linearly) homomorphic time-lock puzzle with a transparent setup, from class groups of imaginary quadratic order. To demonstrate the applicability of our scheme, we use it to construct a new distributed randomness generation protocol, where parties jointly sample a random string. Our protocol is the first to simultaneously achieve (1) high scalability in the number of participants, (2) transparent one-time setup, (3) lightning speed in the optimistic case where all parties are honest, and (4) ensure that the output random string is unpredictable and unbiased, even when the adversary corrupts − 1 parties. To substantiate the practicality of our approach, we implemented our protocol and our experimental evaluation shows that it is fast enough to be used in practice. We also evaluated a heuristic version of the protocol that is at least 3 orders of magnitude more efficient both in terms of communication size and computation time. This makes the protocol suitable for supporting hundreds of participants.
dc.description.sponsorshipAppLicAtions de la MalléaBIlité en Cryptographie - ANR-16-CE39-0006
dc.language.isoen
dc.title.enEfficient CCA Timed Commitments in Class Groups
dc.typeCommunication dans un congrès
dc.identifier.doi10.1145/3460120.3484773
dc.subject.halInformatique [cs]/Cryptographie et sécurité [cs.CR]
bordeaux.page2663-2684
bordeaux.hal.laboratoriesInstitut de Mathématiques de Bordeaux (IMB) - UMR 5251*
bordeaux.institutionUniversité de Bordeaux
bordeaux.institutionBordeaux INP
bordeaux.institutionCNRS
bordeaux.conference.titleCCS 2021 - ACM SIGSAC Conference on Computer and Communications Security
bordeaux.countryKR
bordeaux.conference.citySeoul (online)
bordeaux.peerReviewedoui
hal.identifierhal-03466495
hal.version1
hal.invitednon
hal.proceedingsoui
hal.conference.end2021-11-19
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-03466495v1
bordeaux.COinSctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.date=2021-11-12&rft.spage=2663-2684&rft.epage=2663-2684&rft.au=THYAGARAJAN,%20Sri&CASTAGNOS,%20Guilhem&LAGUILLAUMIE,%20Fabien&MALAVOLTA,%20Giulio&rft.genre=unknown


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