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Meeting Tight Security for Multisignatures in the Plain Public Key Model
Naoto YANAI
Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences
Vol.E101A
No.9
pp.14841493 Publication Date: 2018/09/01
Online ISSN: 17451337
DOI: 10.1587/transfun.E101.A.1484
Type of Manuscript: Special Section PAPER (Special Section on Discrete Mathematics and Its Applications) Category: Keyword: multisignatures, plain public key model, provable security, tight reduction, random oracle model, CDH problem,
Full Text: PDF(690.6KB) >>Buy this Article
Summary:
Multisignatures are digital signatures for a group consisting of multiple signers where each signer signs common documents via interaction with its cosigners and the data size of the resultant signatures for the group is independent of the number of signers. In this work, we propose a multisignature scheme, whose security can be tightly reduced to the CDH problem in bilinear groups, in the strongest security model where nothing more is required than that each signer has a public key, i.e., the plain public key model. Loosely speaking, our main idea for a tight reduction is to utilize a threeround interaction in a fulldomain hash construction. Namely, we surmise that a fulldomain hash construction with threeround interaction will become tightly secure under the CDH problem. In addition, we show that the existing scheme by Zhou et al. (ISC 2011) can be improved to a construction with a tight security reduction as an application of our proof framework.

