A Tightly-Secure Multisignature Scheme with Improved Verification

Jong Hwan PARK  Young-Ho PARK  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E99-A   No.2   pp.579-589
Publication Date: 2016/02/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E99.A.579
Type of Manuscript: PAPER
Category: Cryptography and Information Security
multisignature,  proof-of-possession,  bilinear maps,  coCDH problem,  tight reduction,  POP-sKR model,  

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A multisignature (MS) scheme enables a group of signers to produce a compact signature on a common message. In analyzing security of MS schemes, a key registration protocol with proof-of-possession (POP) is considered to prevent rogue key attacks. In this paper, we refine the POP-based security model by formalizing a new strengthened POP model and showing relations between the previous POP models and the new one. We next suggest a MS scheme that achieves: (1) non-interactive signing process, (2) O(1) pairing computations in verification, (3) tight security reduction under the co-CDH assumption, and (4) security under the new strengthened POP model. Compared to the tightly-secure BNN-MS scheme, the verification in ours can be at least 7 times faster at the 80-bit security level and 10 times faster at the 128-bit security level. To achieve our goal, we introduce a novel and simple POP generation method that can be viewed as a one-time signature without random oracles. Our POP technique can also be applied to the LOSSW-MS scheme (without random oracles), giving the security in the strengthened POP model.