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Impossibility of finding any third family of server protocols integrating Byzantine quorum systems with threshold signature schemes

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  • A preliminary version of this paper appeared under the title “Impossibility of finding any third family of server protocols integrating Byzantine quorum systems with threshold signature schemes,” in Proc. of the Sixth International ICST Conference on Security and Privacy in Communication Networks (SecureComm 2010), Singapore, September 2010 [49].

Correspondence: Jingqiang Lin, State Key Laboratory of Information Security, Institute of Information Engineering, Chinese Academy of Sciences, Minzhuang Road 89A, Beijing 100195, China.

E-mail: linjq@lois.cn

ABSTRACT

To tolerate servers' Byzantine failures, a distributed storage service of self-verifying data needs to make three security properties be Byzantine fault tolerant (BFT): data consistency, data availability, and confidentiality of the signing service's private key. Building such systems demands the integration of Byzantine quorum systems (BQSs), which only make data consistency and availability be BFT, and threshold signature schemes (TSSs), which only make confidentiality of the private key be BFT. Two families of valid TSS-BQS systems (of which the server protocols carry all the design options) have been proposed in the literature. Motivated by the failures in finding a third family of valid server protocols, we study the reverse problem and formally prove that it is impossible to find any third family of valid TSS-BQS systems. To obtain this proof, we develop a validity theory on server protocols of TSS-BQS systems. It is shown that the only two families of valid server protocols, “predicted” (or deduced) by the validity theory, precisely match the existing protocols. Copyright © 2012 John Wiley & Sons, Ltd.

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