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A nonrepudiable threshold proxy signcryption scheme with known proxy agent. (English) Zbl 1107.68323

Summary: M. Mambo, K. Usuda and E. Okamoto [“Proxy signatures: Delegation of the power to sign message”, IEICE Trans. Fundamentals of Electronics, Communications and Computer Sciences E79-A (9), 1338–1353 (1996)] introduced the concept of proxy signature. However, a proxy signature only provides the delegated authenticity and does not provide the confidentiality. Chan and Wei proposed a threshold proxy signcryption scheme (denoted as Chan-Wei scheme), which extended the concept of proxy signature. In this paper, the authors demonstrate that the Chan Wei scheme does not satisfy strong unforgeability, strong nonrepudiation and strong identifiability. Based on the Chan-Wei scheme, a nonrepudiable threshold proxy signcryption scheme with known proxy agents is proposed. The proposed scheme overcomes the weaknesses of Chan-Wei scheme. Completeness proof and security analysis of the proposed scheme are presented. In addition, compared with Chan-Wei scheme, the proposed scheme exactly finds out which proxy agents present bogus secret shadow or tamper secret shadow.

MSC:

68M10 Network design and communication in computer systems
68P25 Data encryption (aspects in computer science)

Keywords:

Chan-Wei scheme
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