| 摘要 |
A group signature system according to one embodiment of the present invention comprises a group administrator apparatus, signer apparatuses and a verifier apparatus which can communicate with one another. Here, in a group signature method used by the apparatuses, a multiplication cyclic group or a bilinear group in which an order is unknown as in RSA is not used at all, but a multiplication cyclic group gG of a prime order q is only used, and representation parts ki1 and ki2 are used as a member private key. Moreover, as information for tracing a signer, Ti=G1̂{ki1} is utilized, and ki1 is utilized for verifying revocation. In consequence, a calculation amount can be decreased to increase a calculation speed as compared with conventional [CG04], [FI05] and [DP06] systems.
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