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摘要

PROBLEM TO BE SOLVED: To provide a signature method to confirm that the number of participant devices which signs on is not less than t (a set T) and is not more than t' (a set T') when s units of the participant device (a set S) included in n units of the participant device (an aggregate N) sign on.;SOLUTION: A one-time public key and a public key are associated with each other by equalizing discrete logarithms of the one-time public key and public key of a signatory based on an origin whose discrete logarithm problem is unclear. In each of participant devices that signs on and are included in the set S, a one-time public key _i (iS) {note: "" denotes that i is an element of the set S and hereinafter the same} is produced so as to equalize the discrete logarithms between public key y_i and the one-time public key _i. Besides, in collaboration of participant devices included in the set S, the one-time public key _i (iT'-S) included in a set (T'-S) is produced. A one-time public key _i (iN-T') included in a set (N-T') is determined by calculation using a polynomial expression of t'-th order determined from _i (iT'). After producing the one-time public key, the signature is made.;COPYRIGHT: (C)2007,JPO&INPIT