| 摘要 |
PROBLEM TO BE SOLVED: To verify repetitive signs, etc., given to signed documents together by allowing each signer to generate two pieces of information by using two unidirectional functions and generating a sign including those components. SOLUTION: A checker finds information Ii corresponding to identification information IDi included in the ID'i in received information (ID'i, X'i, m'i, yi) and two unidirectional functions fi and hi from open information (IDi, Ii, fi, hi) and fine ei and di by using unidirectional functions fi and hi of equation I of ei=fi(X'i, m'i) and equation II of di=hi(X'i, m'i) and received X'i and m'i. Further, Xi included in received X'i is extracted to perform operation di*Xi between di and Xi and operation ei*Ii between ei and Ii and as to the operation results, equation III of Z'=V((Xi*di), (Ii*ei)|i=1,..., L) is found from a function V. Further, the operation result yi*βbetween yi andβis set in a functionΓto find W=Γ(yi*β) and W=Z' is compared; when the equal sign is satisfied, it is decided that all signs are not illegal.
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