Eisuke Koizumi

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We propose a password-protected secret sharing scheme which is provably secure without the random oracles. Three tools enable us to achieve this property: the IND-CCA secure threshold encryption scheme of Libert and Yung, the linear encryption scheme and the technique for constructing a simulation-sound non-interactive zero knowledge proof for any language(More)
For the identity-based aggregate signatures, Hohenberger, Sahai and Waters proposed the first scheme that admits unrestricted aggregation, using multilinear maps. On the other hand, for the attribute based-signatures, which is an extended notion of the identity-based signatures, the ones with aggregation are not known to exist so far. This paper studies the(More)
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