Identity-Based Key-Insulated Aggregate Signatures, Revisited
Identity-based key-insulated cryptography is a cryptography which allows a user to update an exposed secret key by generating a temporal secret key as long as the user can keep any string as its own public key. In this work, we consider the following question; namely, can we construct aggregate signatures whereby individual signatures can be aggregated into a single signature in an identity-based key-insulated setting? We call such a scheme identity-based key-insulated aggregate signatures (IBKIAS), and note that constructing an IBKIAS scheme is non-trivial since one can aggregate neither each signer’s randomness nor components depending on the temporal secret keys. To overcome this problem, we utilize the synchronized technique proposed by Gentry and Ramzan (PKC’06) for both aas state information and a partial secret key generated by a secure device. We then show that the proposed scheme is still provably secure under an adaptive security model of identity-based aggregate signatures.
KeywordsKey-insulated signatures Identity-based signatures Aggregate signatures
We would like to thank the anonymous reviewers for their helpful comments. This work was supported in part by JSPS KAKENHI Grant Numbers 16K16065 and 17K00178, and Secom Science and Technology Foundation.
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