RETRIEVABLE CRYPTOGRAPHIC SYSTEM, RETRIEVABLE CRYPTOGRAPHIC METHOD, STORAGE DEVICE, RETRIEVAL DEVICE AND REGISTRANT DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a system which can cancel a retrieval right of a registered user empowered to retrieve a database including a cryptogram of a keyword.

SOLUTION: An encrypted database including tag information is stored in a storage device. The tag information includes a cryptogram corresponding to a vector which corresponds to a property of a registered user and a keyword, and a first value which is an image of a searcher's key of the registered user. This cryptogram is a cryptogram of an encrypted second value which is an image of a set of the first value and an interpolation key of the registered user. A retrieval device generates a retrieval query which is a decryption key corresponding to a vector which corresponds to the property of the registered user and a retrieval keyword. A retrieval proxy device stores the interpolation key of the registered user and verifies if a decrypted value which is gained by decrypting the cryptogram included in the tag information of the encrypted database using the retrieval query as a decryption key corresponds to a set of the first value included in the tag information and the interpolation key stored in an interpolation key storage part.

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