KEY EXCHANGE DEVICE, KEY GENERATION DEVICE, KEY EXCHANGE SYSTEM, KEY EXCHANGE METHOD, AND PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide a key exchange system that can designate an access policy in exchanging a key and handle any attribute even after generating a master secret key and master public key.

SOLUTION: A key exchange system of the invention comprising at least a key exchange device α and key exchange device β exchanges a session key. When generating a long-term secret key by utilizing a linear secret distribution method in the key exchange system of the invention, a key generation device issues the long-term secret key S'A, äTA}, and äSA} as shared information of the linear secret distribution method based on an attribute set SAof the key exchange device α. The key exchange system designates an access policy of a partner in exchanging a key by allocating an access structure AAof linear secret distribution as the access policy in exchanging the key. A master secret key g^z and master public key (g, g^r, gT^z) which are independent of the attribute set are used in the invention.

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