Content data management system and method

Embodiments of the present invention provide a simplified authentication transaction for reconnecting a storage device to a host apparatus that has completed authentication in the past. According to one embodiment, an authentication log is recorded in the host. Plural units of this log information are recorded in the storage device. At the time of transferring a content decryption key and usage rules between the host and the storage device, the decryption key and usage rules are recorded into the host as a log for the transfer. The used authentication log is recorded into the storage device as RAPDI. If RAPDI indicates the authentication log in the simplified authentication transaction, recovery transaction is permitted. The host device deletes/invalidates or holds the log for the transfer in accordance with non-permission/permission. In the case of permission, the key and usage rules are recovered by using a log for the transfer prior to the simplified authentication transaction.