Importance

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Abstract

The disclosed system relates to metered use cryptographic systems, and particularly to a data package and system operation for effecting metered purchases of encrypted data from a local encrypted database. A local CD ROM encrypted database includes one or more data package records containing one or more message keys encrypted under a database key, and one or more data packages encrypted under said message keys. The user decrypts portions of the database, and the data used is metered locally and recorded as a stored data usage record. The local stored data usage record is reported by telephone modem or other telecommunications link from a remote user terminal, such as a host personal computer containing a remote cryptographic control unit, to a cryptographic operations center. A second embodiment of an encrypted database for use in accordance with the present invention includes a header containing a message key encrypted under said database key, one or more subunit message keys encrypted under said message key, and a subunit data package encrypted under each said subunit message key. The subunit message key is selected to save storage space. The present system further permits a remote transaction mode in which an on line purchase of data from the encrypted database is affected in real time. Flexible system mechanisms include controls over purchase price, start times and expiration times, permission to purchase data on line and off line, and a time window within which purchased data may be decrypted.

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First Claim