Wave Systems, Inc.

Wave System Corp.

John R Michener

Gregory J Kazmierczak

Kathryn M Smith

Benjamin Samit

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.

Encrypted data package record for use in remote transaction metered data

A cryptographic communications system includes a method and apparatus for sending and receiving a plurality of encrypted signal packets in a system for metering the use of encrypted information. Plural packet communication between a user terminal containing a remote cryptographic control unit and a cryptographic operations center typically includes uploading usage records and downloading credit. Plural packet messages are protected to detect alterations in the form of packet reordering by cross linking data cryptographic codes and message authentication codes (MAC). In particular, a first cryptographic code key is used to encrypt a first plurality of signal packets. A second cryptographic code key is used to encrypt the encrypted first plurality of signal packets to form an appended MAC. The initial vector for computing the MAC for a given packet is the last encrypted data block of the previous packet encrypted with the first cryptographic code key. In such manner, each MAC is a function of the present packet and all previous packets, thereby providing an increased level of security against signal tampering by reordering of packets.

Secure communication system with cross linked cryptographic codes

A cryptographic communications system includes a method and apparatus for exchanging messages between a user terminal, containing a secret key, and an operations center wherein each party authenticates signals received from the other party before any other information is exchanged. An initial identification message from the user terminal to the operations center contains an encrypted value of current time. The operations center checks the received message against local time to verify real time concurrent operation of the user terminal. Subsequently, the operations center and the user terminal mutually exchange encrypted challenge blocks, and each provide respective encrypted responses to the encrypted challenge blocks. The challenge and response exchanges demonstrate that each knows the secret key stored in the user terminal before other information, such as downloaded credit or uploaded data usage, is exchanged. In particular, the challenge and response messages exchange a first random number generated in the user terminal and a second random number generated in the operations center, which are variables used in conjunction with the user secret key to generate a new session key for encrypting the remainder of the messages exchanging data in the communication session.

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Neshanic Station, NJ, United States of America

John R Michener