Ncipher Corporation Limited

Ian Nigel Harvey

Michael Lee Gregory

Jason Edward Pintok

Adrian Peck

Utility meter dual transceiver boards

A secure time stamping device uses multiple virtual clocks, each of which may be individually accessed and calibrated. A digital key is associated with each of the clocks. All of the virtual clocks use a common timer (), with the actual clock output being generated by applying calibration information () for that clock to the timer () output. A user wishing to have a message time stamped presents that message along with information as to which virtual clock to be used at a device input (). The appropriate calibration information () is then selected and the timer () output is compensated accordingly. The incoming message plus the resultant time are concatenated and automatically signed using the key () applicable to that particular virtual clock.

Time stamping system

A method for the secure transmission of data from a distributor to a client over a computer network. The method includes encrypting the data using an encryption confidentiality key known to the client, but not the distributor. The method also includes storing the encrypted data at the distributor and generating a message by further encrypting the encrypted data using an encryption transmission key. The corresponding transmission decryption key is also known by the client. Also, the method includes transmitting the generated message to the client.

Secure transmission of data within a distributed computer system

The invention relates to a method of storing items of data in a memory device. The memory device has an array of a storage locations, each identified by an address corresponding to a unique multi-bit index value. The data items consist of a multi-bit identifier value and an information value. The method includes generating a first index value corresponding to the address of a fist storage location as a first function of the identifier value of an item of data and a first number from a predetermined sequence of numbers. If the first storage location is unoccupied, the item of data is stored therein. Alternatively, if the first storage location is already occupied, a second index value corresponding to the address of a further storage location is generated as a function of the identifier value and a second number from the predetermined sequence of numbers. If the further storage location is unoccupied, the item of data is stored therein. The invention also relates to a memory device for storing items of data.

Data storage and retrieval

A method is described of managing memory in a microprocessor system comprising two or more processors (40, 42). Each processor (40, 42) has a cache memory (44, 46) and the system has a system memory (48) divided into pages subdivided into blocks. The method is concerned with managing the system memory (48) identifying areas thereof as being 'cacheable', 'non-cacheable' or 'free'. Safeguards are provided to ensure that blocks of system memory (48) cannot be cached by two different processors (40, 42) simultaneously.

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Fen Ditton, United Kingdom

Ian Nigel Harvey