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US 7,549,059 B2Granted
Transferring data values via a data bus or storing data values using a selectable representation
AssigneeArm Limited
InventorSimon Charles Watt
Life of this patent
Estimating the term…
Abstract
Data values being stored and transferred within a data processing system 8 have a selectable representation, such as true and complement, as indicated by an accompanying representation specifying bit. This assists in obscuring the operation and the power signature of the device in a manner that improves security.
Claims40
Apparatus for processing data, said apparatus comprising:
- a data source operable to supply a data value to be processed;
- a destination operable to receive said data value;
- and
- a data bus operable to transfer a representation of said data value between said data source and said destination;
- wherein one or more representation specifying bits are associated with said data value transferred on said data bus, said one or more representation specifying bits specifying which of a plurality of different representations of said data value is used to transfer said data value via said data bus between said data source and said destination, and
- wherein said one or more representation specifying bits accompany said data value transferred on said data bus and said one or more representation specifying bits are a complement bit specifying whether said data value is represented in a true form or a complement form, and
- wherein said apparatus is one of:
- a smart card;
- a cryptographic device;
- and
- a secure device.
8 more elements
A method of processing data in a data processing apparatus, said method comprising the steps of:
- supplying from a data source a data value to be processed;
- and
- transferring a representation of said data value between said data source and a destination via a data bus;
- wherein
- one or more representation specifying bits are associated with said data value supplied by said data source, said one or more representation specifying bits specifying which of a plurality of different representations of said data value is used to transfer said data value via said data bus between said data source and said destination,
- wherein said one or more representation specifying bits accompany said data value transferred on said data bus and said one or more representation specifying bits are a complement bit specifying whether said data value is represented in a true form or a complement form, and
- wherein said apparatus is one of:
- a smart card;
- a crypotographic device;
- and
- a secure device.
8 more elements
Apparatus for processing data said apparatus comprising:
- a store operable to store a data value and one or more representation specifying bits associated with said data value, said one or more representation specifying bits specifying which of a plurality of different representations of said data value is used to store said data value within said store,
- wherein said one or more representation specifying bits accompany said data value transferred on said data bus and said one or more representation specifying bits are a complement bit specifying whether said data value is represented in a true form or a complement form, and
- wherein said apparatus is one of:
- a smart card;
- a cryptographic device;
- and
- a secure device.
4 more elements
A method of processing data, said method comprising:
- storing a data value and one or more representation specifying bits associated with said data value, said one or more representation specifying bits specifying which of a plurality of different representations of said data value is used to store said data value within a store,
- wherein said one or more representation specifying bits accompany said data value transferred on said data bus and said one or more representation specifying bits are a complement bit specifying whether said data value is represented in a true form or a complement form, and
- wherein said apparatus is one of:
- a smart card;
- a cryptographic device;
- and
- a secure device.
4 more elements
Dependencies are inferred from the claim text.