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US 5,708,715 AGranted
Integrated circuit device with function usage control
AssigneeHewlett-Packard Company
InventorDominique Vicard
Life of this patent
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AssigneeHewlett-Packard Company
InventorDominique Vicard
Estimating the term…
An integrated circuit device (chip) has lock circuitry that controls operational enablement of a functional block of the chip. To unlock the lock circuitry, a "chip-key" must be supplied to the chip over a secure communications link, the chip-key being communicated in encrypted form and then decrypted in a secure communication block of the chip. To prevent internal examination of the chip revealing the chip key, the latter is not stored as such in the chip. Instead, only a signature of the chip-key is stored, the latter being formed from the chip-key by subjecting the latter to a one-way function. The chip-key input to the lock circuitry is subjected to the same one-way function in block before being compared with the stored chip-key in comparator; if a match is found, a gating circuit is enabled to pass a necessary signal (such as a clock signal) to the functional block. By way of example, the secure communication block may implement the Diffie-Hellman Key Exchange algorithm whilst the one-way function block may implement a one-way hash function such as effected by the Secure Hash Algorithm.
An integrated circuit device comprising a functional block for providing the device with a required functionality, and lock circuitry for inhibiting operation of said functional block until the provision to the lock circuitry, from externally of the device, of at least one predetermined chip key in encrypted form;
A standard cell for incorporation into an integrated circuit device to control operational enablement of a functional block of the device, the standard cell comprising:
Dependencies are inferred from the claim text.