Cryptography – Particular algorithmic function encoding – Nbs/des algorithm
Patent
1996-04-30
1998-01-13
Cain, David C.
Cryptography
Particular algorithmic function encoding
Nbs/des algorithm
380 4, H04K 100
Patent
active
057087156
ABSTRACT:
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.
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Cain David C.
Hewlett--Packard Company
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