| 摘要 |
<p>An integrated circuit device (chip) 10 has lock circuitry (11) that controls operational enablement of a functional block (12) 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 20 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 (11) is subjected to the same one-way function in block (26) before being compared with the stored chip-key in comparator (27); if a match is found, a gating circuit (18) is enabled to pass a necessary signal (such as a clock signal) to the functional block (12). By way of example, the secure communication block (20) may implement the Diffie-Hellman Key Exchange algorithm whilst the one-way function block (26) may implement a one-way hash function such as effected by the Secure Hash Algorithm. <IMAGE></p> |
