摘要 |
A core for a register-based programmable logic device includes a register configured to provide a hidden identifier in response to a secret unlock operation. The identifier is inaccessible during normal operation of the core implementation. The unlock operation is selected to be an action or set of actions that would typically not be performed during normal use of the core implementation. The logic associated with providing the hidden identifier in response to the unlock operation is configured to not interfere with normal operation of the core implementation. Therefore, the presence of this source identification capability is transparent to regular users (and unauthorized copyists) of the core implementation. The availability of the secondary identifier can be limited in duration to minimize the chances of accidental, or even intentional, discovery.
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