Integrated Circuit PUF Key Generation with Fuse Control

The patent extracts the secret key from non-volatile memory and instead generates it dynamically using a Physical Uncloneable Function (PUF). The PUF generates the key based on physical characteristics of the hardware itself, eliminating the need to store the key in memory. This resolves the contradiction by providing key accessibility when needed while preventing unauthorized access, as the key cannot be extracted or stolen from memory.

The patent introduces a fuse mechanism as an intermediary between the PUF key generator and the authentication system. The fuse acts as a one-time switch that, once broken, permanently enables or disables key access. This intermediary layer adds a security checkpoint that prevents unauthorized key retrieval while maintaining legitimate access during the authorization window, thus resolving the accessibility versus security contradiction.

The patent applies preliminary action by establishing an authorization mechanism before the key becomes permanently inaccessible. A fuse is configured to break after a predetermined number of readout attempts or after a specific time period, creating a limited window of opportunity for legitimate key access. This preliminary setup ensures that security against cloning is maintained while providing controlled key readout capability during the authorization period.

The patent changes the parameter of key accessibility from permanent to temporary by using the fuse mechanism. The fuse remains intact during the authorization period, allowing key readout, but breaks after the predetermined conditions are met, permanently disabling further access. This parameter change resolves the contradiction by providing temporary readout capability while maintaining long-term security against cloning.