System to generate a signature key and method of operating the same

A method for utilizing a plurality of physical unclonable function (PUF) cells to generate a signature key with a desired bit length, the method comprising:

• setting a state of each of the plurality of PUF cells to a uniform level;
• sampling the state of a portion of the plurality of PUF cells to obtain a plurality of state changing information, the plurality of state changing information corresponding to the portion of the plurality of PUF cells, wherein the number of the plurality of state changing information is less than the number of the plurality of PUF cells;
• and
• generating the signature key based on the plurality of state changing information, wherein the desired bit length of the signature key is greater than the number of the plurality of state changing information.

A system to generate a signature key, comprising:

• a plurality of physical unclonable function (PUF) cells;
• a controller, arranged for setting a state of each of the plurality of PUF cells to a uniform level;
• a state determination device, arranged for obtaining an order of change in the state of at least a portion of the plurality of PUF cells;
• and
• an encoder arranged for generating a signature key at least based on the order.