A physically unclonable function (PUF) system is provided. The PUF system includes an entropy source, a plurality of selectable paths, a random selection block, and error correction logic. The plurality of selectable paths are formed between the entropy source and an output for providing a PUF response. The random selection block is for randomly selecting one of the plurality of selectable paths in response to receiving a challenge. The error correction logic is coupled to the output for receiving the PUF response and for correcting any errors in the PUF response for the plurality of selectable paths. By using a different path through the entropy source each time a challenge is received, protection is provided against side-channel attacks.