An array of bit cells is programmed with user data, each row including a corresponding word line and each column including a corresponding column line. The array includes a plurality of differential PUF bits, each having a first and second bit cell programmed with user data. A first set of sense-amplifiers outputs a set of data bits of the user data, and a second set of sense-amplifiers outputs a set of differential bits, each differential bit based on a differential current between two columns lines of the selected column lines corresponding to the first and second bit cells of a corresponding differential PUF bit along the selected word line. A potential PUF bit generator outputs a set of potential PUF bits based on the set of data bits of the user data from the first set of sense-amplifiers and the set of differential bits from the second set of sense-amplifiers.