Sram based physically unclonable function and method for generating a puf response

Abstract

A physically unclonable function (PUF) is implemented in a plurality of SRAM cells. In a method for generating a PUF response, a logic zero is first written to all the SRAM cells of the PUF. A bit line coupled to the storage node that stores the logic zero of each SRAM cell is biased to a predetermined voltage. The bit lines are then selected for an evaluation read operation. During the evaluation read, a read current of one of the bit lines from one column is converted to a first voltage and a read current of another bit line of another column is converted to a second voltage. The first voltage is then compared to the second voltage. A logic state of a bit of the PUF response is determined as a result of the comparison. The logic bit may be provided to the input of a parallel-in serial-out shift register. There may be a comparator for each logic bit, or a few comparators may be shared between the logic bits. The PUF response may be used to provide a signature for the data processing system. The back-bias of each cell may be selectively adjusted.