A system which identifies a memory device using a physical unclonable function. The system performs raw read operations on every page of a block; sorts the pages into low and high groups using an average number of ones based on the raw read operations; generates unordered page pairs by sequentially selecting a first page from the low group and a second page from the high group; generates ordered page pairs by selectively converting an order of pages in each pair of the unordered page pairs; and generates a sequence for identifying the selected block based on comparing the average number of ones for pages in each ordered page pair.