Abstract: Various examples described herein are directed to systems and methods for generating data values using a NAND flash array. A memory controller may read a number of memory cells at the NAND flash array using an initial read level to generate a first raw string. The memory controller may determine that a difference between a number of bits from the first raw string having a value of logical zero and a number of bits from the first raw string having a value of logical one is greater than a threshold value and read the number of memory cells using a second read level to generate a second raw string. The memory controller may determine that a difference between a number of bits from the second raw string having a value of logical zero and a number of bits from the second raw string having a value of logical one is not greater than a threshold value and applying a cryptographic function using the second raw string to generate a first PUF value.