Statistical tests to determine spatial correlations in the response behavior of PUF

The level of security provided by physically unclonable functions (PUFs) strongly depends on the unpredictability of its challenge-response behavior. Systematic variation in the properties of a PUF might introduce correlations in the output bits. The mutual dependence of response bits is typically not detected by conventional methods, thus leaving the PUF vulnerable to prediction attacks. New methods accounting for the spatial distribution of response bits are presented, allowing to detect security leaks due to correlation effects at device level. The presented methods are easily applicable to a wide-range of array-based PUFs.