Evaluation of a median threshold based EEPROM-PUF concept implemented in a high temperature SOI CMOS technology

Physically Unclonable Functions (PUFs) are a new type of hardware-bounded cryptographic primitives. PUFs leverage random process variations to generate unique keys suitable for the use in low-cost device identification and authentication applications. Since the keys are typically derived from a large number of semiconductor devices, a space- and power-saving implementation of PUFs in non-volatile memory is appealing. In this paper, a median threshold based PUF concept was experimentally evaluated for 68 EEPROM arrays fabricated in a high temperature 1 ßm SOI CMOS technology. As-is realization of the concept yielded poor results regarding the randomness and uniqueness of the generated keys featuring an average inter-Hamming distance of only 30.24% (ideal value: 50%). The observed bias could be attributed to the presence of systematic trends induced by an asymmetric cell layout of the EEPROM arrays. To mitigate the effect of systematic process variations, a simple optimization procedure is proposed that has significantly increased the average inter-Hamming distance by more than 18 percentage points.