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[Poster] SRAM-based Physically Unclonable Functions: The Impact of Environmental Conditions

Pascal Ahr; Marvin Reski; Zafira Irfana; Christoph Lipps; Hans Dieter Schotten
ACPI, 6/2023.


Static Random Access Memory (SRAM) is a volatile memoryinherently available in almost every computing unit. It consistsbasically of two cross coupled Complementary Metal-Oxide-Semiconductor (CMOS) inverters and two accesstransistors. This feedback structure causes abistable behavior during the start-up phase.Manufacturing deviations of the semiconductors lead tounique and characteristic cells with three different behaviorsduring the initial startup. Either it prefers to adopt logical statezero, logical state one, or there is no preferred adopted state.Those are so-called Startup-Values. A Physically Unclonable Function (PUF) generates a uniqueresponse (Startup-Value) out of a given challenge (Startup).PUFs are a sound security solution in the Industrial Internet of Things (IIoT), the Sixth-Generation (6G) Wireless Systems and the industrial Metaverse. Semiconductors like transistors and therefore the SRAM based PUF are influenced by environmental conditions. Two veryimportant aspects are supply voltage variation andtemperature.To evaluate the impact, two dedicated evaluation platformsfor both environmental conditions are designed andimplemented. The quality of a PUF is determined by threecommon metrics Uniqueness, Reliability and Uniformity. The results are shown exemplary for oneSRAM chip.