An Evaluation of LM35 Temperature Sensors as Physical Unclonable Functions

This paper explores the feasibility of employing LM35 temperature sensors as Physical Unclonable Functions (PUFs) for secure identification and cryptographic applications. PUFs exploit inherent hardware variations to generate unique and non-replicable identifiers, offering a novel alternative to traditional cryptographic keys. Five LM35 sensors were tested in controlled indoor and dynamic outdoor environments to assess their uniqueness, robustness, and stability. The sensors' voltage outputs, influenced by manufacturing tolerances and intrinsic variations, were analyzed for potential use as cryptographic tokens. The results demonstrated that while the different sensors exhibited some response variation, their outputs lacked the consistency and distinctiveness required for robust PUF applications. Controlled conditions yielded more stable responses, whereas outdoor environments introduced variability that compromised reliability. These findings underscore the limitations of LM35 sensors as PUFs, suggesting the need for dedicated security modules or hybrid approaches to achieve practical security solutions. Our study highlights challenges in sensor-based PUFs and offers insights for future research.