Behavioral and Physical Unclonable Functions (BPUFs): SRAM Example

Physical Unclonable Functions (PUFs) have gained a great interest for their capability to identify devices uniquely and be lightweight primitive in cryptographic protocols. However, several reported attacks shown that virtual copies (mathematical clones) as well physical clones of PUFs are possible, so they cannot considered tamper-resistant or tamper-evident, claimed. The solution presented this article is extend the until now, which only physical, make them Behavioral (BPUFs). Given challenge, BPUFs provide not but also behavioral distinctive response caused by manufacturing process variations. Hence, more difficult attack than since responses associated challenges predicted cloned. obtained from measurements taken at sample times proposed. In way, can detect if manipulated. analysis done current extended allow versatility BPUFs. Particularly, Jaccard instead Hamming distances proposed evaluate similarity responses. As example validate solution, based on Static Random-Access Memories (SRAM BPUFs), with one given challenges, were analyzed experimentally using integrated circuits fabricated 90-nm CMOS technology. If an attacker succeeds cloning reported, does way obtain responses, fails SRAM highest probability succeed brute-force was estimated experimental results $1.5 \cdot 10^{-34}$ , considering influence changes operating conditions (power supply voltage, temperature, aging).