Xinhui Lai

Xinhui Lai, Maksim Jenihhin, Georgios Selimis et al.

Physical Unclonable Functions (PUFs) are gaining attention in the cryptography community because of the ability to efficiently harness the intrinsic variability in the manufacturing process. However, this means that they are noisy devices and require error correction mechanisms, e.g., by employing Fuzzy Extractors (FEs). Recent works demonstrated that applying FEs for error correction may enable new opportunities to break the PUFs if no countermeasures are taken. In this paper, we address an attack model on FEs hardware implementations and provide a solution for early identification of the timing Side-Channel Attack (SCA) vulnerabilities which can be exploited by physical fault injection. The significance of this work stems from the fact that FEs are an essential building block in the implementations of PUF-enabled devices. The information leaked through the timing side-channel during the error correction process can reveal the FE input data and thereby can endanger revealing secrets. Therefore, it is very important to identify the potential leakages early in the process during RTL design. Experimental results based on RTL analysis of several Bose-Chaudhuri-Hocquenghem (BCH) and Reed-Solomon decoders for PUF-enabled devices with FEs demonstrate the feasibility of the proposed methodology.

Xinhui Lai, Maksim Jenihhin, Jaan Raik et al.

A large number of crypto accelerators are being deployed with the widespread adoption of IoT. It is vitally important that these accelerators and other security hardware IPs are provably secure. Security is an extra functional requirement and hence many security verification tools are not mature. We propose an approach/flow-PASCAL-that works on RTL designs and discovers potential Timing Side-Channel Attack(SCA) vulnerabilities in them. Based on information flow analysis, this is able to identify Timing Disparate Security Paths that could lead to information leakage. This flow also (automatically) eliminates the information leakage caused by the timing channel. The insertion of a lightweight Compensator Block as balancing or compliance FSM removes the timing channel with minimum modifications to the design with no impact on the clock cycle time or combinational delay of the critical path in the circuit.