Controller Datapath Aware Verification of Masked Hardware Generated via High Level Synthesis
This work addresses a critical verification challenge for hardware designers using HLS to generate secure masked implementations, preventing false positives that could undermine security assessments.
The paper tackles the problem of verifying Power Side Channel Attack (PSCA) security in masked hardware generated via High Level Synthesis (HLS), which can produce false positives with existing tools due to resource-shared datapaths. It proposes MaskedHLSVerif, a toolflow that performs state-wise formal verification to avoid these false positives and correctly verifies standard cryptographic benchmarks, including cascaded masked gadgets and the PRESENT S-box, where existing tools like REBECCA fail.
Masking is a countermeasure against Power Side Channel Attacks (PSCAs) in both software and hardware implementations of cryptographic algorithms. Compared to software masking, implementing masked hardware is time consuming and error prone. Recent approaches, therefore, rely on High Level Synthesis (HLS) tools to automatically generate masked Register Transfer Level (RTL) hardware from verified masked software, significantly reducing design effort. Since HLS was never developed for security, HLS optimizations may impact PSCA security of the generated RTL. As a result, verifying the PSCA security of HLS generated masked RTL is crucial. Existing hardware masking verification tools can verify masked hardware, but may produce false positives when applied to HLS generated designs with controller datapath architectures obtained due to resource-shared datapath obtained via HLS. This work proposes a hardware masking verification strategy for HLS generated masked hardware. Our toolflow MaskedHLSVerif, performs state-wise formal verification of controller datapath RTL obtained via HLS, thereby avoiding false positives caused by resource-shared datapaths. Our tool flow correctly verifies standard cryptographic benchmarks, consisting of cascaded masked gadgets and the PRESENT S-box masked with gadgets, where existing tools like REBECCA reports false positives. The proposed tool-flow is able to detect masking flaws induced by HLS-optimizations as well.