COCOALMA: A Versatile Masking Verifier

Masking techniques are an effective countermeasure against power side-channel attacks. Unfortunately, correctly masking a hardware circuit is difficult, and mistakes may lead to functionally correct circuits with insufficient protection. We present COCOALMA, a tool that formally verifies the side-channel resistance of stateful hardware circuits. Although COCOALMA was initially used to verify programs running on CPUs, we extended it to verify the security of several industrial masked hardware implementations. We give an overview of the tool’s structure, implementation details, optimizations that make it faster and more scalable than its predecessor REBECCA, and changes that enable verifying the probing security of any stateful hardware circuit. Finally, we evaluate COCOALMA with masked implementations of the PRINCE and AES ciphers.