Fault intensity map analysis with neural network key distinguisher

Physical cryptographic implementations are vulnerable to side-channel attacks, including fault attacks, which can be used to recover a secret key. Using a deep neural network (NN) with fault intensity map analysis (FIMA), we present a new highly efficient statistical fault injection analysis (FIA) technique called FIMA-NN. This technique employs a convolutional neural network to rank the key candidates based on multiple features in data distribution under fault with varying intensities and generalizes most existing statistical techniques including fault sensitivity analysis, differential fault intensity analysis, statistical ineffective fault analysis, and FIMA. As FIMA-NN does not rely on a single feature of data distribution, it is successful even in the presence of a wide variety of countermeasures against FIA. We introduce a generic statistical model for timing failure attacks using dynamic timing analysis of an AES S-box implemented in TSMC 65 nm technology with standard ASIC design flow. Using the simulated fault mechanism, we demonstrate that, in terms of required amount of collected ciphertexts, FIMA-NN is 12.6 times more efficient than statistical techniques using bias alone, when faulty and fault-free values are not filtered. Further, in the presence of error detection and infective countermeasures, FIMA-NN is 4.8 and 5 times more efficient than bias-alone techniques, respectively.