Paper 2020/892

Pushing the Limits of Fault Template Attacks: The Role of Side-Channels

Sayandeep Saha and Arnab Bag and and Debdeep Mukhopadhyay

Abstract

Fault Template Attack (FTA) is a recently proposed class of fault attacks, which exploits the fact that activation and propagation of a fault through combinational logic is data-dependent. Even at the presence of masking and state-of-the-art fault countermeasures, FTA can perform key recovery even at the middle rounds of block ciphers without any access to the ciphertexts. The templates can combine information from different fault locations and cipher executions. This capability of templates is quite powerful and may lead to stronger attacks. In this paper, we enhance the FTA attacks by considering side-channel in- formation during fault injection. Some of the recently proposed combined countermeasures against Statistical Ineffective Fault Analysis (SIFA) and Side-Channel Attack (SCA) fall prey against FTA after this enhance- ment. The success of the proposed attacks stem from some non-trivial fault propagation properties of S-Boxes, which remained unexplored in the original FTA proposal. We also relax the fault model to some extent from that of the original FTA. The proposed attacks are validated on the hardware implementation of a masked χ 3 S-Box through gate-level power trace simulation, establishing its practicality and efficacy.