Paper 2021/1132

Safe-Error Attacks on SIKE and CSIDH

Fabio Campos and Juliane Krämer and Marcel Müller

Abstract

The isogeny-based post-quantum schemes SIKE (NIST PQC round 3 alternate candidate) and CSIDH (Asiacrypt 2018) have received only little attention with respect to their fault attack resilience so far. We aim to fill this gap and provide a better understanding of their vulnerability by analyzing their resistance towards safe-error attacks. We present four safe-error attacks, two against SIKE and two against a constant-time implementation of CSIDH that uses dummy isogenies. The attacks use targeted bitflips during the respective isogeny-graph traversals. All four attacks lead to full key recovery. By using voltage and clock glitching, we physically carried out two of the attacks - one against each scheme -, thus demonstrate that full key recovery is also possible in practice.