eprint.iacr.orgpaper

Power Analysis on SQIsign via Ideal Reconstruction from Quaternion Leakages

ePrint paper identifying five side-channel vulnerabilities in the signing procedure of Round-3 SQIsign, the isogeny-based signature scheme in NIST's additional post-quantum signature process. It gives polynomial-time algebraic algorithms that recover the secret key from leaked quaternion/ideal intermediate values, including cases where only partial bits leak. It also demonstrates power analysis on the SQIsign source code to extract the needed leakage, which earlier work on Round-1 or toy parameters did not do.