Paper 2023/1559

AprèsSQI: Extra Fast Verification for SQIsign Using Extension-Field Signing

Maria Corte-Real Santos, University College London
Jonathan Komada Eriksen, Norwegian University of Science and Technology
Michael Meyer, University of Regensburg
Krijn Reijnders, Radboud University Nijmegen

We optimise the verification of the SQIsign signature scheme. By using field extensions in the signing procedure, we are able to significantly increase the amount of available rational $2$-power torsion in verification, which achieves a significant speed-up. This, moreover, allows several other speed-ups on the level of curve arithmetic. We show that the synergy between these high-level and low-level improvements gives significant improvements, making verification $2.07$ times faster, or up to $3.41$ times when using size-speed trade-offs, compared to the state of the art, without majorly degrading the performance of signing.

Available format(s)
Public-key cryptography
Publication info
A minor revision of an IACR publication in EUROCRYPT 2024
post-quantum cryptographyisogeniesSQIsignverification
Contact author(s)
maria santos 20 @ ucl ac uk
jonathan k eriksen @ ntnu no
michael @ random-oracles org
krijn @ cs ru nl
2024-03-05: revised
2023-10-10: received
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Creative Commons Attribution


      author = {Maria Corte-Real Santos and Jonathan Komada Eriksen and Michael Meyer and Krijn Reijnders},
      title = {{AprèsSQI}: Extra Fast Verification for {SQIsign} Using Extension-Field Signing},
      howpublished = {Cryptology ePrint Archive, Paper 2023/1559},
      year = {2023},
      note = {\url{}},
      url = {}
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