Sina Schaeffler

PhD student in cryptography at ETH Zurich and IBM Research. Supervised by Luca De Feo and Kenneth Paterson.

Preprints

Qlapoty: Improved analysis and efficiency for quaternionic ideal to isogeny transformation
Max Duparc, Antonin Leroux and Sina Schaeffler. 2026.
eprint code
• Constant-time Quaternion Algorithms for SQIsign
  Andrea Basso, Chenfeng He, David Jacquemin, Fatna Kouider, Péter Kutas, Anisha Mukherjee, Sina Schaeffler and Sujoy Sinha Roy. 2025.
  eprint code

Research papers

• CORAL: Faster Group Action from Isogenies for Post-Quantum NIKE
  Andrea Basso, Giacomo Borin, Ryan Rueger and Sina Schaeffler. CRYPTO 2026. 2026.
  🏆 Best Paper Authored by Early Career Researchers.
  eprint code
• The SQInstructor: a guide to SQIsign and the Deuring Correspondence with level structures
  Giacomo Borin, Luca De Feo, Guido Maria Lido and Sina Schaeffler. CRYPTO 2026. 2026.
  eprint code
• Qlapoti: Simple and Efficient Translation of Quaternion Ideals to Isogenies
  Giacomo Borin, Maria Corte-Real Santos, Jonathan Komada Eriksen, Riccardo Invernizzi, Marzio Mula, Sina Schaeffler, and Frederik Vercauteren. ASIACRYPT 2025. 2025.
  eprint code
• Constant time lattice reduction in dimension 4 with application to SQIsign
  Otto Hanyecz, Alexander Karenin, Elena Kirshanova, Péter Kutas, and Sina Schaeffler. TCHES 2025. 2025.
  eprint code
• Towards Leakage-Resilient Ratcheted Key Exchange
  Daniel Collins, Simone Colombo, and Sina Schaeffler. PKC 2025. 2025.
  eprint

Technical documents

• SQIsign Algorithm specifications and supporting documentation Version 2.0
  Marius A. Aardal, Gora Adj, Diego F. Aranha, Andrea Basso, Isaac Andrés Canales Martínez, Jorge Chávez-Saab, Maria Corte-Real Santos, Pierrick Dartois, Luca De Feo, Max Duparc, Jonathan Komada Eriksen, Tako Boris Fouotsa, Décio Luiz Gazzoni Filho, Basil Hess, David Kohel, Antonin Leroux, Patrick Longa, Luciano Maino, Michael Meyer, Kohei Nakagawa, Hiroshi Onuki, Lorenz Panny, Sikhar Patranabis, Christophe Petit, Giacomo Pope, Krijn Reijnders, Damien Robert, Francisco Rodríguez Henríquez, Sina Schaeffler, and Benjamin Wesolowski. 2025.
  document website code
• SQIsign Algorithm specifications and supporting documentation Version 1.0
  Jorge Chavez-Saab, Maria Corte-Real Santos, Luca De Feo, Jonathan Komada Eriksen, Basil Hess, David Kohel, Antonin Leroux, Patrick Longa, Michael Meyer, Lorenz Panny, Sikhar Patranabis, Christophe Petit, Francisco Rodríguez Henríquez, Sina Schaeffler, and Benjamin Wesolowski. 2023.
  document website code

Master Thesis

• Algorithms for Quaternion Algebras in SQIsign
  Sina Schaeffler. Master Thesis at ETH Zurich, supervised by Luca De Feo and Kenneth Paterson. 2023.
  pdf

See also my page on teaching and community service.