Tanuki: Two-round Threshold Signatures from Lattices

"Preview Talk" (by Team Tanuki) @ MPTS 2026, in reply to the NIST Threshold Call

Abstract: In this presentation, we give an overview of our lattice-based threshold signature scheme, which features a two-round signing protocol with preprocessing, compact signatures and verification keys, and unforgeability against a dishonest majority in the random oracle model. The scheme scales to up to 1024 signers and produces Raccoon-compatible signatures. From a design perspective, Tanuki can be viewed as a synthesis of two previously proposed schemes in the literature: Espitau–Katsumata–Takemure (CRYPTO ’24) and Ringtail (S&P ’25).

Joint work: Cecilia Boschini, Thomas Espitau, Aaron Kaiser, Shuichi Katsumata, Darya Kaviani, Russell W.F. Lai, Giulio Malavolta, Thomas Prest, Peter Schwabe, Akira Takahashi, Kaoru Takemure, Mehdi Tibouchi.

[Slides] Suggested readings:

• Preview Writeup: Tanuki: Two-round Threshold Signatures from Lattices
• "Two-Round Threshold Signature from Algebraic One-More Learning with Errors” (ia.cr/2024/496)
• "Ringtail: Practical Two-Round Threshold Signatures from Learning with Errors” (ia.cr/2024/1113)