Biscuit: New MPCitH Signature Scheme from Structured Multivariate Polynomials

Luk Bettale (1) , Delaram Kahrobaei (2) , Ludovic Perret (3) , Javier Verbel (4)

1 Idemia
2 QC - Queens College [CUNY]
3 PolSys - Polynomial Systems
4 TII - Technology Innovation Institute

This paper describes Biscuit, a new multivariate-based signature scheme derived using the MPCitH approach. The security of Biscuit is related to the problem of solving a set of quadratic structured systems of algebraic equations. These equations are highly compact and can be evaluated using very few multiplications. The core of Biscuit is a rather simple MPC protocol which consists of the parallel execution of a few secure multiplications using standard optimized multiplicative triples. This paper also includes several improvements with respect to Biscuit submission to the last NIST PQC standardization process for additional signature schemes. Notably, we introduce a new hypercube variant of Biscuit, refine the security analysis with recent third-party attacks, and present a new avx2 implementation of Biscuit.

Mots clés: Post-Quantum Digital Signature MPC-in-the-Head Multivariate Polynomials; Post-Quantum; Digital Signature; MPC-in-the-Head; Multivariate Polynomials

Domaines: Cryptographie et sécurité [cs.CR]

Luk Bettale, Delaram Kahrobaei, Ludovic Perret, Javier Verbel. Biscuit: New MPCitH Signature Scheme from Structured Multivariate Polynomials. Applied Cryptography and Network Security (ACNS), Mar 2024, Abu Dhabi, United Arab Emirates. pp.457-486, ⟨10.1007/978-3-031-54770-6_18⟩. ⟨hal-04293399⟩