Sovereign Modal Signatures

Yan Y, Tang KH, Chu H, Chow SS, Ling S, Wang H, Zhang K (2027)

Publication Type: Conference contribution

Publication year: 2027

Journal

Lecture Notes in Computer Science Springer Verlag

Publisher: Springer Science and Business Media Deutschland GmbH

Book Volume: 16571 LNCS

Pages Range: 444-472

Conference Proceedings Title: Lecture Notes in Computer Science

Event location: Stony Brook, WI, USA

ISBN: 9783032325594

DOI: 10.1007/978-3-032-32560-0_16

Abstract

Signing anonymously under both hidden and public policies with per-signature accountability has only been studied piecemeal, as prior schemes address at most one dimension or restrict function classes. Here, we introduce sovereign modal signatures, the first scheme unifying both dimensions with support for hidden-circuit evaluation over bounded-size arithmetic circuits without universal circuits. Each signer holds a private attribute and a hidden policy F, certified by an authority and concealed from signatures. Resting on a public combiner P, the signing process maps the joint outputs of F and an ad hoc function G to a derived message and an opening tag governing per-signature traceability. Modifying the effective policy at signing time requires no key reissuance, since G is chosen freshly against the fixed F. Achieving zero-knowledge evaluation of F without exposing its structure is our core challenge, resolved by treating F’s PLONK description as witness rather than statement. No universal circuits are required: our reduction yields a fixed verification circuit of size linear in F’s gate count; the resulting scheme is provably secure in the random oracle model. Concretely, our generic construction needs only signatures, public-key encryption, and non-interactive zero-knowledge arguments of knowledge for arithmetic circuits. Hidden arithmetic circuits over any finite field are fully supported, subsuming the restricted Boolean and linear function classes of prior hidden-function schemes. Our post-quantum instantiation combines ZKBoo (Usenix Security ’16) under the MPC-in-the-Head (MPCitH, STOC ’07) paradigm with lattice-based primitives over Zq, achieving plausibly post-quantum security without pairings or the algebraic group model. With proof sizes quasilinear in F’s gate count and linear in G and P’s multiplications, the scheme also readily admits richer MPCitH instantiations.

Involved external institutions

National University of Singapore (NUS) SG Singapore (SG) Technische Universität Wien / Vienna University of Technology AT Austria (AT) Shaanxi Normal University (SNNU) / 陕西师范大学 CN China (CN) University of Clermont Auvergne FR France (FR) The Chinese University of Hong Kong (CUHK) CN China (CN)

How to cite

APA:

Yan, Y., Tang, K.H., Chu, H., Chow, S.S., Ling, S., Wang, H., & Zhang, K. (2027). Sovereign Modal Signatures. In Kangkook Jee, Aniket Kate (Eds.), Lecture Notes in Computer Science (pp. 444-472). Stony Brook, WI, USA: Springer Science and Business Media Deutschland GmbH.

MLA:

Yan, Yingfei, et al. "Sovereign Modal Signatures." Proceedings of the 24th International Conference on Applied Cryptography and Network Security, ACNS 2026, Stony Brook, WI, USA Ed. Kangkook Jee, Aniket Kate, Springer Science and Business Media Deutschland GmbH, 2027. 444-472.

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