Paper 2025/041
Keyed-Verification Anonymous Credentials with Highly Efficient Partial Disclosure
Abstract
An anonymous credential (AC) system with partial disclosure allows users to prove possession of a credential issued by an issuer while selectively disclosing a subset of their attributes to a verifier in a privacy-preserving manner. In keyed-verification AC (KVAC) systems, the issuer and verifier share a secret key. Existing KVAC schemes rely on computationally expensive zero-knowledge proofs during credential presentation, with the presentation size growing linearly with the number of attributes. In this work, we propose two highly efficient KVAC constructions that eliminate the need for zero-knowledge proofs during the credential presentation and achieve constant-size presentations.
Our first construction adapts the approach of Fuchsbauer et al. (JoC'19), which achieved constant-size credential presentation in a publicly verifiable setting using their proposed structure-preserving signatures on equivalence classes (SPS-EQ) and set commitment schemes, to the KVAC setting. We introduce structure-preserving message authentication codes on equivalence classes (SP-MAC-EQ) and designated-verifier set commitments (DVSC), resulting in a KVAC system with constant-size credentials (2 group elements) and presentations (4 group elements). To avoid the bilinear groups and pairing operations required by SP-MAC-EQ, our second construction uses a homomorphic MAC with a simplified DVSC. While this sacrifices constant-size credentials (
Metadata
- Available format(s)
-
PDF
- Category
- Cryptographic protocols
- Publication info
- Preprint.
- Keywords
- KVACSP-MAC-EQDesignated-Verifier Set CommitmentNon-Interactive Zero-Knowledge Proofs
- Contact author(s)
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omid mirzamohammadi @ esat kuleuven be
jan bobolz @ ed ac uk
ssedagha @ esat kuleuven be
emad heydaribeni @ kuleuven be
aabidin @ esat kuleuven be
dave singelee @ esat kuleuven be
bart preneel @ esat kuleuven be - History
- 2025-01-13: approved
- 2025-01-10: received
- See all versions
- Short URL
- https://ia.cr/2025/041
- License
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CC BY
BibTeX
@misc{cryptoeprint:2025/041, author = {Omid Mirzamohammadi and Jan Bobolz and Mahdi Sedaghat and Emad Heydari Beni and Aysajan Abidin and Dave Singelee and Bart Preneel}, title = {Keyed-Verification Anonymous Credentials with Highly Efficient Partial Disclosure}, howpublished = {Cryptology {ePrint} Archive, Paper 2025/041}, year = {2025}, url = {https://eprint.iacr.org/2025/041} }