Revisiting Keyed-Verification Anonymous Credentials

Michele Orrù

Paper 2024/1552

Revisiting Keyed-Verification Anonymous Credentials

Michele Orrù

, Centre National de la Recherche Scientifique

Abstract

Keyed-verification anonymous credentials are widely recognized as among the most efficient tools for anonymous authentication. In this work, we revisit two prominent credential systems: the scheme by Chase et al. (CCS 2014), commonly referred to as CMZ or PS MAC, and the scheme by Barki et al. (SAC 2016), known as BBDT or BBS MAC. We show how to make CMZ statistically anonymous and BBDT compatible with the BBS RFC draft. We provide a comprehensive security analysis for strong(er) properties of unforgeability and anonymity. These properties allow them to be composed with extensions that users can pick and choose. We show that simpler variants satisfying one-more unforgeability can still be anonymous tokens (Kreuter et al., CRYPTO 2020). To enable faster proofs for complex presentations, we present a compiler that uses an interactive oracle proof and a designated-verifier polynomial commitment to construct a designated-verifier non-interactive argument. For keyed-verification anonymous credentials, designated-verifier proofs suffice since the verifier is known in advance. We explore extensions that could benefit from this approach.

Note: Preprint.

Metadata

Available format(s): PDF
Category: Cryptographic protocols
Publication info: Preprint.
Keywords: polynomial commitments algebraic MACs succinct arguments anonymous credentials identity protocols
Contact author(s): m @ orru net
History: 2024-10-04: approved; 2024-10-03: received; See all versions
Short URL: https://ia.cr/2024/1552
License: CC0

BibTeX

@misc{cryptoeprint:2024/1552,
      author = {Michele Orrù},
      title = {Revisiting Keyed-Verification Anonymous Credentials},
      howpublished = {Cryptology {ePrint} Archive, Paper 2024/1552},
      year = {2024},
      url = {https://eprint.iacr.org/2024/1552}
}