eprint.iacr.orgpaper

Hide Now, Trace Later: Retrospective Attribution in Issuer-Hiding Credentials

Krenn, Lesaignoux, Mir and Spini (AIT Austrian Institute of Technology) propose an "issuer inspection" mechanism for issuer-hiding attribute-based credentials (ABCs): an inspection authority can release time-bound keys that let verifiers locally flag presentations tied to a specific compromised issuer without unmasking other issuers or periods. They formalize the syntax/security model, give a generic construction, and instantiate it concretely using Groth's randomizable structure-preserving signatures, Schnorr-style proofs, and an adapted Gentry anonymous identity-based encryption scheme, showing the overhead stays practical. This addresses the accountability gap introduced when issuer-hiding ABCs conceal which authority issued a credential during verification.