Cryptology ePrint Archive: Report 2014/468

Privacy-Preserving Auditing for Attribute-Based Credentials

Jan Camenisch, Anja Lehmann, Gregory Neven, Alfredo Rial

Abstract: Privacy-enhancing attribute-based credentials (PABCs) allow users to authenticate to verifiers in a data-minimizing way, in the sense that users are unlinkable between authentications and only disclose those attributes from their credentials that are relevant to the verifier. We propose a practical scheme to apply the same data minimization principle when the verifiers’ authentication logs are subjected to external audits. Namely, we propose an extended PABC scheme where the verifier can further remove attributes from presentation tokens before handing them to an auditor, while preserving the verifiability of the audited tokens. We present a generic construction based on a signature, a signature of knowledge and a trapdoor commitment scheme, prove it secure in the universal composability framework, and give efficient instantiations based on the strong RSA and Decision Composite Residuosity (DCR) assumptions in the random-oracle model.

Category / Keywords: cryptographic protocols / privacy-enhancing credentials, data minimization, auditing

Original Publication (with major differences): ESORICS 2014

Date: received 16 Jun 2014

Contact author: anj at zurich ibm com

Available format(s): PDF | BibTeX Citation

Version: 20140621:045330 (All versions of this report)

Short URL: ia.cr/2014/468

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