PAPR: Publicly Auditable Privacy Revocation for Anonymous Credentials

Joakim Brorsson, Bernardo David, Lorenzo Gentile, Elena Pagnin, Paul Stankovski Wagner

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceedingpeer-review


We study the notion of anonymous credentials with Publicly Auditable Privacy Revocation (PAPR). PAPR credentials simultaneously provide conditional user privacy and auditable privacy revocation. The first property implies that users keep their identity private when authenticating unless and until an appointed authority requests to revoke this privacy, retroactively. The second property enforces that auditors can verify whether or not this authority has revoked privacy from an issued credential (i.e. learned the identity of the user who owns that credential), holding the authority accountable. In other words, the second property enriches conditionally anonymous credential systems with transparency by design, effectively discouraging such systems from being used for mass surveillance. In this work, we introduce the notion of a PAPR anonymous credential scheme, formalize it as an ideal functionality, and present constructions that are provably secure under standard assumptions in the Universal Composability framework. The core tool in our PAPR construction is a mechanism for randomly selecting an anonymous committee which users secret share their identity information towards, while hiding the identities of the committee members from the authority. As a consequence, in order to initiate the revocation process for a given credential, the authority is forced to post a request on a public bulletin board used as a broadcast channel to contact the anonymous committee that holds the keys needed to decrypt the identity connected to the credential. This mechanism makes the user de-anonymization publicly auditable.

Original languageEnglish
Title of host publicationTopics in Cryptology – CT-RSA 2023 - Cryptographers’ Track at the RSA Conference 2023, Proceedings
EditorsMike Rosulek
PublisherSpringer Science and Business Media B.V.
Number of pages28
ISBN (Print)9783031308710
Publication statusPublished - 2023
EventCryptographers’ Track at the RSA Conference, CT-RSA 2023 - San Francisco, United States
Duration: 2023 Apr 242023 Apr 27

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume13871 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


ConferenceCryptographers’ Track at the RSA Conference, CT-RSA 2023
Country/TerritoryUnited States
CitySan Francisco

Subject classification (UKÄ)

  • Computer Science


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