Paper 2022/661

Protego: A Credential Scheme for Permissioned Blockchains (Extended Version)

Aisling Connolly, DFINITY
Jerome Deschamps, LIMOS, University Clermont Auvergne, France
Pascal Lafourcade, LIMOS, University Clermont Auvergne, France
Octavio Perez Kempner, DIENS, École normale supérieure, CNRS, PSL University, Paris, France, be-ys Research, France

Recent works to improve privacy and auditability in permissioned blockchains like Hyperledger Fabric rely on Idemix, the only anonymous credential system that has been integrated to date. The current Idemix implementation in Hyperledger Fabric (v2.4) only supports a fixed set of attributes, it does not support revocation features, nor does it support anonymous endorsement of transactions (in Fabric, transactions need to be approved by a subset of peers before consensus). A prototype Idemix extension by Bogatov et al. (CANS, 2021) was proposed to include revocation, auditability, and to gain privacy for users. We explore how to gain efficiency, functionality, and further privacy departing from recent works on anonymous credentials based on Structure-Preserving Signatures on Equivalence Classes. As a result, we propose Protego and Protego Duo, two alternatives for Idemix and its recent extensions. We discuss how they can be used in the permissioned blockchain setting and integrated to Hyperledger Fabric. We also provide a prototype implementation and benchmarks showing that both alternatives are twice as fast as state-of-the-art-approaches.

Note: Updated values for Protego Duo in Table 1

Available format(s)
Cryptographic protocols
Publication info
anonymous credentials auditability Hyperledger Fabric mercurial signatures permissioned blockchains SPS-EQ
Contact author(s)
aislingmconnolly @ gmail com
jerome deschamps @ etu uca fr
pascal lafourcade @ uca fr
octavio perez kempner @ ens fr
2022-06-06: last of 2 revisions
2022-05-27: received
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Creative Commons Attribution


      author = {Aisling Connolly and Jerome Deschamps and Pascal Lafourcade and Octavio Perez Kempner},
      title = {Protego: A Credential Scheme for Permissioned Blockchains (Extended Version)},
      howpublished = {Cryptology ePrint Archive, Paper 2022/661},
      year = {2022},
      note = {\url{}},
      url = {}
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