### Traceable Constant-Size Multi-Authority Credentials

Chloé Hébant and David Pointcheval

##### Abstract

Many attribute-based anonymous credential (ABC) schemes have been proposed allowing a user to prove the possession of some attributes, anonymously. They became more and more practical with, for the most recent papers, a constant-size credential to show a subset of attributes issued by a unique credential issuer. However, proving possession of attributes coming from $K$ different credential issuers usually requires $K$ independent credentials to be shown. Only attribute-based credential schemes from aggregatable signatures can overcome this issue. In this paper, we propose new ABC schemes from aggregatable signatures with randomizable tags. We consider malicious credential issuers, with adaptive corruptions and collusions with malicious users. Whereas our constructions only support selective disclosures of attributes, to remain compact, our approach significantly improves the complexity in both time and memory of the showing of multiple attributes: for the first time, the cost for the prover is (almost) independent of the number of attributes and the number of credential issuers. Whereas anonymous credentials require privacy of the user, we propose the first schemes allowing traceability. We formally define an aggregatable signature scheme with (traceable) randomizable tags, which is of independent interest. We build concrete schemes from the recent linearly homomorphic signature scheme of PKC 20. As all the recent ABC schemes, our construction relies on signatures which unforgeability is proven in the bilinear generic group model.

Available format(s)
Category
Cryptographic protocols
Publication info
Preprint. MINOR revision.
Keywords
Anonymous credentialsaggregatable signaturestraceability
Contact author(s)
chloe hebant @ ens fr
History
2021-09-28: last of 2 revisions
See all versions
Short URL
https://ia.cr/2020/657

CC BY

BibTeX

@misc{cryptoeprint:2020/657,
author = {Chloé Hébant and David Pointcheval},
title = {Traceable Constant-Size Multi-Authority Credentials},
howpublished = {Cryptology ePrint Archive, Paper 2020/657},
year = {2020},
note = {\url{https://eprint.iacr.org/2020/657}},
url = {https://eprint.iacr.org/2020/657}
}

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