### Stronger Notions and a More Efficient Construction of Threshold Ring Signatures

Alexander Munch-Hansen, Claudio Orlandi, and Sophia Yakoubov

##### Abstract

We consider threshold ring signatures (introduced by Bresson et al. [BSS02], where any t signers can sign a message while anonymizing themselves within a larger (size-n) group. The signature proves that t members of the group signed, without revealing anything else about their identities. Our contributions in this paper are two-fold. First, we strengthen existing definitions of threshold ring signatures in a natural way; we demand that a signer cannot be de-anonymized even by their fellow signers. This is crucial, since in applications where a signer's anonymity is important, we do not want anonymity to be compromised by a single insider. Our definitions demand non-interactive signing, which is important for anonymity, since truly anonymous interaction is difficult or impossible in many scenarios. Second, we give the first rigorous construction of a threshold ring signature with size independent of n, the number of users in the larger group. Instead, our signatures have size linear in t, the number of signers. This is also a very important contribution; signers should not have to choose between achieving their desired degree of anonymity (possibly very large n) and their need for communication efficiency.

Available format(s)
Category
Public-key cryptography
Publication info
Published elsewhere. MAJOR revision.LATINCRYPT 2021
DOI
10.1007/978-3-030-88238-9_18
Keywords
Threshold ring signaturesAnonymityUnique ring signaturesCompact signatures
Contact author(s)
almun @ cs au dk
orlandi @ cs au dk
sophia yakoubov @ cs au dk
History
2021-10-08: last of 2 revisions
See all versions
Short URL
https://ia.cr/2020/678

CC BY

BibTeX

@misc{cryptoeprint:2020/678,
author = {Alexander Munch-Hansen and Claudio Orlandi and Sophia Yakoubov},
title = {Stronger Notions and a More Efficient Construction of Threshold Ring Signatures},
howpublished = {Cryptology ePrint Archive, Paper 2020/678},
year = {2020},
doi = {10.1007/978-3-030-88238-9_18},
note = {\url{https://eprint.iacr.org/2020/678}},
url = {https://eprint.iacr.org/2020/678}
}

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