### Fast Threshold ECDSA with Honest Majority

Ivan Damgård, Thomas Pelle Jakobsen, Jesper Buus Nielsen, Jakob Illeborg Pagter, and Michael Bæksvang Østergård

##### Abstract

ECDSA is a widely adopted digital signature standard. A number of threshold protocols for ECDSA have been developed that let a set of parties jointly generate the secret signing key and compute signatures, without ever revealing the signing key. Threshold protocols for ECDSA have seen recent interest, in particular due to the need for additional security in cryptocurrency wallets where leakage of the signing key is equivalent to an immediate loss of money. We propose a threshold ECDSA protocol secure against an active adversary in the honest majority model with abort. Our protocol is efficient in terms of both computation and bandwidth usage, and it allows the parties to pre-process parts of the signature, such that once the message to sign becomes known, they can compute a secret sharing of the signature very efficiently, using only local operations. We also show how to obtain fairness in the online phase at the cost of some additional work in the pre-processing, i.e., such that the protocol either aborts during the pre-processing phase, in which case nothing is revealed, or the signature is guaranteed to be delivered to all honest parties.

Available format(s)
Category
Cryptographic protocols
Publication info
Preprint. MINOR revision.
Keywords
ECDSAsignaturesthreshold cryptographydistributed cryptography
Contact author(s)
tpj @ sepior com
jbn @ cs au dk
History
2020-05-04: revised
See all versions
Short URL
https://ia.cr/2020/501

CC BY

BibTeX

@misc{cryptoeprint:2020/501,
author = {Ivan Damgård and Thomas Pelle Jakobsen and Jesper Buus Nielsen and Jakob Illeborg Pagter and Michael Bæksvang Østergård},
title = {Fast Threshold ECDSA with Honest Majority},
howpublished = {Cryptology ePrint Archive, Paper 2020/501},
year = {2020},
note = {\url{https://eprint.iacr.org/2020/501}},
url = {https://eprint.iacr.org/2020/501}
}

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