Paper 2022/1437
Secure Multiparty Computation from Threshold Encryption Based on Class Groups
, Aarhus University, Aarhus University, Aarhus UniversityAbstract
We construct the first actively-secure threshold version of the cryptosystem based on class groups from the so-called CL~framework (Castagnos and Laguillaumie, 2015). We show how to use our threshold scheme to achieve general universally composable (UC) secure multiparty computation (MPC) with only transparent set-up, i.e., with no secret trapdoors involved. On the way to our goal, we design new zero-knowledge (ZK) protocols with constant communication complexity for proving multiplicative relations between encrypted values. This allows us to use the ZK proofs to achieve MPC with active security with only a constant factor overhead. Finally, we adapt our protocol for the so-called "You-Only-Speak-Once" (YOSO) setting, which is a very promising recent approach for performing MPC over a blockchain. This is possible because our key generation protocol is simpler and requires significantly less interaction compared to previous approaches: in particular, our new key generation protocol allows the adversary to bias the public key, but we show that this has no impact on the security of the resulting cryptosystem.
Note: Added a note regarding the usage of our zero-knowledge proofs under the rough-order assumption. For more details see ePrint 2024/717.
Metadata
- Available format(s)
-
PDF
- Category
- Cryptographic protocols
- Publication info
- A major revision of an IACR publication in CRYPTO 2023
- DOI
- 10.1007/978-3-031-38557-5_20
- Keywords
- mpczero-knowledgethreshold encryptionclass groups
- Contact author(s)
-
braun @ cs au dk
ivan @ cs au dk
orlandi @ cs au dk - History
- 2024-05-10: last of 4 revisions
- 2022-10-21: received
- See all versions
- Short URL
- https://ia.cr/2022/1437
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2022/1437,
author = {Lennart Braun and Ivan Damgård and Claudio Orlandi},
title = {Secure Multiparty Computation from Threshold Encryption Based on Class Groups},
howpublished = {Cryptology ePrint Archive, Paper 2022/1437},
year = {2022},
doi = {10.1007/978-3-031-38557-5_20},
note = {\url{https://eprint.iacr.org/2022/1437}},
url = {https://eprint.iacr.org/2022/1437}
}
