Paper 2022/1437

Secure Multiparty Computation from Threshold Encryption based on Class Groups

Lennart Braun, Aarhus University
Ivan Damgård, Aarhus University
Claudio Orlandi, Aarhus University

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 then show how to use our threshold scheme to achieve general secure multiparty computation (MPC) with only transparent set-up, i.e., with no secret trapdoors involved. To achieve this, we also design a new zero-knowledge protocol for proving multiplicative relations between encrypted values. As a result, the zero-knowledge proofs needed to get active security add only a constant factor overhead. Finally, we explain how to 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.

Available format(s)
Cryptographic protocols
Publication info
mpc zero-knowledge threshold encryption class groups
Contact author(s)
braun @ cs au dk
ivan @ cs au dk
orlandi @ cs au dk
2022-10-24: approved
2022-10-21: received
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Creative Commons Attribution


      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},
      note = {\url{}},
      url = {}
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