Paper 2019/035

Using TopGear in Overdrive: A more efficient ZKPoK for SPDZ

Carsten Baum, Daniele Cozzo, and Nigel P. Smart


The HighGear protocol (Eurocrypt 2018) is the fastest currently known approach to preprocessing for the SPDZ Multi-Party Computation scheme. Its backbone is formed by an Ideal Lattice-based Somewhat Homomorphic Encryption Scheme and accompanying Zero-Knowledge proofs. Unfortunately, due to certain characteristics of HighGear such current implementations use far too low security parameters in a number of places. This is mainly due to memory and bandwidth consumption constraints. In this work we present a new approach to the ZKPoKs as introduced in the HighGear work. We rigorously formalize their approach and show how to improve upon it using a different proof strategy. This allows us to increase the security of the underlying protocols, all while maintaining roughly the same performance in terms of memory and bandwidth consumption.

Note: Minor correction

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Minor revision. To appear SAC 2019
Contact author(s)
nigel smart @ kuleuven be
daniele cozzo @ kuleuven be
carsten baum @ biu ac il
2020-03-19: last of 4 revisions
2019-01-17: received
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Creative Commons Attribution


      author = {Carsten Baum and Daniele Cozzo and Nigel P.  Smart},
      title = {Using TopGear in Overdrive: A more efficient ZKPoK for SPDZ},
      howpublished = {Cryptology ePrint Archive, Paper 2019/035},
      year = {2019},
      note = {\url{}},
      url = {}
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