Pascal Reisert, Marc Rivinius, and Toomas Krips, and Ralf Küsters, “Arithmetic Tuples for MPC,” Cryptology ePrint Archive, Technical Report 2022/667, 2022.
Abstract
Some of the most efficient protocols for Multi-Party Computation (MPC) use a two-phase approach where correlated randomness, in particular Beaver triples, is generated in the offline phase and then used to speed up the online phase. Recently, more complex correlations have been introduced to optimize certain operations even further, such as matrix triples for matrix multiplications. In this paper, our goal is to speed up the evaluation of multivariate polynomials and therewith of whole arithmetic circuits in the online phase. To this end, we introduce a new form of correlated randomness: arithmetic tuples. Arithmetic tuples can be fine tuned in various ways to the constraints of application at hand, in terms of round complexity, bandwidth, and tuple size. We show that for many real-world setups an arithmetic tuples based online phase outperforms state-of-the-art protocols based on Beaver triples.BibTeX
Marc Rivinius, Pascal Reisert, Daniel Rausch, and Ralf Ralf Küsters, “Publicly Accountable Robust Multi-Party Computation,” in 43rd IEEE Symposium on Security and Privacy (S&P 2022), 2022.
Abstract
In recent years, lattice-based secure multi-party computation (MPC) has seen a rise in popularity and is used more and more in large scale applications like privacy-preserving cloud computing, electronic voting, or auctions. Many of these applications come with the following high security requirements: a computation result should be publicly verifiable, with everyone being able to identify a malicious party and hold it accountable, and a malicious party should not be able to corrupt the computation, force a protocol restart, or block honest parties or an honest third-party (client) that provided private inputs from receiving a correct result. The protocol should guarantee verifiability and accountability even if all protocol parties are malicious. While some protocols address one or two of these often essential security features, we present the first publicly verifiable and accountable, and (up to a threshold) robust SPDZ-like MPC protocol without restart. We propose protocols for accountable and robust online, offline, and setup computations. We adapt and partly extend the lattice-based commitment scheme by Baum et al. (SCN 2018) as well as other primitives like ZKPs. For the underlying commitment scheme and the underlying BGV encryption scheme we determine ideal parameters. We give a performance evaluation of our protocols and compare them to state-of-the-art protocols both with and without our target security features: public accountability, public verifiability and robustness.BibTeX
Marc Rivinius, Pascal Reisert, Daniel Rausch, and Ralf Küsters, “Publicly Accountable Robust Multi-Party Computation,” Cryptology ePrint Archive, Technical Report 2022/436, 2022.
Abstract
In recent years, lattice-based secure multi-party computation (MPC) has seen a rise in popularity and is used more and more in large scale applications like privacy-preserving cloud computing, electronic voting, or auctions. Many of these applications come with the following high security requirements: a computation result should be publicly verifiable, with everyone being able to identify a malicious party and hold it accountable, and a malicious party should not be able to corrupt the computation, force a protocol restart, or block honest parties or an honest third-party (client) that provided private inputs from receiving a correct result. The protocol should guarantee verifiability and accountability even if all protocol parties are malicious. While some protocols address one or two of these often essential security features, we present the first publicly verifiable and accountable, and (up to a threshold) robust SPDZ-like MPC protocol without restart. We propose protocols for accountable and robust online, offline, and setup computations. We adapt and partly extend the lattice-based commitment scheme by Baum et al. (SCN 2018) as well as other primitives like ZKPs. For the underlying commitment scheme and the underlying BGV encryption scheme we determine ideal parameters. We give a performance evaluation of our protocols and compare them to state-of-the-art protocols both with and without our target security features: public accountability, public verifiability and robustness.BibTeX
