Concretely Efficient Large-Scale MPC with Active Security (or, TinyKeys for TinyOT)
In this work we develop a new theory for concretely efficient, large-scale MPC with active security. Current practical techniques are mostly in the strong setting of all-but-one corruptions, which leads to protocols that scale badly with the number of par
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Bar-Ilan University, Ramat Gan, Israel [email protected] KU Leuven, imec-COSIC, Leuven, Belgium [email protected] 3 Aarhus University, Aarhus, Denmark [email protected] 4 University of Bristol, Bristol, UK [email protected]
Abstract. In this work we develop a new theory for concretely efficient, large-scale MPC with active security. Current practical techniques are mostly in the strong setting of all-but-one corruptions, which leads to protocols that scale badly with the number of parties. To work around this issue, we consider a large-scale scenario where a small minority out of many parties is honest and design scalable, more efficient MPC protocols for this setting. Our results are achieved by introducing new techniques for information-theoretic MACs with short keys and extending the work of Hazay et al. (CRYPTO 2018), which developed new passively secure MPC protocols in the same context. We further demonstrate the usefulness of this theory in practice by analyzing the concrete communication overhead of our protocols, which improve upon the most efficient previous works.
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Introduction
Secure multi-party computation (MPC) protocols allow a group of n parties to compute some function f on the parties’ private inputs, while preserving C. Hazay—Supported by the European Research Council under the ERC consolidators grant agreement n. 615172 (HIPS), and by the BIU Center for Research in Applied Cryptography and Cyber Security in conjunction with the Israel National Cyber Bureau in the Prime Minister’s Office. E. Orsini—Supported in part by ERC Advanced Grant ERC-2015-AdG-IMPaCT. P. Scholl—Supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 731583 (SODA), and the Danish Independent Research Council under Grant-ID DFF-6108-00169 (FoCC). E. Soria-Vazquez—Supported by the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 643161, and by ERC Advanced Grant ERC-2015-AdG-IMPaCT. c International Association for Cryptologic Research 2018 T. Peyrin and S. Galbraith (Eds.): ASIACRYPT 2018, LNCS 11274, pp. 86–117, 2018. https://doi.org/10.1007/978-3-030-03332-3_4
Concretely Efficient Large-Scale MPC with Active Security
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a number of security properties such as privacy and correctness. The former property implies data confidentiality, namely, nothing leaks from the protocol execution but the computed output. The latter requirement implies that the protocol enforces the integrity of the computations made by the parties, namely, honest parties are not led to accept a wrong output. Security is proven either in the presence of a passive adversary that follows the protocol specification but tries to learn more than allowed from its view of the protocol, or an active adversary that can arbitrarily deviate from the protocol specification in order to compromise the security of the other parties in the protocol. The past decade has seen huge progress in making MPC protocols communicat
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