## A unified approach to MPC with preprocessing using OT.(English)Zbl 1396.94077

Iwata, Tetsu (ed.) et al., Advances in cryptology – ASIACRYPT 2015. 21st international conference on the theory and application of cryptology and information security, Auckland, New Zealand, November 29 – December 3, 2015. Proceedings. Part I. Berlin: Springer (ISBN 978-3-662-48796-9/pbk; 978-3-662-48797-6/ebook). Lecture Notes in Computer Science 9452, 711-735 (2015).
Summary: SPDZ, TinyOT and MiniMAC are a family of MPC protocols based on secret sharing with MACs, where a preprocessing stage produces multiplication triples in a finite field. This work describes new protocols for generating multiplication triples in fields of characteristic two using OT extensions. Before this work, TinyOT, which works on binary circuits, was the only protocol in this family using OT extensions. Previous SPDZ protocols for triples in large finite fields require somewhat homomorphic encryption, which leads to very inefficient runtimes in practice, while no dedicated preprocessing protocol for MiniMAC (which operates on vectors of small field elements) was previously known. Since actively secure OT extensions can be performed very efficiently using only symmetric primitives, it is highly desirable to base MPC protocols on these rather than expensive public key primitives. We analyze the practical efficiency of our protocols, showing that they should all perform favorably compared with previous works; we estimate our protocol for SPDZ triples in $$\mathbb {F}_{2^{40}}$$ will perform around 2 orders of magnitude faster than the best known previous protocol.
For the entire collection see [Zbl 1334.94027].

### MSC:

 94A60 Cryptography

### Keywords:

MPC; SPDZ; TinyOT; MiniMAC; preprocessing; OT extension
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