Cryptology ePrint Archive: Report 2015/901

A Unified Approach to MPC with Preprocessing using OT

Tore Kasper Frederiksen and Marcel Keller and Emmanuela Orsini and Peter Scholl

Abstract: 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.

Category / Keywords: cryptographic protocols / MPC, SPDZ, TinyOT, MiniMAC, Preprocessing, OT extension

Original Publication (with major differences): IACR-ASIACRYPT-2015

Date: received 16 Sep 2015, last revised 16 Sep 2015

Contact author: Emmanuela Orsini at bristol ac uk; peter scholl at bristol ac uk; m keller@bristol ac uk; jot2re@cs au dk

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Version: 20150916:170615 (All versions of this report)

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