## Cryptology ePrint Archive: Report 2017/214

Low Cost Constant Round MPC Combining BMR and Oblivious Transfer

Carmit Hazay and Peter Scholl and Eduardo Soria-Vazquez

Abstract: In this work, we present two new universally composable, actively secure, constant round multi-party protocols for generating BMR garbled circuits with free-XOR and reduced costs.

(1) Our first protocol takes a generic approach using any secret-sharing based MPC protocol for binary circuits, and a correlated oblivious transfer functionality.

(2) Our specialized protocol uses secret-sharing based MPC with information-theoretic MACs. This approach is less general, but requires no additional correlated OTs to compute the garbled circuit.

In both approaches, the underlying secret-sharing based protocol is only used for one secure $F_2$ multiplication per AND gate. An interesting consequence of this is that, with current techniques, constant round MPC for binary circuits is not much more expensive than practical, non-constant round protocols.

We demonstrate the practicality of our second protocol with an implementation, and perform experiments with up to $9$ parties securely computing the AES and SHA-256 circuits. Our running times improve upon the best possible performance with previous BMR-based protocols by 60 times.

Category / Keywords: cryptographic protocols /

Date: received 1 Mar 2017, last revised 19 May 2017

Contact author: eduardo soria-vazquez at bristol ac uk

Available format(s): PDF | BibTeX Citation

Note: Added implementation results, and various minor improvements.

Short URL: ia.cr/2017/214

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