# Ferret: Fast Extension for Correlated OT with Small Communication

Kang Yang, Chenkai Weng, Xiao Lan, Jiang Zhang, Xiao Wang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

14 Scopus citations

## Abstract

Correlated oblivious transfer (COT) is a crucial building block for secure multi-party computation (MPC) and can be generated efficiently via OT extension. Recent works based on the pseudorandom correlation generator (PCG) paradigm presented a new way to generate random COT correlations using only communication sublinear to the output length. However, due to their high computational complexity, these protocols are only faster than the classical IKNP-style OT extension under restricted network bandwidth. In this paper, we propose new COT protocols in the PCG paradigm that achieve unprecedented performance. \em With $50$ Mbps network bandwidth, our maliciously secure protocol can produce one COT correlation in $22$ nanoseconds. More specifically, our results are summarized as follows: \beginenumerate \item We propose a semi-honest COT protocol with sublinear communication and linear computation. This protocol assumes primal-LPN and is built upon a recent VOLE protocol with semi-honest security by Schoppmann et al. (CCS 2019). We are able to apply various optimizations to reduce its communication cost by roughly $15\times$, not counting a one-time setup cost that diminishes as we generate more COT correlations. \item We strengthen our COT protocol to malicious security with no loss of efficiency. Among all optimizations, our new protocol features a new checking technique that ensures correctness and consistency essentially for free. In particular, our maliciously secure protocol is only \em $1-3$ nanoseconds slower for each COT. \item We implemented our protocols, and the code will be publicly available at EMP toolkit. We observe at least $9\times$ improvement in running time compared to the state-of-the-art protocol by Boyle et al. (CCS 2019) in both semi-honest and malicious settings under any network faster than $50$ Mbps. \endenumerate With this new record of efficiency for generating COT correlations, we anticipate new protocol designs and optimizations will flourish on top of our protocol.

Original language English (US) CCS 2020 - Proceedings of the 2020 ACM SIGSAC Conference on Computer and Communications Security Association for Computing Machinery 1607-1626 20 9781450370899 https://doi.org/10.1145/3372297.3417276 Published - Oct 30 2020 Yes 27th ACM SIGSAC Conference on Computer and Communications Security, CCS 2020 - Virtual, Online, United StatesDuration: Nov 9 2020 → Nov 13 2020

### Publication series

Name Proceedings of the ACM Conference on Computer and Communications Security 1543-7221

### Conference

Conference 27th ACM SIGSAC Conference on Computer and Communications Security, CCS 2020 United States Virtual, Online 11/9/20 → 11/13/20

## Keywords

• oblivious transfer
• secure computation

## ASJC Scopus subject areas

• Software
• Computer Networks and Communications

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