libOTe

A fast and portable C++11 library for Oblivious Transfer extension (OTe). The primary design goal of this library to obtain high performance while being easy to use. This library currently implements:

The semi-honest 1-out-of-2 OT [IKNP03].
The semi-honest 1-out-of-N OT [KKRT16].
The malicious secure 1-out-of-2 OT [KOS15].
The malicious secure 1-out-of-2 Delta-OT [KOS15],[BLNNOOSS15].
The malicious secure 1-out-of-N OT [OOS16].
The malicious secure approximate K-out-of-N OT [RR16].
The malicious secure 1-out-of-2 base OT [NP00].

Introduction

This library provides several different classes of OT protocols. First is the base OT protocol of Naor Prinkas [NP00]. This protocol bootstraps all the other OT extension protocols. Within the OT extension protocols, we have 1-out-of-2, 1-out-of-N and ~K-out-of-N, both in the semi-honest and malicious settings.

All implementations are highly optimized using fast SSE instructions and vectorization to obtain optimal performance both in the single and multi-threaded setting. See the Performance section for a comparison between protocols and to other libraries.

Performance

The running time in seconds for computing n=2²⁴ OTs on a single Intel Xeon server (2 36-cores Intel Xeon CPU E5-2699 v3 @ 2.30GHz and 256GB of RAM) as of 11/16/2016. All timings shown reflect a "single" thread per party, with the expection that network IO in libOTe is performed in the background by a separate thread.

Type	Security	Protocol	libOTe (SHA1/AES)	Encrypto Group (SHA256)	Apricot (AES-hash)	OOS16 (blake2)	emp-toolkit (AES-hash)
1-out-of-N (N=2⁷⁶)	malicious	OOS16	11.7 / 9.2	~	~	24**	~
1-out-of-N (N=2¹²⁸)	passive	KKRT16	9.2 / 6.7	~	~	~	~
1-out-of-2 Delta-OT	malicious	KOS15	2.1*	~	~	~	~
1-out-of-2	malicious	ALSZ15	~	17.3	~	~	10
1-out-of-2	malicious	KOS15	3.9 / 0.7	~	1.1	~	2.9
1-out-of-2	passive	IKNP03	3.7 / 0.6	11.3	0.6	~	2.7

* Delta-OT does not use the SHA1 or AES hash function.

** This timing was taken from the [OOS16] paper and their implementation used multiple threads. The number was not specified. When using the libOTe implementation with multiple threads, a timing of 2.6 seconds was obtained with the SHA1 hash function.

It should be noted that the libOTe implementation uses the Boost ASIO library to perform more efficient asynchronous network IO. This involves using a background thread to help process network data. As such, this is not a completely fair comparison to the Apricot implementation but we don't expect it to have a large impact. It also appears that the Encrypto Group implementation uses asynchronous network IO.

The above timings were obtained with the follwoing options:

1-out-of-2 malicious:

Apricot: ./ot.x -n 16777216 -p 0 -m a -l 100 & ./ot.x -p 1 -m a -n 16777216 -l 100
Encrypto Group: ./ot.exe -r 0 -n 16777216 -o 1 & ./ot.exe -r 1 -n 16777216 -o 1
emp-toolkit: 2x 2²³ ./mot 0 1212 & ./mot 1 1212

1-out-of-2 semi-honest:

Apricot: ./ot.x -n 16777216 -p 0 -m a -l 100 -pas & ./ot.x -p 1 -m a -n 16777216 -l 100 -pas
Encrypto Group: ./ot.exe -r 0 -n 16777216 -o 0 & ./ot.exe -r 1 -n 16777216 -o 0
emp-toolkit: 2*2²³ ./shot 0 1212 & ./shot 1 1212

License

This project has been placed in the public domain. As such, you are unrestricted in how you use it, commercial or otherwise. However, no warranty of fitness is provided. If you found this project helpful, feel free to spread the word and cite us.

Install

The library is cross platform and has been tested on both Windows and Linux. The library should work on MAC but it has not been tested. There are two library dependencies including Boost (networking), and Miracl (Base OT). For each, we provide a script that automates the download and build steps. The version of Miracl used by this library requires specific configuration and therefore we advise using the coned repository that we provide.

Windows

In Powershell, this will set up the project

git clone --recursive https://github.com/osu-crypto/libOTe.git
cd libOTe/thirdparty/win
getBoost.ps1; getMiracl.ps1
cd ../..
libOTe.sln

Requirements: Powershell, Powershell Set-ExecutionPolicy Unrestricted, Visual Studio 2015, CPU supporting PCLMUL, AES-NI, and SSE4.1. Optional: nasm for improved SHA1 performance.

Build the solution within visual studio or with MSBuild. To see all the command line options, execute the program

frontend.exe

If the cryptoTools directory is empty git submodule update --init --recursive.

IMPORTANT: By default, the build system needs the NASM compiler to be located at C:\NASM\nasm.exe. In the event that it isn't, there are two options, install it, or enable the pure c++ implementation. The latter option is done by excluding libOTe/Crypto/asm/sha_win64.asm from the build system and undefining INTEL_ASM_SHA1 on line 28 of libOTe/Crypto/sha1.cpp.

Linux

In short, this will build the project

git clone --recursive https://github.com/osu-crypto/libOTe.git
cd libOTe/thirdparty/linux
bash all.get
cd ../..
CMake  -G "Unix Makefiles"
make

Requirements: CMake, Make, g++ or similar, CPU supporting PCLMUL, AES-NI, and SSE4.1. Optional: nasm for improved SHA1 performance.

The libraries will be placed in libOTe/lib and the binary frontend.exe will be placed in libOTe/bin To see all the command line options, execute the program

./bin/frontend.exe

Note: In the case that miracl or boost is already installed, the steps cd libOTe/thirdparty/linux; bash all.get can be skipped and CMake will attempt to find them instead. Boost is found with the CMake findBoost package and miracl is found with the find_library(miracl) command.

If the cryptoTools directory is empty git submodule update --init --recursive.

Citing

Spread the word!

@misc{libOTe,
    author = {Peter Rindal},
    title = {{libOTe: an efficient, portable, and easy to use Oblivious Transfer Library}},
    howpublished = {\url{https://github.com/osu-crypto/libOTe}},
}

Protocol Details

The 1-out-of-N [OOS16] protocol currently is set to work forn N=2⁷⁶ but is capable of supporting arbitrary codes given the generator matrix in text format. See ./libOTe/Tools/Bch511.txt for an example.

The 1-out-of-N [KKRT16] for arbitrary N is also implemented and slightly faster than [OOS16]. However, [KKRT16] is in the semi-honest setting.

The approximate K-out-of-N OT [RR16] protocol is also implemented. This protocol allows for a rough bound on the value K with a very light weight cut and choose technique. It was introduced for a PSI protocol that builds on a Garbled Bloom Filter.

Help

Contact Peter Rindal rindalp@oregonstate.edu for any assistance on building or running the library.

Citation

[IKNP03] - Yuval Ishai and Joe Kilian and Kobbi Nissim and Erez Petrank, Extending Oblivious Transfers Efficiently.

[KOS15] - Marcel Keller and Emmanuela Orsini and Peter Scholl, Actively Secure OT Extension with Optimal Overhead. eprint/2015/546

[OOS16] - Michele Orrù and Emmanuela Orsini and Peter Scholl, Actively Secure 1-out-of-N OT Extension with Application to Private Set Intersection. eprint/2016/933

[KKRT16] - Vladimir Kolesnikov and Ranjit Kumaresan and Mike Rosulek and Ni Trieu, Efficient Batched Oblivious PRF with Applications to Private Set Intersection. eprint/2016/799

[RR16] - Peter Rindal and Mike Rosulek, Improved Private Set Intersection against Malicious Adversaries. eprint/2016/746

[BLNNOOSS15] - Sai Sheshank Burra and Enrique Larraia and Jesper Buus Nielsen and Peter Sebastian Nordholt and Claudio Orlandi and Emmanuela Orsini and Peter Scholl and Nigel P. Smart, High Performance Multi-Party Computation for Binary Circuits Based on Oblivious Transfe. eprint/2015/472

[ALSZ15] - Gilad Asharov and Yehuda Lindell and Thomas Schneider and Michael Zohner, More Efficient Oblivious Transfer Extensions with Security for Malicious Adversaries. eprint/2015/061

[NP00] - Moni Naor, Benny Pinkas, Efficient Oblivious Transfer Protocols.

RobTrifiletti / libOTe