epir

libepir - EllipticPIR client library

EllipticPIR is a private information retrieval (PIR) implementation backed by the EC-ElGamal encryption.

Try online WebAssembly demo: https://demo.ellipticpir.com/

This library contains cryptographic functions which are required to encrypt a query (a selector) to the EllipticPIR server and to decrypt a reply from the EllipticPIR server.

This repository provides native C library and bindings for C++, JavaScript and TypeScript programming languages.

C / C++

The C implementation has no runtime heap memory allocation. The C++ bindings is a header-only library.

Install

$ git clone https://github.com/EllipticPIR/libepir.git
$ cd libepir
$ mkdir build_c
$ cd build_c
$ cmake -DCMAKE_BUILD_TYPE=Release ..
$ make -j4  # (change the number "4" to your physical CPU cores to parallelize the build).
$ sudo make install

Generate mG.bin

$ epir_genm

Usage

Include epir.h (C) or epir.hpp (C++) in your source code.

For general usage, see ./src_c/bench_*.(c|cpp) files.

Node.js / TypeScript

This library both includes Node.js native addons (faster, no browser support) and WebAssembly builds (slower, browser support).

Install

npm

$ npm install epir

Build your own

$ git clone https://github.com/EllipticPIR/libepir.git
$ cd libepir
$ npm ci

Usage

See ./src_ts/types.ts for Node.js binding definitions.

For general usage, see files under the ./src_ts/__tests__ directory and ./pages/index.vue.

FAQs

What is mG.bin?

To decrypt a server's reply, you need to generate the mG.bin file. This file contains the pre-computation values of (G, 2*G, .., (0xFFFFFF)*G), where G is the generater of the Ed25519 curve.

To generate mG.bin, run

$ epir_genm

or

$ npm run epir_genm

The computation may take tens of seconds to finish. The computation time depends on the CPU power of your machine. (For comparison, on my desktop (Intel Core i7-7700K) it takes about ~15sec.)

The generated file will be located in $HOME/.EllipticPIR/mG.bin. The file size will be ~576MiB.

If you will not decrypt a server's reply, you can skip this step.