vdf-rs — Verifiable Delay Function (VDF) in Rust

Maintained fork of poanetwork/vdf. The original vdf crate on crates.io is unmaintained; this project publishes the library as vdf-rs.

What is a VDF?

A Verifiable Delay Function (VDF) is a function that requires substantial time to evaluate (even with a polynomial number of parallel processors) but can be very quickly verified as correct. VDFs can be used to construct randomness beacons with multiple applications in a distributed network environment. By introducing a time delay during evaluation, VDFs prevent malicious actors from influencing output. The output cannot be differentiated from a random number until the final result is computed. See https://eprint.iacr.org/2018/712.pdf for more details.

Description

This VDF implementation is written in Rust. The GMP library is used for arithmetic and greatest common divisor (GCD) calculations. We use class groups to implement the approaches described in the following papers:

Simple Verifiable Delay Functions. Pietrzak, 2018
Efficient Verifiable Delay Functions. Wesolowski, 2018

The chosen generator is (2, 1, c), where c is calculated from the provided discriminant. A form is represented internally (a, b, c), with the discriminant not being used in most computations. This implementation performs reduction after every multiplication and squaring, as not doing so did not give any gains in our benchmarks.

Crates

Crate	crates.io	Purpose
`vdf-rs`	yes	VDF trait and Pietrzak / Wesolowski implementations
`vdf-classgroup`	yes	Class group arithmetic (GMP-backed)
`vdf-cli`	no	Command-line tool
`vdf-competition`	no	Competition helper binary

Requirements

Rust 1.85+
GNU Multiple Precision Library (GMP)

On Debian/Ubuntu:

sudo apt-get install -y libgmp-dev

On macOS (Homebrew):

brew install gmp

Usage

git clone https://github.com/jose-compu/vdf-rs.git
cd vdf-rs
cargo install --path vdf-cli

Command-line interface

vdf-cli aa 100

For Pietrzak proofs, pass -tpietrzak. Run vdf-cli --help for details.

Library

Add to Cargo.toml:

vdf-rs = "0.2"

use vdf_rs::{PietrzakVDFParams, VDFParams, VDF};

fn main() {
    let vdf = PietrzakVDFParams(2048).new();
    let proof = vdf.solve(b"\xaa", 100).unwrap();
    assert!(vdf.verify(b"\xaa", 100, &proof).is_ok());
}

Development

cargo fmt --all
cargo clippy --workspace --all-targets -- -D warnings
cargo test --workspace
./bench.sh aadf

License

Licensed under the Apache License, Version 2.0. See LICENSE and NOTICE.

vdf-rs 0.2.0