vrf-rs

vrf-rs is an open source implementation of Verifiable Random Functions (VRFs) written in Rust.

DISCLAIMER: This is experimental software. Be careful!

Elliptic Curve VRF

This module uses the OpenSSL library to offer Elliptic Curve Verifiable Random Function (VRF) functionality.

It follows the algorithms described in:

• VRF-draft-04
• RFC6979

Currently the supported cipher suites are:

• P256_SHA256_TAI: the aforementioned algorithms with SHA256 and the secp256r1 (aka NIST P-256) curve.
• K163_SHA256_TAI: the aforementioned algorithms with SHA256 and the sect163k1 (aka NIST K-163) curve.
• SECP256K1_SHA256_TAI: the aforementioned algorithms with SHA256 and the secp256k1 curve.

Example

Create and verify a VRF proof by using the cipher suite SECP256K1_SHA256_TAI:

```rust use vrf::openssl::{CipherSuite, ECVRF}; use vrf::VRF;

fn main() { // Initialization of VRF context by providing a curve let mut vrf = ECVRF::fromsuite(CipherSuite::SECP256K1SHA256TAI).unwrap(); // Inputs: Secret Key, Public Key (derived) & Message let secretkey = hex::decode("c9afa9d845ba75166b5c215767b1d6934e50c3db36e89b127b8a622b120f6721").unwrap(); let publickey = vrf.derivepublickey(&secretkey).unwrap(); let message: &[u8] = b"sample";

// VRF proof and hash output
let pi = vrf.prove(&secret_key, &message).unwrap();
let hash = vrf.proof_to_hash(&pi).unwrap();

// VRF proof verification (returns VRF hash output)
let beta = vrf.verify(&public_key, &pi, &message);

} ```

A complete example can be found in examples/basic.rs

Adding unsupported cipher suites

This library defines a VRF trait which can be extended in order to use different curves and algorithms.

```rust pub trait VRF { type Error;

fn prove(&mut self, x: SecretKey, alpha: &[u8]) -> Result<Vec<u8>, Self::Error>;

fn verify(&mut self, y: PublicKey, pi: &[u8], alpha: &[u8]) -> Result<Vec<u8>, Self::Error>;

} ```

License

vrf-rs is published under the GNU General Public License v3.0.