#cryptography #vrf #ecvrf

vrf-mod

An extensible rust library for building VRF functionality with support for Elliptical Curve VRFs (secp256k1, secp256r1 curves)

2 releases

Uses new Rust 2021

new 0.1.2 Sep 18, 2022
0.1.1 Sep 18, 2022
0.1.0 Sep 18, 2022

#379 in Cryptography

50 downloads per month

MIT license

66KB
1K SLoC

vrf-mod

vrf-mod is an open source implementation of Verifiable Random Functions (VRFs) and Elliptical Curve VRFs written in Rust. This library follows algorithms described in:

Disclaimer: Experimental

VRF

This module uses the OpenSSL library for big number cryptographic arithmetic.

Supported cipher suites include:

  • PKI_MGF_MGF1_SHA1: mask generation algorithm utilizing SHA1.
  • PKI_MGF_MGF1_SHA256: mask generation algorithm utilizing SHA256.
use vrf_mod::vrf::{VRFCipherSuite, VRF};
use vrf_mod::VRF as VRF_trait;
use openssl::rsa::Rsa;

fn main() {
    // Initialization of VRF context
    let mut vrf = VRF::from_suite(VRFCipherSuite::PKI_MGF_MGF1_SHA256).unwrap();
    // Load private key from a file
    let pkey = include_bytes!("../link_to_file/rsa.pem");
    let private_key = Rsa::private_key_from_pem(pkey).unwrap();
    // Load public key from a file
    let key = include_bytes!("../link_to_file/rsa.pem.pub");
    let public_key = Rsa::public_key_from_pem(key).unwrap();
    // Inputs: Secret Key, Public Key (derived) & Message
    let message: &[u8] = b"sample";
    
    // VRF proof and hash output
    let pi = vrf.prove(&private_key, &message).unwrap();
    let hash = vrf.proof_to_hash(&pi).unwrap();

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

Adding unsupported cipher suites

This library also defines a VRF trait which can be extended.

use openssl::{
    rsa::Rsa,
    pkey::{Public, Private}.
};

pub trait VRF {
    type Error;

    fn prove(&mut self, pkey: &Rsa<Private>, alpha_string: &[u8]) -> Result<Vec<u8>, Self::Error>;

    fn proof_to_hash(&mut self, pi_string: &[u8]) -> Result<Vec<u8>, Self::Error>;

    fn verify(&mut self, public_key: &Rsa<Public>, alpha_string: &[u8], pi_string: &[u8]) -> Result<Vec<u8>, Self::Error>;
}

Elliptical Curve VRF

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

Supported cipher suites include:

  • P256_SHA256_TAI: algorithms with SHA256 and the secp256r1 curve (aka NIST P-256).
  • SECP256K1_SHA256_TAI: algorithms with SHA256 and the secp256k1 curve.
use vrf_mod::ecvrf::{CipherSuite, ECVRF};
use vrf_mod::ECVRF as ECVRF_trait;

fn main() {
    // Initialization of VRF context by providing a curve
    let mut ecvrf = ECVRF::from_suite(CipherSuite::P256_SHA256_TAI).unwrap();
    // Private Key, Public Key (derived) & message
    let private_key = hex::decode("c9afa9d845ba75166b5c215767b1d6934e50c3db36e89b127b8a622b120f6721").unwrap();
    let public_key = ecvrf.derive_public_key(&private_key).unwrap();
    let message: &[u8] = b"sample";
    
    // ECVRF proof and hash output
    let pi = ecvrf.prove(&private_key, &message).unwrap();
    let hash = ecvrf.proof_to_hash(&pi).unwrap();

    // ECVRF proof verification (returns ECVRF hash output)
    let beta = ecvrf.verify(&public_key, &message, &pi);
}

Adding unsupported cipher suites

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

pub trait ECVRF<PrivateKey, PublicKey> {
    type Error;

    fn prove(&mut self, pkey: PrivateKey, alpha_string: &[u8]) -> Result<Vec<u8>, Self::Error>;

    fn proof_to_hash(&mut self, pi_string: &[u8]) -> Result<Vec<u8>, Self::Error>;

    fn verify(&mut self, public_key: PublicKey, alpha_string: &[u8], pi_string: &[u8]) -> Result<Vec<u8>, Self::Error>;
}

License

vrf-mod is published under the MIT license.

Dependencies

~1.6–2.3MB
~51K SLoC