reddsa/src/lib.rs

// -*- mode: rust; -*-
//
// This file is part of reddsa.
// Copyright (c) 2019-2021 Zcash Foundation
// See LICENSE for licensing information.
//
// Authors:
// - Deirdre Connolly <deirdre@zfnd.org>
// - Henry de Valence <hdevalence@hdevalence.ca>

#![deny(missing_docs)]
#![doc = include_str!("../README.md")]

pub mod batch;
mod constants;
mod error;
pub mod frost;
mod hash;
mod messages;
mod scalar_mul;
pub(crate) mod signature;
mod signing_key;
mod verification_key;

/// An element of the JubJub scalar field used for randomization of public and secret keys.
pub type Randomizer = jubjub::Scalar;

use hash::HStar;

pub use error::Error;
pub use signature::Signature;
pub use signing_key::SigningKey;
pub use verification_key::{VerificationKey, VerificationKeyBytes};

/// Abstracts over different RedJubJub parameter choices, [`Binding`]
/// and [`SpendAuth`].
///
/// As described [at the end of §5.4.6][concretereddsa] of the Zcash
/// protocol specification, the generator used in RedJubjub is left as
/// an unspecified parameter, chosen differently for each of
/// `BindingSig` and `SpendAuthSig`.
///
/// To handle this, we encode the parameter choice as a genuine type
/// parameter.
///
/// [concretereddsa]: https://zips.z.cash/protocol/protocol.pdf#concretereddsa
pub trait SigType: private::Sealed {}

/// A type variable corresponding to Zcash's `BindingSig`.
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub enum Binding {}
impl SigType for Binding {}

/// A type variable corresponding to Zcash's `SpendAuthSig`.
#[derive(Copy, Clone, PartialEq, Eq, Debug)]
pub enum SpendAuth {}
impl SigType for SpendAuth {}

pub(crate) mod private {
    use super::*;
    pub trait Sealed: Copy + Clone + Eq + PartialEq + std::fmt::Debug {
        fn basepoint() -> jubjub::ExtendedPoint;
    }
    impl Sealed for Binding {
        fn basepoint() -> jubjub::ExtendedPoint {
            jubjub::AffinePoint::from_bytes(constants::BINDINGSIG_BASEPOINT_BYTES)
                .unwrap()
                .into()
        }
    }
    impl Sealed for SpendAuth {
        fn basepoint() -> jubjub::ExtendedPoint {
            jubjub::AffinePoint::from_bytes(constants::SPENDAUTHSIG_BASEPOINT_BYTES)
                .unwrap()
                .into()
        }
    }
}