From 85c484fff517135cedfe265ef893bd4b8d745300 Mon Sep 17 00:00:00 2001 From: Jack Grigg Date: Sat, 29 Jul 2023 17:32:01 +0000 Subject: [PATCH] Introduce `CurveAffine` trait This unifies the methods previously exposed by the `PrimeCurveAffine` and `CofactorCurveAffine` traits. The prime-order and cofactor traits are now all marker traits, and their affine-specific traits are automatically derived. --- CHANGELOG.md | 18 +++++++++++++++++ src/cofactor.rs | 48 ++++---------------------------------------- src/lib.rs | 52 +++++++++++++++++++++++++++++++++++++++++------- src/prime.rs | 44 ++++------------------------------------ src/tests/mod.rs | 8 ++------ 5 files changed, 73 insertions(+), 97 deletions(-) diff --git a/CHANGELOG.md b/CHANGELOG.md index aec3f6d..66eea08 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -6,6 +6,24 @@ and this library adheres to Rust's notion of [Semantic Versioning](https://semver.org/spec/v2.0.0.html). ## [Unreleased] +### Added +- `group::CurveAffine` + +### Changed +- The curve-related traits have been refactored around the new `CurveAffine` + trait: + - `group::Curve::AffineRepr` has been renamed to `Curve::Affine`. + - All of the trait methods and associated types on the following traits have + been removed (use `group::Curve::Affine` or the `group::CurveAffine` trait + instead; trait implementors must implement `group::CurveAffine` instead + using the same logic): + - `group::cofactor::CofactorCurve` + - `group::cofactor::CofactorCurveAffine` + - `group::prime::PrimeCurve` + - `group::prime::PrimeCurveAffine` + - `group::cofactor::CofactorCurveAffine` and `group::prime::PrimeCurveAffine` + now have blanket implementations for all types `C: group::CurveAffine` where + `C::Curve` implements `CofactorCurve` or `PrimeCurve` respectively. ## [0.13.0] - 2022-12-06 ### Changed diff --git a/src/cofactor.rs b/src/cofactor.rs index 84bfe0a..fae0a89 100644 --- a/src/cofactor.rs +++ b/src/cofactor.rs @@ -1,9 +1,6 @@ -use core::fmt; -use core::ops::{Mul, Neg}; -use ff::PrimeField; use subtle::{Choice, CtOption}; -use crate::{prime::PrimeGroup, Curve, Group, GroupEncoding, GroupOps, GroupOpsOwned}; +use crate::{prime::PrimeGroup, Curve, CurveAffine, Group, GroupEncoding, GroupOps, GroupOpsOwned}; /// This trait represents an element of a cryptographic group with a large prime-order /// subgroup and a comparatively-small cofactor. @@ -54,47 +51,10 @@ pub trait CofactorGroup: /// Efficient representation of an elliptic curve point guaranteed to be /// in the correct prime order subgroup. -pub trait CofactorCurve: - Curve::Affine> + CofactorGroup -{ - type Affine: CofactorCurveAffine - + Mul - + for<'r> Mul<&'r Self::Scalar, Output = Self>; -} +pub trait CofactorCurve: Curve + CofactorGroup {} /// Affine representation of an elliptic curve point guaranteed to be /// in the correct prime order subgroup. -pub trait CofactorCurveAffine: - GroupEncoding - + Copy - + Clone - + Sized - + Send - + Sync - + fmt::Debug - + PartialEq - + Eq - + 'static - + Neg - + Mul<::Scalar, Output = ::Curve> - + for<'r> Mul< - &'r ::Scalar, - Output = ::Curve, - > -{ - type Scalar: PrimeField; - type Curve: CofactorCurve; - - /// Returns the additive identity. - fn identity() -> Self; +pub trait CofactorCurveAffine: CurveAffine {} - /// Returns a fixed generator of unknown exponent. - fn generator() -> Self; - - /// Determines if this point represents the point at infinity; the - /// additive identity. - fn is_identity(&self) -> Choice; - - /// Converts this element to its curve representation. - fn to_curve(&self) -> Self::Curve; -} +impl CofactorCurveAffine for C where C::Curve: CofactorCurve {} diff --git a/src/lib.rs b/src/lib.rs index 27ed5c9..25756ed 100644 --- a/src/lib.rs +++ b/src/lib.rs @@ -92,16 +92,16 @@ pub trait Group: fn double(&self) -> Self; } -/// Efficient representation of an elliptic curve point guaranteed. -pub trait Curve: - Group + GroupOps<::AffineRepr> + GroupOpsOwned<::AffineRepr> -{ +/// Efficient representation of an elliptic curve point. +pub trait Curve: Group + GroupOps + GroupOpsOwned { /// The affine representation for this elliptic curve. - type AffineRepr; + type Affine: CurveAffine + + Mul + + for<'r> Mul<&'r Self::Scalar, Output = Self>; /// Converts a batch of projective elements into affine elements. This function will /// panic if `p.len() != q.len()`. - fn batch_normalize(p: &[Self], q: &mut [Self::AffineRepr]) { + fn batch_normalize(p: &[Self], q: &mut [Self::Affine]) { assert_eq!(p.len(), q.len()); for (p, q) in p.iter().zip(q.iter_mut()) { @@ -110,7 +110,45 @@ pub trait Curve: } /// Converts this element into its affine representation. - fn to_affine(&self) -> Self::AffineRepr; + fn to_affine(&self) -> Self::Affine; +} + +/// Affine representation of an elliptic curve point. +pub trait CurveAffine: + GroupEncoding + + Copy + + Clone + + Sized + + Send + + Sync + + fmt::Debug + + PartialEq + + Eq + + 'static + + Neg + + Mul<::Scalar, Output = Self::Curve> + + for<'r> Mul<&'r ::Scalar, Output = Self::Curve> +{ + /// The efficient representation for this elliptic curve. + type Curve: Curve; + + /// Scalars modulo the order of this group's scalar field. + /// + /// This associated type is temporary, and will be removed once downstream users have + /// migrated to using `Curve` as the primary generic bound. + type Scalar: PrimeField; + + /// Returns the additive identity. + fn identity() -> Self; + + /// Returns a fixed generator of unknown exponent. + fn generator() -> Self; + + /// Determines if this point represents the additive identity. + fn is_identity(&self) -> Choice; + + /// Converts this affine point to its efficient representation. + fn to_curve(&self) -> Self::Curve; } pub trait GroupEncoding: Sized { diff --git a/src/prime.rs b/src/prime.rs index 174888e..0964782 100644 --- a/src/prime.rs +++ b/src/prime.rs @@ -1,50 +1,14 @@ -use core::fmt; -use core::ops::{Mul, Neg}; -use ff::PrimeField; -use subtle::Choice; - -use crate::{Curve, Group, GroupEncoding}; +use crate::{Curve, CurveAffine, Group, GroupEncoding}; /// This trait represents an element of a prime-order cryptographic group. pub trait PrimeGroup: Group + GroupEncoding {} /// Efficient representation of an elliptic curve point guaranteed to be /// in the correct prime order subgroup. -pub trait PrimeCurve: Curve::Affine> + PrimeGroup { - type Affine: PrimeCurveAffine - + Mul - + for<'r> Mul<&'r Self::Scalar, Output = Self>; -} +pub trait PrimeCurve: Curve + PrimeGroup {} /// Affine representation of an elliptic curve point guaranteed to be /// in the correct prime order subgroup. -pub trait PrimeCurveAffine: GroupEncoding - + Copy - + Clone - + Sized - + Send - + Sync - + fmt::Debug - + PartialEq - + Eq - + 'static - + Neg - + Mul<::Scalar, Output = ::Curve> - + for<'r> Mul<&'r ::Scalar, Output = ::Curve> -{ - type Scalar: PrimeField; - type Curve: PrimeCurve; - - /// Returns the additive identity. - fn identity() -> Self; - - /// Returns a fixed generator of unknown exponent. - fn generator() -> Self; - - /// Determines if this point represents the point at infinity; the - /// additive identity. - fn is_identity(&self) -> Choice; +pub trait PrimeCurveAffine: CurveAffine {} - /// Converts this element to its curve representation. - fn to_curve(&self) -> Self::Curve; -} +impl PrimeCurveAffine for C where C::Curve: PrimeCurve {} diff --git a/src/tests/mod.rs b/src/tests/mod.rs index ff79a9b..89d0f15 100644 --- a/src/tests/mod.rs +++ b/src/tests/mod.rs @@ -4,11 +4,7 @@ use ff::{Field, PrimeField}; use rand::SeedableRng; use rand_xorshift::XorShiftRng; -use crate::{ - prime::{PrimeCurve, PrimeCurveAffine}, - wnaf::WnafGroup, - GroupEncoding, UncompressedEncoding, -}; +use crate::{prime::PrimeCurve, wnaf::WnafGroup, CurveAffine, GroupEncoding, UncompressedEncoding}; pub fn curve_tests() { let mut rng = XorShiftRng::from_seed([ @@ -426,7 +422,7 @@ fn random_compressed_encoding_tests() { pub fn random_uncompressed_encoding_tests() where - ::Affine: UncompressedEncoding, + G::Affine: UncompressedEncoding, { let mut rng = XorShiftRng::from_seed([ 0x59, 0x62, 0xbe, 0x5d, 0x76, 0x3d, 0x31, 0x8d, 0x17, 0xdb, 0x37, 0x32, 0x54, 0x06, 0xbc,