111 lines
4.0 KiB
Rust
111 lines
4.0 KiB
Rust
//! A library for working with pairing-friendly curves.
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// `clippy` is a code linting tool for improving code quality by catching
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// common mistakes or strange code patterns. If the `cargo-clippy` feature
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// is provided, all compiler warnings are prohibited.
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#![cfg_attr(feature = "cargo-clippy", deny(warnings))]
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#![cfg_attr(feature = "cargo-clippy", allow(clippy::inline_always))]
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#![cfg_attr(feature = "cargo-clippy", allow(clippy::too_many_arguments))]
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#![cfg_attr(feature = "cargo-clippy", allow(clippy::unreadable_literal))]
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#![cfg_attr(feature = "cargo-clippy", allow(clippy::many_single_char_names))]
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#![cfg_attr(feature = "cargo-clippy", allow(clippy::new_without_default))]
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#![cfg_attr(feature = "cargo-clippy", allow(clippy::write_literal))]
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// Catch documentation errors caused by code changes.
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#![deny(intra_doc_link_resolution_failure)]
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// Force public structures to implement Debug
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#![deny(missing_debug_implementations)]
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#[cfg(test)]
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pub mod tests;
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pub mod bls12_381;
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use ff::{Field, PrimeField, ScalarEngine, SqrtField};
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use group::{CurveAffine, CurveOps, CurveOpsOwned, CurveProjective};
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use subtle::CtOption;
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/// An "engine" is a collection of types (fields, elliptic curve groups, etc.)
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/// with well-defined relationships. In particular, the G1/G2 curve groups are
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/// of prime order `r`, and are equipped with a bilinear pairing function.
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pub trait Engine: ScalarEngine {
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/// The projective representation of an element in G1.
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type G1: CurveProjective<Engine = Self, Base = Self::Fq, Scalar = Self::Fr, Affine = Self::G1Affine>
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+ From<Self::G1Affine>
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+ CurveOps<Self::G1Affine>
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+ CurveOpsOwned<Self::G1Affine>;
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/// The affine representation of an element in G1.
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type G1Affine: PairingCurveAffine<
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Engine = Self,
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Base = Self::Fq,
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Scalar = Self::Fr,
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Projective = Self::G1,
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Pair = Self::G2Affine,
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PairingResult = Self::Fqk,
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> + From<Self::G1>;
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/// The projective representation of an element in G2.
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type G2: CurveProjective<Engine = Self, Base = Self::Fqe, Scalar = Self::Fr, Affine = Self::G2Affine>
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+ From<Self::G2Affine>
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+ CurveOps<Self::G2Affine>
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+ CurveOpsOwned<Self::G2Affine>;
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/// The affine representation of an element in G2.
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type G2Affine: PairingCurveAffine<
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Engine = Self,
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Base = Self::Fqe,
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Scalar = Self::Fr,
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Projective = Self::G2,
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Pair = Self::G1Affine,
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PairingResult = Self::Fqk,
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> + From<Self::G2>;
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/// The base field that hosts G1.
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type Fq: PrimeField + SqrtField;
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/// The extension field that hosts G2.
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type Fqe: SqrtField;
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/// The extension field that hosts the target group of the pairing.
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type Fqk: Field;
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/// Perform a miller loop with some number of (G1, G2) pairs.
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fn miller_loop<'a, I>(i: I) -> Self::Fqk
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where
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I: IntoIterator<
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Item = &'a (
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&'a <Self::G1Affine as PairingCurveAffine>::Prepared,
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&'a <Self::G2Affine as PairingCurveAffine>::Prepared,
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),
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>;
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/// Perform final exponentiation of the result of a miller loop.
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fn final_exponentiation(_: &Self::Fqk) -> CtOption<Self::Fqk>;
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/// Performs a complete pairing operation `(p, q)`.
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fn pairing<G1, G2>(p: G1, q: G2) -> Self::Fqk
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where
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G1: Into<Self::G1Affine>,
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G2: Into<Self::G2Affine>,
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{
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Self::final_exponentiation(&Self::miller_loop(
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[(&(p.into().prepare()), &(q.into().prepare()))].iter(),
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))
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.unwrap()
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}
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}
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/// Affine representation of an elliptic curve point that can be used
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/// to perform pairings.
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pub trait PairingCurveAffine: CurveAffine {
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type Prepared: Clone + Send + Sync + 'static;
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type Pair: PairingCurveAffine<Pair = Self>;
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type PairingResult: Field;
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/// Prepares this element for pairing purposes.
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fn prepare(&self) -> Self::Prepared;
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/// Perform a pairing
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fn pairing_with(&self, other: &Self::Pair) -> Self::PairingResult;
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}
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