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Diffstat (limited to 'vendor/elliptic-curve/src/ops.rs')
-rw-r--r-- | vendor/elliptic-curve/src/ops.rs | 79 |
1 files changed, 79 insertions, 0 deletions
diff --git a/vendor/elliptic-curve/src/ops.rs b/vendor/elliptic-curve/src/ops.rs new file mode 100644 index 0000000..b7e9e3d --- /dev/null +++ b/vendor/elliptic-curve/src/ops.rs @@ -0,0 +1,79 @@ +//! Traits for arithmetic operations on elliptic curve field elements. + +pub use core::ops::{Add, AddAssign, Mul, Neg, Shr, ShrAssign, Sub, SubAssign}; + +use crypto_bigint::Integer; +use group::Group; + +/// Perform an inversion on a field element (i.e. base field element or scalar) +pub trait Invert { + /// Field element type + type Output; + + /// Invert a field element. + fn invert(&self) -> Self::Output; + + /// Invert a field element in variable time. + /// + /// ⚠️ WARNING! + /// + /// This method should not be used with secret values, as its variable-time + /// operation can potentially leak secrets through sidechannels. + fn invert_vartime(&self) -> Self::Output { + // Fall back on constant-time implementation by default. + self.invert() + } +} + +/// Linear combination. +/// +/// This trait enables crates to provide an optimized implementation of +/// linear combinations (e.g. Shamir's Trick), or otherwise provides a default +/// non-optimized implementation. +// TODO(tarcieri): replace this with a trait from the `group` crate? (see zkcrypto/group#25) +pub trait LinearCombination: Group { + /// Calculates `x * k + y * l`. + fn lincomb(x: &Self, k: &Self::Scalar, y: &Self, l: &Self::Scalar) -> Self { + (*x * k) + (*y * l) + } +} + +/// Multiplication by the generator. +/// +/// May use optimizations (e.g. precomputed tables) when available. +// TODO(tarcieri): replace this with `Group::mul_by_generator``? (see zkcrypto/group#44) +pub trait MulByGenerator: Group { + /// Multiply by the generator of the prime-order subgroup. + #[must_use] + fn mul_by_generator(scalar: &Self::Scalar) -> Self { + Self::generator() * scalar + } +} + +/// Modular reduction. +pub trait Reduce<Uint: Integer>: Sized { + /// Bytes used as input to [`Reduce::reduce_bytes`]. + type Bytes: AsRef<[u8]>; + + /// Perform a modular reduction, returning a field element. + fn reduce(n: Uint) -> Self; + + /// Interpret the given bytes as an integer and perform a modular reduction. + fn reduce_bytes(bytes: &Self::Bytes) -> Self; +} + +/// Modular reduction to a non-zero output. +/// +/// This trait is primarily intended for use by curve implementations such +/// as the `k256` and `p256` crates. +/// +/// End users should use the [`Reduce`] impl on +/// [`NonZeroScalar`][`crate::NonZeroScalar`] instead. +pub trait ReduceNonZero<Uint: Integer>: Reduce<Uint> + Sized { + /// Perform a modular reduction, returning a field element. + fn reduce_nonzero(n: Uint) -> Self; + + /// Interpret the given bytes as an integer and perform a modular reduction + /// to a non-zero output. + fn reduce_nonzero_bytes(bytes: &Self::Bytes) -> Self; +} |