Struct EdwardsPointExpression

pub struct EdwardsPointExpression<F: Field, C: EdwardsCurve<F>> { /* private fields */ }

An embedded Edwards curve point defined over the same base field as the field used in the constraint system, with affine coordinates as expressions.

Implementations

impl<F: Field, C: EdwardsCurve<F>> EdwardsPointExpression<F, C>

pub fn compressed(&self) -> &Expression<F>

Returns the Y coordinate of an EdwardsPointExpression

pub fn add( builder: &mut GadgetBuilder<F>, point_1: &EdwardsPointExpression<F, C>, point_2: &EdwardsPointExpression<F, C>, ) -> EdwardsPointExpression<F, C>

Assumes that the EdwardsPointExpressions are known to be contained on the curve (and omits a membership check), so the non-deterministic inversion method is valid.

pub fn double( builder: &mut GadgetBuilder<F>, point: &EdwardsPointExpression<F, C>, ) -> EdwardsPointExpression<F, C>

Naive implementation of the doubling algorithm for twisted Edwards curves.

Assuming that EdwardsPointExpressions are on the curve, so the non-deterministic division method is acceptable, as the denominator is non-zero.

Note that this algorithm requires the point to be of odd order, which, in the case of prime-order subgroups of Edwards curves, is satisfied.

pub fn scalar_mult( builder: &mut GadgetBuilder<F>, point: &EdwardsPointExpression<F, C>, scalar: &Expression<F>, ) -> EdwardsPointExpression<F, C>

Multiplies an EdwardsPointExpression by a scalar using a naive approach consisting of multiplication by doubling.

pub fn identity() -> EdwardsPointExpression<F, C>

Identity element for twisted Edwards Curve

pub fn from_elements( x: Element<F>, y: Element<F>, ) -> EdwardsPointExpression<F, C>

Takes two elements as coordinates, checks that they’re on the curve without adding constraints, and then returns an EdwardsPointExpression

pub fn from_edwards_point(p: EdwardsPoint<F, C>) -> EdwardsPointExpression<F, C>

Converts an EdwardsPoint into an EdwardsPointExpression. Assumes that the coordinates of the EdwardsPoint have already been verified on the curve

pub fn from_expressions( builder: &mut GadgetBuilder<F>, x: Expression<F>, y: Expression<F>, ) -> EdwardsPointExpression<F, C>

Takes two expressions as coordinates, adds constraints verifying that the coordinates are contained on the specified curve, and then returns an EdwardsPointExpression

pub fn from_expressions_unsafe( x: Expression<F>, y: Expression<F>, ) -> EdwardsPointExpression<F, C>

Takes two expressions as coordinates, does not perform a check or add constraints to check that the coordinates are on the specified curve, and then returns an EdwardsPointExpression

pub fn evaluate(&self, values: &WireValues<F>) -> EdwardsPoint<F, C>

Evaluates the EdwardsPointExpression by evaluating the expression in each coordinate

Trait Implementations

impl<F: Field, C: EdwardsCurve<F>> Clone for EdwardsPointExpression<F, C>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.