twistededwards

Documentation

Overview

Package twistededwards provides bn254's twisted edwards "companion curve" defined on fr.

Index

• type CurveParams
  • func GetEdwardsCurve() CurveParams
• type PointAffine
  • func NewPointAffine(x, y fr.Element) PointAffine
  • func (p *PointAffine) Add(p1, p2 *PointAffine) *PointAffine
  • func (p *PointAffine) Bytes() [sizePointCompressed]byte
  • func (p *PointAffine) Double(p1 *PointAffine) *PointAffine
  • func (p *PointAffine) Equal(p1 *PointAffine) bool
  • func (p *PointAffine) FromProj(p1 *PointProj) *PointAffine
  • func (p *PointAffine) IsOnCurve() bool
  • func (p *PointAffine) Marshal() []byte
  • func (p *PointAffine) Neg(p1 *PointAffine) *PointAffine
  • func (p *PointAffine) ScalarMul(p1 *PointAffine, scalar *big.Int) *PointAffine
  • func (p *PointAffine) Set(p1 *PointAffine) *PointAffine
  • func (p *PointAffine) SetBytes(buf []byte) (int, error)
  • func (p *PointAffine) Unmarshal(b []byte) error
• type PointProj
  • func (p *PointProj) Add(p1, p2 *PointProj) *PointProj
  • func (p *PointProj) Double(p1 *PointProj) *PointProj
  • func (p *PointProj) Equal(p1 *PointProj) bool
  • func (p *PointProj) FromAffine(p1 *PointAffine) *PointProj
  • func (p *PointProj) Neg(p1 *PointProj) *PointProj
  • func (p *PointProj) Set(p1 *PointProj) *PointProj

Types

type CurveParams

type CurveParams struct {
	A, D     fr.Element // in Montgomery form
	Cofactor fr.Element // not in Montgomery form
	Order    big.Int
	Base     PointAffine
}

CurveParams curve parameters: ax^2 + y^2 = 1 + d*x^2*y^2

func GetEdwardsCurve

func GetEdwardsCurve() CurveParams

GetEdwardsCurve returns the twisted Edwards curve on BN254's Fr

type PointAffine

type PointAffine struct {
	X, Y fr.Element
}

PointAffine point on a twisted Edwards curve

func NewPointAffine

func NewPointAffine(x, y fr.Element) PointAffine

NewPointAffine creates a new instance of PointAffine

func (*PointAffine) Add

func (p *PointAffine) Add(p1, p2 *PointAffine) *PointAffine

Add adds two points (x,y), (u,v) on a twisted Edwards curve with parameters a, d modifies p

func (*PointAffine) Bytes

func (p *PointAffine) Bytes() [sizePointCompressed]byte

Bytes returns the compressed point as a byte array Follows https://tools.ietf.org/html/rfc8032#section-3.1, as the twisted Edwards implementation is primarily used for eddsa.

func (*PointAffine) Double

func (p *PointAffine) Double(p1 *PointAffine) *PointAffine

Double doubles point (x,y) on a twisted Edwards curve with parameters a, d modifies p

func (*PointAffine) Equal

func (p *PointAffine) Equal(p1 *PointAffine) bool

Equal returns true if p=p1 false otherwise

func (*PointAffine) FromProj

func (p *PointAffine) FromProj(p1 *PointProj) *PointAffine

FromProj sets p in affine from p in projective

func (*PointAffine) IsOnCurve

func (p *PointAffine) IsOnCurve() bool

IsOnCurve checks if a point is on the twisted Edwards curve

func (*PointAffine) Marshal

func (p *PointAffine) Marshal() []byte

Marshal converts p to a byte slice

func (*PointAffine) Neg

func (p *PointAffine) Neg(p1 *PointAffine) *PointAffine

Neg sets p to -p1 and returns it

func (*PointAffine) ScalarMul

func (p *PointAffine) ScalarMul(p1 *PointAffine, scalar *big.Int) *PointAffine

ScalarMul scalar multiplication of a point p1 points on the twisted Edwards curve c parameters of the twisted Edwards curve scal scalar NOT in Montgomery form modifies p func (p *PointAffine) ScalarMul(p1 *PointAffine, scalar fr.Element) *PointAffine {

func (*PointAffine) Set

func (p *PointAffine) Set(p1 *PointAffine) *PointAffine

Set sets p to p1 and return it

func (*PointAffine) SetBytes

func (p *PointAffine) SetBytes(buf []byte) (int, error)

SetBytes sets p from buf len(buf) >= sizePointCompressed buf contains the Y coordinate masked with a parity bit to recompute the X coordinate from the curve equation. See Bytes() and https://tools.ietf.org/html/rfc8032#section-3.1 Returns the number of read bytes and an error if the buffer is too short.

func (*PointAffine) Unmarshal

func (p *PointAffine) Unmarshal(b []byte) error

Unmarshal alias to SetBytes()

type PointProj

type PointProj struct {
	X, Y, Z fr.Element
}

PointProj point in projective coordinates

func (*PointProj) Add

func (p *PointProj) Add(p1, p2 *PointProj) *PointProj

Add adds points in projective coordinates cf https://hyperelliptic.org/EFD/g1p/auto-twisted-projective.html

func (*PointProj) Double

func (p *PointProj) Double(p1 *PointProj) *PointProj

Double adds points in projective coordinates cf https://hyperelliptic.org/EFD/g1p/auto-twisted-projective.html

func (*PointProj) Equal

func (p *PointProj) Equal(p1 *PointProj) bool

Equal returns true if p=p1 false otherwise If one point is on the affine chart Z=0 it returns false

func (*PointProj) FromAffine

func (p *PointProj) FromAffine(p1 *PointAffine) *PointProj

FromAffine sets p in projective from p in affine

func (*PointProj) Neg

func (p *PointProj) Neg(p1 *PointProj) *PointProj

Neg negates point (x,y) on a twisted Edwards curve with parameters a, d modifies p

func (*PointProj) Set

func (p *PointProj) Set(p1 *PointProj) *PointProj

Set sets p to p1 and return it