elliptic

Documentation

Overview

Package elliptic implements several standard elliptic curves over prime fields.

Index

• func GenerateKey(curve Curve, rand io.Reader) (priv []byte, x, y *big.Int, err error)
• func Marshal(curve Curve, x, y *big.Int) []byte
• func Unmarshal(curve Curve, data []byte) (x, y *big.Int)
• type Curve
  • func P224() Curve
  • func P256() Curve
  • func P384() Curve
  • func P521() Curve
• type CurveParams
  • func (curve *CurveParams) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int)
  • func (curve *CurveParams) Double(x1, y1 *big.Int) (*big.Int, *big.Int)
  • func (curve *CurveParams) IsOnCurve(x, y *big.Int) bool
  • func (curve *CurveParams) Params() *CurveParams
  • func (curve *CurveParams) ScalarBaseMult(k []byte) (*big.Int, *big.Int)
  • func (curve *CurveParams) ScalarMult(Bx, By *big.Int, k []byte) (*big.Int, *big.Int)

Functions

func GenerateKey

func GenerateKey(curve Curve, rand io.Reader) (priv []byte, x, y *big.Int, err error)

GenerateKey returns a public/private key pair. The private key is generated using the given reader, which must return random data.

func Marshal

func Marshal(curve Curve, x, y *big.Int) []byte

Marshal converts a point into the uncompressed form specified in section 4.3.6 of ANSI X9.62.

func Unmarshal

func Unmarshal(curve Curve, data []byte) (x, y *big.Int)

Unmarshal converts a point, serialized by Marshal, into an x, y pair. It is an error if the point is not in uncompressed form or is not on the curve. On error, x = nil.

Types

type Curve

type Curve interface {
	Params() *CurveParams

	IsOnCurve(x, y *big.Int) bool

	Add(x1, y1, x2, y2 *big.Int) (x, y *big.Int)

	Double(x1, y1 *big.Int) (x, y *big.Int)

	ScalarMult(x1, y1 *big.Int, k []byte) (x, y *big.Int)

	ScalarBaseMult(k []byte) (x, y *big.Int)
}

A Curve represents a short-form Weierstrass curve with a=-3. See https://www.hyperelliptic.org/EFD/g1p/auto-shortw.html

func P224

func P224() Curve

P224 returns a Curve which implements P-224 (see FIPS 186-3, section D.2.2).

The cryptographic operations are implemented using constant-time algorithms.

func P256

func P256() Curve

P256 returns a Curve which implements P-256 (see FIPS 186-3, section D.2.3)

The cryptographic operations are implemented using constant-time algorithms.

func P384

func P384() Curve

P384 returns a Curve which implements P-384 (see FIPS 186-3, section D.2.4)

The cryptographic operations do not use constant-time algorithms.

func P521

func P521() Curve

P521 returns a Curve which implements P-521 (see FIPS 186-3, section D.2.5)

The cryptographic operations do not use constant-time algorithms.

type CurveParams

type CurveParams struct {
	P       *big.Int
	N       *big.Int
	B       *big.Int
	Gx, Gy  *big.Int
	BitSize int
	Name    string
}

CurveParams contains the parameters of an elliptic curve and also provides a generic, non-constant time implementation of Curve.

func (*CurveParams) Add

func (curve *CurveParams) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int)

func (*CurveParams) Double

func (curve *CurveParams) Double(x1, y1 *big.Int) (*big.Int, *big.Int)

func (*CurveParams) IsOnCurve

func (curve *CurveParams) IsOnCurve(x, y *big.Int) bool

func (*CurveParams) Params

func (curve *CurveParams) Params() *CurveParams

func (*CurveParams) ScalarBaseMult

func (curve *CurveParams) ScalarBaseMult(k []byte) (*big.Int, *big.Int)

func (*CurveParams) ScalarMult

func (curve *CurveParams) ScalarMult(Bx, By *big.Int, k []byte) (*big.Int, *big.Int)