elliptic

package
Version: v0.0.0-...-ae31599 Latest Latest
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Published: Oct 8, 2015 License: BSD-3-Clause Imports: 3 Imported by: 0

Documentation

Overview

Package elliptic implements several standard elliptic curves over prime fields.

Index

Constants

This section is empty.

Variables

This section is empty.

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 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 on the curve. On error, x = nil.

Types

type Curve

type Curve interface {
	// Params returns the parameters for the curve.
	Params() *CurveParams
	// IsOnCurve reports whether the given (x,y) lies on the curve.
	IsOnCurve(x, y *big.Int) bool
	// Add returns the sum of (x1,y1) and (x2,y2)
	Add(x1, y1, x2, y2 *big.Int) (x, y *big.Int)
	// Double returns 2*(x,y)
	Double(x1, y1 *big.Int) (x, y *big.Int)
	// ScalarMult returns k*(Bx,By) where k is a number in big-endian form.
	ScalarMult(x1, y1 *big.Int, k []byte) (x, y *big.Int)
	// ScalarBaseMult returns k*G, where G is the base point of the group
	// and k is an integer in big-endian form.
	ScalarBaseMult(k []byte) (x, y *big.Int)
}

A Curve represents a short-form Weierstrass curve with a=-3. See http://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)

func P256

func P256() Curve

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

func P384

func P384() Curve

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

func P521

func P521() Curve

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

type CurveParams

type CurveParams struct {
	P       *big.Int // the order of the underlying field
	N       *big.Int // the order of the base point
	B       *big.Int // the constant of the curve equation
	Gx, Gy  *big.Int // (x,y) of the base point
	BitSize int      // the size of the underlying field
	Name    string   // the canonical name of the curve
}

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)

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