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Documentation

Index

• func NAF(k []byte) ([]byte, []byte)
• type KoblitzCurve
  • func S256() *KoblitzCurve
  • func (curve *KoblitzCurve) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int)
  • func (curve *KoblitzCurve) Double(x1, y1 *big.Int) (*big.Int, *big.Int)
  • func (curve *KoblitzCurve) IsOnCurve(x, y *big.Int) bool
  • func (curve *KoblitzCurve) Params() *elliptic.CurveParams
  • func (curve *KoblitzCurve) QPlus1Div4() *big.Int
  • func (curve *KoblitzCurve) ScalarBaseMult(k []byte) (*big.Int, *big.Int)
  • func (curve *KoblitzCurve) ScalarMult(Bx, By *big.Int, k []byte) (*big.Int, *big.Int)

Functions

func NAF

func NAF(k []byte) ([]byte, []byte)

NAF takes a positive integer k and returns the Non-Adjacent Form (NAF) as two byte slices. The first is where 1s will be. The second is where -1s will be. NAF is convenient in that on average, only 1/3rd of its values are non-zero. This is algorithm 3.30 from [GECC].

Essentially, this makes it possible to minimize the number of operations since the resulting ints returned will be at least 50% 0s.

Types

type KoblitzCurve

type KoblitzCurve struct {
	*elliptic.CurveParams

	H int // cofactor of the curve.
	// contains filtered or unexported fields
}

KoblitzCurve supports a koblitz curve implementation that fits the ECC Curve interface from crypto/elliptic.

func S256

func S256() *KoblitzCurve

S256 returns a Curve which implements secp256k1.

func (*KoblitzCurve) Add

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

Add returns the sum of (x1,y1) and (x2,y2). Part of the elliptic.Curve interface.

func (*KoblitzCurve) Double

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

Double returns 2*(x1,y1). Part of the elliptic.Curve interface.

func (*KoblitzCurve) IsOnCurve

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

IsOnCurve returns boolean if the point (x,y) is on the curve. Part of the elliptic.Curve interface. This function differs from the crypto/elliptic algorithm since a = 0 not -3.

func (*KoblitzCurve) Params

func (curve *KoblitzCurve) Params() *elliptic.CurveParams

Params returns the parameters for the curve.

func (*KoblitzCurve) QPlus1Div4

func (curve *KoblitzCurve) QPlus1Div4() *big.Int

QPlus1Div4 returns the Q+1/4 constant for the curve for use in calculating square roots via exponention.

func (*KoblitzCurve) ScalarBaseMult

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

ScalarBaseMult returns k*G where G is the base point of the group and k is a big endian integer. Part of the elliptic.Curve interface.

func (*KoblitzCurve) ScalarMult

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

ScalarMult returns k*(Bx, By) where k is a big endian integer. Part of the elliptic.Curve interface.