bitcurves

Documentation

Overview

Package bitelliptic implements several Koblitz elliptic curves over prime fields.

Package bitelliptic implements several Koblitz elliptic curves over prime fields.

Index

• Variables
• type BitCurve
  • func S160() *BitCurve
  • func S192() *BitCurve
  • func S224() *BitCurve
  • func S256() *BitCurve
  • func (bitCurve *BitCurve) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int)
  • func (bitCurve *BitCurve) Double(x1, y1 *big.Int) (*big.Int, *big.Int)
  • func (bitCurve *BitCurve) GenerateKey(rand io.Reader) (priv []byte, x, y *big.Int, err error)
  • func (bitCurve *BitCurve) IsOnCurve(x, y *big.Int) bool
  • func (bitCurve *BitCurve) Marshal(x, y *big.Int) []byte
  • func (bitCurve *BitCurve) Params() (cp *elliptic.CurveParams)
  • func (bitCurve *BitCurve) ScalarBaseMult(k []byte) (*big.Int, *big.Int)
  • func (bitCurve *BitCurve) ScalarMult(Bx, By *big.Int, k []byte) (*big.Int, *big.Int)
  • func (bitCurve *BitCurve) Unmarshal(data []byte) (x, y *big.Int)

Variables

var (
	OIDNamedCurveSecp160k1 = asn1.ObjectIdentifier{1, 3, 132, 0, 9}
	OIDNamedCurveSecp192k1 = asn1.ObjectIdentifier{1, 3, 132, 0, 31}
	OIDNamedCurveSecp224k1 = asn1.ObjectIdentifier{1, 3, 132, 0, 32}
	OIDNamedCurveSecp256k1 = asn1.ObjectIdentifier{1, 3, 132, 0, 10}
)

Types

type BitCurve

type BitCurve struct {
	Name    string
	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 BitCurve equation
	Gx, Gy  *big.Int // (x,y) of the base point
	BitSize int      // the size of the underlying field
}

A BitCurve represents a Koblitz Curve with a=0. See http://www.hyperelliptic.org/EFD/g1p/auto-shortw.html

func S160

func S160() *BitCurve

S160 returns a BitCurve which implements secp160k1 (see SEC 2 section 2.4.1)

func S192

func S192() *BitCurve

S192 returns a BitCurve which implements secp192k1 (see SEC 2 section 2.5.1)

func S224

func S224() *BitCurve

S224 returns a BitCurve which implements secp224k1 (see SEC 2 section 2.6.1)

func S256

func S256() *BitCurve

S256 returns a BitCurve which implements bitcurves (see SEC 2 section 2.7.1)

func (*BitCurve) Add

func (bitCurve *BitCurve) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int)

Add returns the sum of (x1,y1) and (x2,y2)

func (*BitCurve) Double

func (bitCurve *BitCurve) Double(x1, y1 *big.Int) (*big.Int, *big.Int)

Double returns 2*(x,y)

func (*BitCurve) GenerateKey

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

TODO: double check if it is okay GenerateKey returns a public/private key pair. The private key is generated using the given reader, which must return random data.

func (*BitCurve) IsOnCurve

func (bitCurve *BitCurve) IsOnCurve(x, y *big.Int) bool

IsOnCurve returns true if the given (x,y) lies on the BitCurve.

func (*BitCurve) Marshal

func (bitCurve *BitCurve) Marshal(x, y *big.Int) []byte

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

func (*BitCurve) Params

func (bitCurve *BitCurve) Params() (cp *elliptic.CurveParams)

Params returns the parameters of the given BitCurve (see BitCurve struct)

func (*BitCurve) ScalarBaseMult

func (bitCurve *BitCurve) ScalarBaseMult(k []byte) (*big.Int, *big.Int)

ScalarBaseMult returns k*G, where G is the base point of the group and k is an integer in big-endian form.

func (*BitCurve) ScalarMult

func (bitCurve *BitCurve) ScalarMult(Bx, By *big.Int, k []byte) (*big.Int, *big.Int)

ScalarMult returns k*(Bx,By) where k is a number in big-endian form.

func (*BitCurve) Unmarshal

func (bitCurve *BitCurve) Unmarshal(data []byte) (x, y *big.Int)

Unmarshal converts a point, serialised by Marshal, into an x, y pair. On error, x = nil.