bn256

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Published: May 6, 2022 License: GPL-3.0, BSD-3-Clause Imports: 4 Imported by: 0

Documentation

Index

Examples

Constants

This section is empty.

Variables

View Source
var Order = bigFromBase10("21888242871839275222246405745257275088548364400416034343698204186575808495617")

Order is the number of elements in both G₁ and G₂: 36u⁴+36u³+18u²+6u+1.

View Source
var P = bigFromBase10("21888242871839275222246405745257275088696311157297823662689037894645226208583")

p is a prime over which we form a basic field: 36u⁴+36u³+24u²+6u+1.

Functions

func PairingCheck

func PairingCheck(a []*G1, b []*G2) bool

PairingCheck calculates the Optimal Ate pairing for a set of points.

Types

type G1

type G1 struct {
	// contains filtered or unexported fields
}

BUG(agl): this implementation is not constant time. G1 is an abstract cyclic group. The zero value is suitable for use as the output of an operation, but cannot be used as an input.

func RandomG1

func RandomG1(r io.Reader) (*big.Int, *G1, error)

RandomG1 returns x and g₁ˣ where x is a random, non-zero number read from r.

func (*G1) Add

func (e *G1) Add(a, b *G1) *G1

Add sets e to a+b and then returns e. BUG(agl): this function is not complete: a==b fails.

func (*G1) CurvePoints

func (e *G1) CurvePoints() (*big.Int, *big.Int, *big.Int, *big.Int)

CurvePoints returns p's curve points in big integer

func (*G1) Marshal

func (e *G1) Marshal() []byte

Marshal converts n to a byte slice.

func (*G1) Neg

func (e *G1) Neg(a *G1) *G1

Neg sets e to -a and then returns e.

func (*G1) ScalarBaseMult

func (e *G1) ScalarBaseMult(k *big.Int) *G1

ScalarBaseMult sets e to g*k where g is the generator of the group and then returns e.

func (*G1) ScalarMult

func (e *G1) ScalarMult(a *G1, k *big.Int) *G1

ScalarMult sets e to a*k and then returns e.

func (*G1) String

func (e *G1) String() string

func (*G1) Unmarshal

func (e *G1) Unmarshal(m []byte) ([]byte, error)

Unmarshal sets e to the result of converting the output of Marshal back into a group element and then returns e.

type G2

type G2 struct {
	// contains filtered or unexported fields
}

G2 is an abstract cyclic group. The zero value is suitable for use as the output of an operation, but cannot be used as an input.

func RandomG2

func RandomG2(r io.Reader) (*big.Int, *G2, error)

RandomG1 returns x and g₂ˣ where x is a random, non-zero number read from r.

func (*G2) Add

func (e *G2) Add(a, b *G2) *G2

Add sets e to a+b and then returns e. BUG(agl): this function is not complete: a==b fails.

func (*G2) CurvePoints

func (e *G2) CurvePoints() (*gfP2, *gfP2, *gfP2, *gfP2)

CurvePoints returns the curve points of p which includes the real and imaginary parts of the curve point.

func (*G2) Marshal

func (n *G2) Marshal() []byte

Marshal converts n into a byte slice.

func (*G2) ScalarBaseMult

func (e *G2) ScalarBaseMult(k *big.Int) *G2

ScalarBaseMult sets e to g*k where g is the generator of the group and then returns out.

func (*G2) ScalarMult

func (e *G2) ScalarMult(a *G2, k *big.Int) *G2

ScalarMult sets e to a*k and then returns e.

func (*G2) String

func (e *G2) String() string

func (*G2) Unmarshal

func (e *G2) Unmarshal(m []byte) ([]byte, error)

Unmarshal sets e to the result of converting the output of Marshal back into a group element and then returns e.

type GT

type GT struct {
	// contains filtered or unexported fields
}

GT is an abstract cyclic group. The zero value is suitable for use as the output of an operation, but cannot be used as an input.

func Pair

func Pair(g1 *G1, g2 *G2) *GT

Pair calculates an Optimal Ate pairing.

Example
// This implements the tripartite Diffie-Hellman algorithm from "A One
// Round Protocol for Tripartite Diffie-Hellman", A. Joux.
// http://www.springerlink.com/content/cddc57yyva0hburb/fulltext.pdf

// Each of three parties, a, b and c, generate a private value.
a, _ := rand.Int(rand.Reader, Order)
b, _ := rand.Int(rand.Reader, Order)
c, _ := rand.Int(rand.Reader, Order)

// Then each party calculates g₁ and g₂ times their private value.
pa := new(G1).ScalarBaseMult(a)
qa := new(G2).ScalarBaseMult(a)

pb := new(G1).ScalarBaseMult(b)
qb := new(G2).ScalarBaseMult(b)

pc := new(G1).ScalarBaseMult(c)
qc := new(G2).ScalarBaseMult(c)

// Now each party exchanges its public values with the other two and
// all parties can calculate the shared key.
k1 := Pair(pb, qc)
k1.ScalarMult(k1, a)

k2 := Pair(pc, qa)
k2.ScalarMult(k2, b)

k3 := Pair(pa, qb)
k3.ScalarMult(k3, c)

// k1, k2 and k3 will all be equal.
Output:

func (*GT) Add

func (e *GT) Add(a, b *GT) *GT

Add sets e to a+b and then returns e.

func (*GT) Marshal

func (n *GT) Marshal() []byte

Marshal converts n into a byte slice.

func (*GT) Neg

func (e *GT) Neg(a *GT) *GT

Neg sets e to -a and then returns e.

func (*GT) ScalarMult

func (e *GT) ScalarMult(a *GT, k *big.Int) *GT

ScalarMult sets e to a*k and then returns e.

func (*GT) String

func (g *GT) String() string

func (*GT) Unmarshal

func (e *GT) Unmarshal(m []byte) (*GT, bool)

Unmarshal sets e to the result of converting the output of Marshal back into a group element and then returns e.

Notes

Bugs

  • this implementation is not constant time. G1 is an abstract cyclic group. The zero value is suitable for use as the output of an operation, but cannot be used as an input.

  • this function is not complete: a==b fails.

  • this function is not complete: a==b fails.

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