Golang abstract.Group類代碼示例

// InitNull does the same thing as Init PLUS initialize every points / coef to the Null
// Identity Element so we can use it like a "temp" / "aggregate" variable to add with others poly
func (pub *PubPoly) InitNull(g abstract.Group, k int, b abstract.Point) *PubPoly {
	pub.Init(g, k, b)
	for i, _ := range pub.p {
		pub.p[i] = g.Point().Null()
	}
	return pub
}

func EncryptPoint(g abstract.Group, msgPt abstract.Point, pk abstract.Point) (abstract.Point, abstract.Point) {
	k := g.Scalar().Pick(random.Stream)
	c1 := g.Point().Mul(nil, k)
	c2 := g.Point().Mul(pk, k)
	c2 = c2.Add(c2, msgPt)
	return c1, c2
}

func testHiding(g abstract.Group, k int) {
	rand := random.Stream

	// Test conversion from random strings to points and back
	p := g.Point()
	p2 := g.Point()
	l := p.(abstract.Hiding).HideLen()
	buf := make([]byte, l)
	for i := 0; i < k; i++ {
		rand.XORKeyStream(buf, buf)
		//println("R "+hex.EncodeToString(buf))
		p.(abstract.Hiding).HideDecode(buf)
		//println("P "+p.String())
		b2 := p.(abstract.Hiding).HideEncode(rand)
		if b2 == nil {
			panic("HideEncode failed")
		}
		//println("R'"+hex.EncodeToString(b2))
		p2.(abstract.Hiding).HideDecode(b2)
		//println("P'"+p2.String())
		if !p.Equal(p2) {
			panic("HideDecode produced wrong point")
		}
		//println("")
	}
}

func NewGroupBench(g abstract.Group) *GroupBench {
	var gb GroupBench
	gb.g = g
	gb.x = g.Secret().Pick(random.Stream)
	gb.y = g.Secret().Pick(random.Stream)
	gb.xe, _ = gb.x.MarshalBinary()
	gb.X, _ = g.Point().Pick(nil, random.Stream)
	gb.Y, _ = g.Point().Pick(nil, random.Stream)
	gb.Xe, _ = gb.X.MarshalBinary()
	return &gb
}

// Create a fresh sharing polynomial in the Secret space of a given group.
// Shares the provided Secret s, or picks a random one if s == nil.
func (p *PriPoly) Pick(g abstract.Group, k int, s0 abstract.Secret,
	rand cipher.Stream) *PriPoly {
	p.g = g
	s := make([]abstract.Secret, k)
	if s0 == nil { // Choose secret to share if none provided
		s0 = g.Secret().Pick(rand)
	}
	s[0] = s0
	for i := 1; i < k; i++ {
		s[i] = g.Secret().Pick(rand)
	}
	p.s = s
	return p
}

func testScalarClone(g abstract.Group, rand cipher.Stream) {
	N := 1000
	one := g.Scalar().One()
	for i := 0; i < N; i++ {
		s1 := g.Scalar().Pick(rand)
		s2 := s1.Clone()
		if !s1.Equal(s2) {
			panic("Clone didn't create a scalar s2 with same value as s1's.")
		}
		if !s1.Equal(one) {
			s1.Mul(s1, s1)
			if s1.Equal(s2) {
				panic("Modifying s1 shouldn't modify s2")
			}
		}
	}
}

func testPointClone(g abstract.Group, rand cipher.Stream) {
	N := 1000
	null := g.Point().Null()
	for i := 0; i < N; i++ {
		P1, _ := g.Point().Pick(nil, rand)
		P2 := P1.Clone()
		if !P1.Equal(P2) {
			panic("Clone didn't create a point with same " +
				"coordinates as the original point.")
		}
		if !P1.Equal(null) {
			P1.Add(P1, P1)
			if P1.Equal(P2) {
				panic("Modifying P1 shouldn't modify P2")
			}
		}
	}
}

func testEmbed(g abstract.Group, rand cipher.Stream, points *[]abstract.Point,
	s string) {
	//println("embedding: ",s)
	b := []byte(s)

	p, rem := g.Point().Pick(b, rand)
	//println("embedded, remainder",len(rem),"/",len(b),":",string(rem))
	x, err := p.Data()
	if err != nil {
		panic("Point extraction failed: " + err.Error())
	}
	//println("extracted data: ",string(x))

	if !bytes.Equal(append(x, rem...), b) {
		panic("Point embedding corrupted the data")
	}

	*points = append(*points, p)
}

// Simple helper to compute G^{ab-cd} for Theta vector computation.
func thenc(grp abstract.Group, G abstract.Point,
	a, b, c, d abstract.Scalar) abstract.Point {

	var ab, cd abstract.Scalar
	if a != nil {
		ab = grp.Scalar().Mul(a, b)
	} else {
		ab = grp.Scalar().Zero()
	}
	if c != nil {
		if d != nil {
			cd = grp.Scalar().Mul(c, d)
		} else {
			cd = c
		}
	} else {
		cd = grp.Scalar().Zero()
	}
	return grp.Point().Mul(G, ab.Sub(ab, cd))
}

func Shuffle(pi []int, group abstract.Group, g, h abstract.Point, X, Y []abstract.Point,
	rand cipher.Stream) (XX, YY []abstract.Point, P proof.Prover) {

	k := len(X)
	if k != len(Y) {
		panic("X,Y vectors have inconsistent length")
	}

	ps := shuffle.PairShuffle{}
	ps.Init(group, k)

	// Pick a fresh ElGamal blinding factor for each pair
	beta := make([]abstract.Scalar, k)
	for i := 0; i < k; i++ {
		beta[i] = group.Scalar().Pick(rand)
	}

	// Create the output pair vectors
	Xbar := make([]abstract.Point, k)
	Ybar := make([]abstract.Point, k)
	for i := 0; i < k; i++ {
		Xbar[i] = group.Point().Mul(g, beta[pi[i]])
		Xbar[i].Add(Xbar[i], X[pi[i]])
		Ybar[i] = group.Point().Mul(h, beta[pi[i]])
		Ybar[i].Add(Ybar[i], Y[pi[i]])
	}

	prover := func(ctx proof.ProverContext) error {
		return ps.Prove(pi, g, h, beta, X, Y, rand, ctx)
	}
	return Xbar, Ybar, prover
}

func EncryptKey(g abstract.Group, msgPt abstract.Point, pks []abstract.Point) (abstract.Point, abstract.Point) {
	k := g.Scalar().Pick(random.Stream)
	c1 := g.Point().Mul(nil, k)
	var c2 abstract.Point = nil
	for _, pk := range pks {
		if c2 == nil {
			c2 = g.Point().Mul(pk, k)
		} else {
			c2 = c2.Add(c2, g.Point().Mul(pk, k))
		}
	}
	c2 = c2.Add(c2, msgPt)
	return c1, c2
}

func Encrypt(g abstract.Group, msg []byte, pks []abstract.Point) ([]abstract.Point, []abstract.Point) {
	c1s := []abstract.Point{}
	c2s := []abstract.Point{}
	var msgPt abstract.Point
	remainder := msg
	for len(remainder) != 0 {
		msgPt, remainder = g.Point().Pick(remainder, random.Stream)
		k := g.Scalar().Pick(random.Stream)
		c1 := g.Point().Mul(nil, k)
		var c2 abstract.Point = nil
		for _, pk := range pks {
			if c2 == nil {
				c2 = g.Point().Mul(pk, k)
			} else {
				c2 = c2.Add(c2, g.Point().Mul(pk, k))
			}
		}
		c2 = c2.Add(c2, msgPt)
		c1s = append(c1s, c1)
		c2s = append(c2s, c2)
	}
	return c1s, c2s
}

func testPointSet(g abstract.Group, rand cipher.Stream) {
	N := 1000
	null := g.Point().Null()
	for i := 0; i < N; i++ {
		P1, _ := g.Point().Pick(nil, rand)
		P2 := g.Point()
		P2.Set(P1)
		if !P1.Equal(P2) {
			panic("Set() set to a different point.")
		}
		if !P1.Equal(null) {
			P1.Add(P1, P1)
			if P1.Equal(P2) {
				panic("Modifying P1 shouldn't modify P2")
			}
		}
	}
}

func Decrypt(g abstract.Group, c1 abstract.Point, c2 abstract.Point, sk abstract.Scalar) abstract.Point {
	return g.Point().Sub(c2, g.Point().Mul(c1, sk))
}

	"github.com/dedis/crypto/abstract"
	"github.com/dedis/crypto/edwards"
	"github.com/dedis/crypto/random"
)

/* This file is a testing suite for sharing.go. It provides multiple test cases
 * for ensuring that encryption schemes built upon this package such as Shamir
 * secret sharing are safe and secure.
 *
 * The tests can also serve as references for how to work with this library.
 */

/* Global Variables */

var group abstract.Group = new(edwards.ExtendedCurve).Init(
	edwards.Param25519(), false)
var altGroup abstract.Group = new(edwards.ProjectiveCurve).Init(
	edwards.ParamE382(), false)
var k int = 10
var n int = 20
var secret = group.Scalar().Pick(random.Stream)
var point = group.Point().Mul(group.Point().Base(), secret)
var altSecret = altGroup.Scalar().Pick(random.Stream)
var altPoint = altGroup.Point().Mul(altGroup.Point().Base(), altSecret)

/* Setup Functions
 *
 * These functions provide greater modularity by consolidating commonly used
 * setup tasks.
 *
 * Not every function uses these methods, since they may have unique set-up