Beispiel #1
0
// Open reveals which member private key made the given signature. The return
// value will match the result of calling Tag on the member private key in
// question.
func (priv *PrivateKey) Open(sig []byte) ([]byte, bool) {
	if len(sig) != 12*32 {
		return nil, false
	}

	t1, ok := new(bn256.G1).Unmarshal(sig[:2*32])
	if !ok {
		return nil, false
	}
	t2, ok := new(bn256.G1).Unmarshal(sig[2*32 : 4*32])
	if !ok {
		return nil, false
	}
	t3, ok := new(bn256.G1).Unmarshal(sig[4*32 : 6*32])
	if !ok {
		return nil, false
	}

	a := new(bn256.G1).ScalarMult(t1, priv.xi1)
	b := new(bn256.G1).ScalarMult(t2, priv.xi2)
	a.Add(a, b)
	a.Neg(a)
	a.Add(t3, a)

	return a.Marshal(), true
}
Beispiel #2
0
// Update alters mem to create a member private key for an updated Group. (Note
// that the Group of mem must also be updated.) This functions returns false if
// mem is the member private key that has been revoked.
func (mem *MemberKey) Update(r *Revocation) bool {
	if mem.x.Cmp(r.x) == 0 {
		return false
	}

	d := new(big.Int).Sub(mem.x, r.x)
	d.Mod(d, bn256.Order)
	d.ModInverse(d, bn256.Order)

	newA := new(bn256.G1).ScalarMult(r.a, d)
	t := new(bn256.G1).ScalarMult(mem.a, d)
	t.Neg(t)
	newA.Add(newA, t)

	mem.a = newA
	return true
}