Function Verify

sign/bls/bls.go:39–50

Verify checks the given BLS signature S on the message m using the public key X by verifying that the equality e(H(m), X) == e(H(m), x*B2) == e(x*H(m), B2) == e(S, B2) holds where e is the pairing operation and B2 is the base point from curve G2.

(suite suites.Suite, X kyber.Point, msg, sig []byte)

// e(x*H(m), B2) == e(S, B2) holds where e is the pairing operation and B2 is
// the base point from curve G2.
func Verify(suite suites.Suite, X kyber.Point, msg, sig []byte) error {
	HM := hashToPoint(suite, msg)
	s := suite.G1().Point()
	if err := s.UnmarshalBinary(sig); err != nil {
		return err
	}
	s.Neg(s)
	if !suite.PairingCheck([]kyber.Point{s, HM}, []kyber.Point{suite.G2().Point().Base(), X}) {
		return errors.New("bls: invalid signature")
	}
	return nil
}

// hashToPoint hashes a message to a point on curve G1. XXX: This should be replaced
// eventually by a proper hash-to-point mapping like Elligator.