Esempio n. 1
0
// ScalarEncodeTo provides a generic implementation of Scalar.EncodeTo
// based on Scalar.Encode.
func ScalarMarshalTo(s abstract.Scalar, w io.Writer) (int, error) {
	buf, err := s.MarshalBinary()
	if err != nil {
		return 0, err
	}
	return w.Write(buf)
}
Esempio n. 2
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// 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))
}
Esempio n. 3
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// ScalarDecodeFrom provides a generic implementation of Scalar.DecodeFrom,
// based on Scalar.Decode, or Scalar.Pick if r is a Cipher or cipher.Stream.
// The returned byte-count is valid only when decoding from a normal Reader,
// not when picking from a pseudorandom source.
func ScalarUnmarshalFrom(s abstract.Scalar, r io.Reader) (int, error) {
	if strm, ok := r.(cipher.Stream); ok {
		s.Pick(strm)
		return -1, nil // no byte-count when picking randomly
	}
	buf := make([]byte, s.MarshalSize())
	n, err := io.ReadFull(r, buf)
	if err != nil {
		return n, err
	}
	return n, s.UnmarshalBinary(buf)
}
Esempio n. 4
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// Simple helper to verify Theta elements,
// by checking whether A^a*B^-b = T.
// P,Q,s are simply "scratch" abstract.Point/Scalars reused for efficiency.
func thver(A, B, T, P, Q abstract.Point, a, b, s abstract.Scalar) bool {
	P.Mul(A, a)
	Q.Mul(B, s.Neg(b))
	P.Add(P, Q)
	return P.Equal(T)
}
Esempio n. 5
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// ScalarHex encodes a scalar to hexadecimal
func ScalarHex(suite abstract.Suite, scalar abstract.Scalar) (string, error) {
	sbuf, err := scalar.MarshalBinary()
	return hex.EncodeToString(sbuf), err
}