// Again, the chance of this happening is cryptographically negligible.
	if s.IsZero() == 1 {
		return nil, errors.New("ecdsa: internal error: s is zero")
	}

	return encodeSignature(r.Bytes(c.N), s.Bytes(c.N))
}

func encodeSignature(r, s []byte) ([]byte, error) {
	var b cryptobyte.Builder
	b.AddASN1(asn1.SEQUENCE, func(b *cryptobyte.Builder) {
		addASN1IntBytes(b, r)
		addASN1IntBytes(b, s)
	})