// Given a witness and secret nonces, respond to a challenge proving the equation holds w.r.t the witness
internal static ScalarVector Respond(ScalarVector witness, ScalarVector secretNonces, Scalar challenge)
{
// blinding terms are required in order to protect the witness (unless the
// challenge is 0), so only respond if that is the case
foreach (var secretNonce in secretNonces)
{
CryptoGuard.NotZero(nameof(secretNonce), secretNonce);
}
// Taking the discrete logarithms of both sides of the verification
// equation with respect to G results in a formula for the response s
// given k, e and x:
// s = k + ex
return(secretNonces + challenge * witness);
}
