public bool VerifyHash(byte[] hash, byte[] sig)
{
if (sig.Length != (_params.Domain.Bits >> 2) + ((_params.Domain.Bits & 7) == 0 ? 0 : 2))
{
throw new ArgumentException();
}
if (hash.Length == 0)
{
throw new ArgumentException();
}
if (_params.Q == null && _params.D != null)
{
_params.CreatePublicKeyFromPrivateKey();
}
if (_params.Q == null)
{
throw new CryptographicException();
}
int halfLen = sig.Length >> 1;
Number r = new Number(sig, 0, halfLen, false);
Number s = new Number(sig, halfLen, halfLen, false);
Number e = HashToNumber(hash);
IFiniteField field = _params.Domain.FieldN;
if (r >= _params.Domain.N || s >= _params.Domain.N)
{
return(false);
}
// Step.1
e = field.ToElement(e);
s = field.ToElement(s);
Number r2 = field.ToElement(r);
// Step.2
Number w = field.Invert(s);
// Step.3
Number u1 = field.ToNormal(field.Multiply(e, w));
Number u2 = field.ToNormal(field.Multiply(r2, w));
// Step.4
//ECPoint X = _params.Domain.G.Multiply (u1).Add (_params.Q.Multiply (u2));
ECPoint X;
if (u1.IsZero())
{
X = _params.Domain.FieldN.GetInfinityPoint(_params.Domain.Group).Add(_params.Q.Multiply(u2));
}
else
{
X = ECPoint.MultiplyAndAdd(_params.Domain.G, u1, _params.Q, u2);
}
// Step.5
if (X.IsInifinity())
{
return(false);
}
X = X.Export();
// Step.6
Number v = X.X % _params.Domain.N;
return(r.CompareTo(v) == 0);
}