internal byte[] SignHash(byte[] hash, byte[] randomK)
#endif
{
if (hash == null)
{
throw new ArgumentNullException();
}
if (hash.Length == 0)
{
throw new ArgumentException();
}
if (_params.D == null && _params.Q == null)
{
_params.CreateNewPrivateKey();
}
if (_params.D == null)
{
throw new CryptographicException();
}
Number r, s, k;
IFiniteField field = _params.Domain.FieldN;
int keyBytes = (int)((_params.Domain.Bits >> 3) + ((_params.Domain.Bits & 7) == 0 ? 0U : 1U));
byte[] raw = new byte[keyBytes << 1];
Number e = HashToNumber(hash);
do
{
do
{
// Step.1
#if TEST
k = randomK == null
? k = Number.CreateRandomElement(_params.Domain.N)
: new Number(randomK, false);
#else
k = Number.CreateRandomElement(_params.Domain.N);
#endif
// Step.2
ECPoint tmp = _params.Domain.G.Multiply(k).Export();
// Step.3
r = tmp.X % _params.Domain.N;
if (!r.IsZero())
{
r.CopyToBigEndian(raw, 0, keyBytes);
break;
}
} while (true);
// Step.4
k = field.Invert(field.ToElement(k));
// Step.6
r = field.ToElement(r);
e = field.ToElement(e);
s = field.Multiply(k, field.Add(e, field.Multiply(r, field.ToElement(_params.D))));
if (!s.IsZero())
{
s = field.ToNormal(s);
s.CopyToBigEndian(raw, raw.Length >> 1, keyBytes);
break;
}
} while (true);
return(raw);
}
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);
}
