| public static GetLucas ( sbyte mu, int k, bool doV ) : BigInteger[] | ||
| mu | sbyte | |
| k | int | |
| doV | bool | |
| return | BigInteger[] | |
public static BigInteger[] GetSi(AbstractF2mCurve curve)
{
if (!curve.IsKoblitz)
{
throw new ArgumentException("si is defined for Koblitz curves only");
}
int fieldSize = curve.FieldSize;
int intValue = curve.A.ToBigInteger().IntValue;
sbyte mu = Tnaf.GetMu(intValue);
int shiftsForCofactor = Tnaf.GetShiftsForCofactor(curve.Cofactor);
int k = fieldSize + 3 - intValue;
BigInteger[] lucas = Tnaf.GetLucas(mu, k, false);
if (mu == 1)
{
lucas[0] = lucas[0].Negate();
lucas[1] = lucas[1].Negate();
}
BigInteger bigInteger = BigInteger.One.Add(lucas[1]).ShiftRight(shiftsForCofactor);
BigInteger bigInteger2 = BigInteger.One.Add(lucas[0]).ShiftRight(shiftsForCofactor).Negate();
return(new BigInteger[]
{
bigInteger,
bigInteger2
});
}
public static BigInteger GetTw(sbyte mu, int w)
{
if (w != 4)
{
BigInteger[] lucas = Tnaf.GetLucas(mu, w, false);
BigInteger m = BigInteger.Zero.SetBit(w);
BigInteger val = lucas[1].ModInverse(m);
return(BigInteger.Two.Multiply(lucas[0]).Multiply(val).Mod(m));
}
if (mu == 1)
{
return(BigInteger.ValueOf(6L));
}
return(BigInteger.ValueOf(10L));
}
public static BigInteger[] GetSi(int fieldSize, int curveA, BigInteger cofactor)
{
sbyte mu = Tnaf.GetMu(curveA);
int shiftsForCofactor = Tnaf.GetShiftsForCofactor(cofactor);
int k = fieldSize + 3 - curveA;
BigInteger[] lucas = Tnaf.GetLucas(mu, k, false);
if (mu == 1)
{
lucas[0] = lucas[0].Negate();
lucas[1] = lucas[1].Negate();
}
BigInteger bigInteger = BigInteger.One.Add(lucas[1]).ShiftRight(shiftsForCofactor);
BigInteger bigInteger2 = BigInteger.One.Add(lucas[0]).ShiftRight(shiftsForCofactor).Negate();
return(new BigInteger[]
{
bigInteger,
bigInteger2
});
}
public static ZTauElement PartModReduction(BigInteger k, int m, sbyte a, BigInteger[] s, sbyte mu, sbyte c)
{
BigInteger bigInteger;
if (mu == 1)
{
bigInteger = s[0].Add(s[1]);
}
else
{
bigInteger = s[0].Subtract(s[1]);
}
BigInteger[] lucas = Tnaf.GetLucas(mu, m, true);
BigInteger vm = lucas[1];
SimpleBigDecimal lambda = Tnaf.ApproximateDivisionByN(k, s[0], vm, a, m, (int)c);
SimpleBigDecimal lambda2 = Tnaf.ApproximateDivisionByN(k, s[1], vm, a, m, (int)c);
ZTauElement zTauElement = Tnaf.Round(lambda, lambda2, mu);
BigInteger u = k.Subtract(bigInteger.Multiply(zTauElement.u)).Subtract(BigInteger.ValueOf(2L).Multiply(s[1]).Multiply(zTauElement.v));
BigInteger v = s[1].Multiply(zTauElement.u).Subtract(s[0].Multiply(zTauElement.v));
return(new ZTauElement(u, v));
}
