protected override ECPoint DecompressPoint(int yTilde, BigInteger X1)
{
ECFieldElement xp = FromBigInteger(X1), yp;
if (xp.IsZero)
{
yp = m_b.Sqrt();
}
else
{
ECFieldElement beta = xp.Square().Invert().Multiply(B).Add(A).Add(xp);
ECFieldElement z = SolveQuadradicEquation(beta);
if (z == null)
{
throw new ArithmeticException("Invalid point compression");
}
if (z.TestBitZero() != (yTilde == 1))
{
z = z.AddOne();
}
switch (this.CoordinateSystem)
{
case COORD_LAMBDA_AFFINE:
case COORD_LAMBDA_PROJECTIVE:
{
yp = z.Add(xp);
break;
}
default:
{
yp = z.Multiply(xp);
break;
}
}
}
return(new F2mPoint(this, xp, yp, true));
}
protected override ECPoint DecompressPoint(int yTilde, BigInteger X1)
{
//IL_009b: Unknown result type (might be due to invalid IL or missing references)
ECFieldElement eCFieldElement = FromBigInteger(X1);
ECFieldElement eCFieldElement2 = null;
if (eCFieldElement.IsZero)
{
eCFieldElement2 = B.Sqrt();
}
else
{
ECFieldElement beta = eCFieldElement.Square().Invert().Multiply(B)
.Add(A)
.Add(eCFieldElement);
ECFieldElement eCFieldElement3 = SolveQuadradicEquation(beta);
if (eCFieldElement3 != null)
{
if (eCFieldElement3.TestBitZero() != (yTilde == 1))
{
eCFieldElement3 = eCFieldElement3.AddOne();
}
switch (CoordinateSystem)
{
case 5:
case 6:
eCFieldElement2 = eCFieldElement3.Add(eCFieldElement);
break;
default:
eCFieldElement2 = eCFieldElement3.Multiply(eCFieldElement);
break;
}
}
}
if (eCFieldElement2 == null)
{
throw new ArgumentException("Invalid point compression");
}
return(CreateRawPoint(eCFieldElement, eCFieldElement2, withCompression: true));
}
protected override ECPoint DecompressPoint(int yTilde, BigInteger X1)
{
ECFieldElement x = FromBigInteger(X1);
ECFieldElement rhs = x.Square().Add(A).Multiply(x).Add(B);
ECFieldElement y = rhs.Sqrt();
/*
* If y is not a square, then we haven't got a point on the curve
*/
if (y == null)
{
throw new ArgumentException("Invalid point compression");
}
if (y.TestBitZero() != (yTilde == 1))
{
// Use the other root
y = y.Negate();
}
return(CreateRawPoint(x, y, true));
}
protected override ECPoint DecompressPoint(int yTilde, BigInteger X1)
{
ECFieldElement eCFieldElement = this.FromBigInteger(X1);
ECFieldElement eCFieldElement2 = null;
if (eCFieldElement.IsZero)
{
eCFieldElement2 = this.m_b.Sqrt();
}
else
{
ECFieldElement beta = eCFieldElement.Square().Invert().Multiply(this.B).Add(this.A).Add(eCFieldElement);
ECFieldElement eCFieldElement3 = this.SolveQuadradicEquation(beta);
if (eCFieldElement3 != null)
{
if (eCFieldElement3.TestBitZero() != (yTilde == 1))
{
eCFieldElement3 = eCFieldElement3.AddOne();
}
switch (this.CoordinateSystem)
{
case 5:
case 6:
eCFieldElement2 = eCFieldElement3.Add(eCFieldElement);
break;
default:
eCFieldElement2 = eCFieldElement3.Multiply(eCFieldElement);
break;
}
}
}
if (eCFieldElement2 == null)
{
throw new ArgumentException("Invalid point compression");
}
return(this.CreateRawPoint(eCFieldElement, eCFieldElement2, true));
}
protected override ECPoint DecompressPoint(int yTilde, BigInteger X1)
{
ECFieldElement x = FromBigInteger(X1);
ECFieldElement alpha = x.Square().Add(m_a).Multiply(x).Add(m_b);
ECFieldElement beta = alpha.Sqrt();
//
// if we can't find a sqrt we haven't got a point on the
// curve - run!
//
if (beta == null)
{
throw new ArithmeticException("Invalid point compression");
}
if (beta.TestBitZero() != (yTilde == 1))
{
// Use the other root
beta = beta.Negate();
}
return(new FpPoint(this, x, beta, true));
}
protected override ECPoint DecompressPoint(int yTilde, BigInteger X1)
{
ECFieldElement b = this.FromBigInteger(X1);
ECFieldElement y = null;
if (b.IsZero)
{
y = this.B.Sqrt();
}
else
{
ECFieldElement beta = b.Square().Invert().Multiply(this.B).Add(this.A).Add(b);
ECFieldElement element4 = this.SolveQuadradicEquation(beta);
if (element4 != null)
{
if (element4.TestBitZero() != (yTilde == 1))
{
element4 = element4.AddOne();
}
switch (this.CoordinateSystem)
{
case 5:
case 6:
y = element4.Add(b);
goto Label_00A9;
}
y = element4.Multiply(b);
}
}
Label_00A9:
if (y == null)
{
throw new ArgumentException("Invalid point compression");
}
return(this.CreateRawPoint(b, y, true));
}
