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using System;
using Org.BouncyCastle.Math.Raw;
namespace Org.BouncyCastle.Math.EC.Custom.Sec
{
internal class SecT233K1Point
: AbstractF2mPoint
{
internal SecT233K1Point(ECCurve curve, ECFieldElement x, ECFieldElement y)
: base(curve, x, y)
{
}
internal SecT233K1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, ECFieldElement[] zs)
: base(curve, x, y, zs)
{
}
protected override ECPoint Detach()
{
return new SecT233K1Point(null, this.AffineXCoord, this.AffineYCoord);
}
public override ECFieldElement YCoord
{
get
{
ECFieldElement X = RawXCoord, L = RawYCoord;
if (this.IsInfinity || X.IsZero)
return L;
// Y is actually Lambda (X + Y/X) here; convert to affine value on the fly
ECFieldElement Y = L.Add(X).Multiply(X);
ECFieldElement Z = RawZCoords[0];
if (!Z.IsOne)
{
Y = Y.Divide(Z);
}
return Y;
}
}
protected internal override bool CompressionYTilde
{
get
{
ECFieldElement X = this.RawXCoord;
if (X.IsZero)
return false;
ECFieldElement Y = this.RawYCoord;
// Y is actually Lambda (X + Y/X) here
return Y.TestBitZero() != X.TestBitZero();
}
}
public override ECPoint Add(ECPoint b)
{
if (this.IsInfinity)
return b;
if (b.IsInfinity)
return this;
ECCurve curve = this.Curve;
SecT233FieldElement X1 = (SecT233FieldElement)this.RawXCoord;
SecT233FieldElement X2 = (SecT233FieldElement)b.RawXCoord;
if (X1.IsZero)
{
if (X2.IsZero)
return curve.Infinity;
return b.Add(this);
}
SecT233FieldElement L1 = (SecT233FieldElement)this.RawYCoord, Z1 = (SecT233FieldElement)this.RawZCoords[0];
SecT233FieldElement L2 = (SecT233FieldElement)b.RawYCoord, Z2 = (SecT233FieldElement)b.RawZCoords[0];
ulong[] tt0 = Nat256.CreateExt64();
ulong[] t1 = Nat256.Create64();
ulong[] t2 = Nat256.Create64();
ulong[] t3 = Nat256.Create64();
bool Z1IsOne = Z1.IsOne;
if (Z1IsOne)
{
Nat256.Copy64(X2.x, t1); // U2
Nat256.Copy64(L2.x, t2); // S2
}
else
{
SecT233Field.Multiply(X2.x, Z1.x, t1); // U2
SecT233Field.Multiply(L2.x, Z1.x, t2); // S2
}
bool Z2IsOne = Z2.IsOne;
if (Z2IsOne)
{
Nat256.Copy64(X1.x, t3); // U1
Nat256.Copy64(L1.x, tt0); // S1
}
else
{
SecT233Field.Multiply(X1.x, Z2.x, t3); // U1
SecT233Field.Multiply(L1.x, Z2.x, tt0); // S1
}
SecT233Field.AddTo(tt0, t2); // A
SecT233Field.Add(t3, t1, tt0); // B
if (Nat256.IsZero64(tt0))
{
if (Nat256.IsZero64(t2))
return Twice();
return curve.Infinity;
}
if (X2.IsZero)
{
// TODO This can probably be optimized quite a bit
ECPoint p = this.Normalize();
X1 = (SecT233FieldElement)p.XCoord;
ECFieldElement Y1 = p.YCoord;
ECFieldElement Y2 = L2;
ECFieldElement L = Y1.Add(Y2).Divide(X1);
ECFieldElement X3 = L.Square().Add(L).Add(X1);
if (X3.IsZero)
return new SecT233K1Point(curve, X3, curve.B);
ECFieldElement Y3 = L.Multiply(X1.Add(X3)).Add(X3).Add(Y1);
ECFieldElement L3 = Y3.Divide(X3).Add(X3);
ECFieldElement Z3 = curve.FromBigInteger(BigInteger.One);
return new SecT233K1Point(curve, X3, L3, new ECFieldElement[]{ Z3 });
}
SecT233Field.Square(tt0, tt0);
SecT233Field.Multiply(t3, t2, t3); // AU1
SecT233Field.Multiply(t1, t2, t1); // AU2
ulong[] _X3 = t3;
SecT233Field.Multiply(_X3, t1, _X3);
if (Nat256.IsZero64(_X3))
return new SecT233K1Point(curve, new SecT233FieldElement(_X3), curve.B);
ulong[] _Z3 = t2;
SecT233Field.Multiply(_Z3, tt0, _Z3); // ABZ2
if (!Z2IsOne)
{
SecT233Field.Multiply(_Z3, Z2.x, _Z3);
}
ulong[] _L3 = t1;
SecT233Field.AddTo(tt0, _L3);
SecT233Field.SquareExt(_L3, tt0);
SecT233Field.Add(L1.x, Z1.x, _L3);
SecT233Field.MultiplyAddToExt(_Z3, _L3, tt0);
SecT233Field.Reduce(tt0, _L3);
if (!Z1IsOne)
{
SecT233Field.Multiply(_Z3, Z1.x, _Z3);
}
return new SecT233K1Point(curve, new SecT233FieldElement(_X3), new SecT233FieldElement(_L3),
new ECFieldElement[]{ new SecT233FieldElement(_Z3) });
}
public override ECPoint Twice()
{
if (this.IsInfinity)
{
return this;
}
ECCurve curve = this.Curve;
ECFieldElement X1 = this.RawXCoord;
if (X1.IsZero)
{
// A point with X == 0 is its own additive inverse
return curve.Infinity;
}
ECFieldElement L1 = this.RawYCoord, Z1 = this.RawZCoords[0];
bool Z1IsOne = Z1.IsOne;
ECFieldElement Z1Sq = Z1IsOne ? Z1 : Z1.Square();
ECFieldElement T;
if (Z1IsOne)
{
T = L1.Square().Add(L1);
}
else
{
T = L1.Add(Z1).Multiply(L1);
}
if (T.IsZero)
{
return new SecT233K1Point(curve, T, curve.B);
}
ECFieldElement X3 = T.Square();
ECFieldElement Z3 = Z1IsOne ? T : T.Multiply(Z1Sq);
ECFieldElement t1 = L1.Add(X1).Square();
ECFieldElement t2 = Z1IsOne ? Z1 : Z1Sq.Square();
ECFieldElement L3 = t1.Add(T).Add(Z1Sq).Multiply(t1).Add(t2).Add(X3).Add(Z3);
return new SecT233K1Point(curve, X3, L3, new ECFieldElement[] { Z3 });
}
public override ECPoint TwicePlus(ECPoint b)
{
if (this.IsInfinity)
return b;
if (b.IsInfinity)
return Twice();
ECCurve curve = this.Curve;
ECFieldElement X1 = this.RawXCoord;
if (X1.IsZero)
{
// A point with X == 0 is its own additive inverse
return b;
}
// NOTE: TwicePlus() only optimized for lambda-affine argument
ECFieldElement X2 = b.RawXCoord, Z2 = b.RawZCoords[0];
if (X2.IsZero || !Z2.IsOne)
{
return Twice().Add(b);
}
ECFieldElement L1 = this.RawYCoord, Z1 = this.RawZCoords[0];
ECFieldElement L2 = b.RawYCoord;
ECFieldElement X1Sq = X1.Square();
ECFieldElement L1Sq = L1.Square();
ECFieldElement Z1Sq = Z1.Square();
ECFieldElement L1Z1 = L1.Multiply(Z1);
ECFieldElement T = L1Sq.Add(L1Z1);
ECFieldElement L2plus1 = L2.AddOne();
ECFieldElement A = L2plus1.Multiply(Z1Sq).Add(L1Sq).MultiplyPlusProduct(T, X1Sq, Z1Sq);
ECFieldElement X2Z1Sq = X2.Multiply(Z1Sq);
ECFieldElement B = X2Z1Sq.Add(T).Square();
if (B.IsZero)
{
if (A.IsZero)
{
return b.Twice();
}
return curve.Infinity;
}
if (A.IsZero)
{
return new SecT233K1Point(curve, A, curve.B);
}
ECFieldElement X3 = A.Square().Multiply(X2Z1Sq);
ECFieldElement Z3 = A.Multiply(B).Multiply(Z1Sq);
ECFieldElement L3 = A.Add(B).Square().MultiplyPlusProduct(T, L2plus1, Z3);
return new SecT233K1Point(curve, X3, L3, new ECFieldElement[] { Z3 });
}
public override ECPoint Negate()
{
if (this.IsInfinity)
return this;
ECFieldElement X = this.RawXCoord;
if (X.IsZero)
return this;
// L is actually Lambda (X + Y/X) here
ECFieldElement L = this.RawYCoord, Z = this.RawZCoords[0];
return new SecT233K1Point(Curve, X, L.Add(Z), new ECFieldElement[] { Z });
}
}
}
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