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using System;
using Org.BouncyCastle.Math.Raw;
namespace Org.BouncyCastle.Math.EC.Custom.Sec
{
internal class SecP192R1Point
: AbstractFpPoint
{
internal SecP192R1Point(ECCurve curve, ECFieldElement x, ECFieldElement y)
: base(curve, x, y)
{
}
internal SecP192R1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, ECFieldElement[] zs)
: base(curve, x, y, zs)
{
}
protected override ECPoint Detach()
{
return new SecP192R1Point(null, AffineXCoord, AffineYCoord);
}
public override ECPoint Add(ECPoint b)
{
if (this.IsInfinity)
return b;
if (b.IsInfinity)
return this;
if (this == b)
return Twice();
ECCurve curve = this.Curve;
SecP192R1FieldElement X1 = (SecP192R1FieldElement)this.RawXCoord, Y1 = (SecP192R1FieldElement)this.RawYCoord;
SecP192R1FieldElement X2 = (SecP192R1FieldElement)b.RawXCoord, Y2 = (SecP192R1FieldElement)b.RawYCoord;
SecP192R1FieldElement Z1 = (SecP192R1FieldElement)this.RawZCoords[0];
SecP192R1FieldElement Z2 = (SecP192R1FieldElement)b.RawZCoords[0];
uint c;
uint[] tt1 = Nat192.CreateExt();
uint[] t2 = Nat192.Create();
uint[] t3 = Nat192.Create();
uint[] t4 = Nat192.Create();
bool Z1IsOne = Z1.IsOne;
uint[] U2, S2;
if (Z1IsOne)
{
U2 = X2.x;
S2 = Y2.x;
}
else
{
S2 = t3;
SecP192R1Field.Square(Z1.x, S2);
U2 = t2;
SecP192R1Field.Multiply(S2, X2.x, U2);
SecP192R1Field.Multiply(S2, Z1.x, S2);
SecP192R1Field.Multiply(S2, Y2.x, S2);
}
bool Z2IsOne = Z2.IsOne;
uint[] U1, S1;
if (Z2IsOne)
{
U1 = X1.x;
S1 = Y1.x;
}
else
{
S1 = t4;
SecP192R1Field.Square(Z2.x, S1);
U1 = tt1;
SecP192R1Field.Multiply(S1, X1.x, U1);
SecP192R1Field.Multiply(S1, Z2.x, S1);
SecP192R1Field.Multiply(S1, Y1.x, S1);
}
uint[] H = Nat192.Create();
SecP192R1Field.Subtract(U1, U2, H);
uint[] R = t2;
SecP192R1Field.Subtract(S1, S2, R);
// Check if b == this or b == -this
if (Nat192.IsZero(H))
{
if (Nat192.IsZero(R))
{
// this == b, i.e. this must be doubled
return this.Twice();
}
// this == -b, i.e. the result is the point at infinity
return curve.Infinity;
}
uint[] HSquared = t3;
SecP192R1Field.Square(H, HSquared);
uint[] G = Nat192.Create();
SecP192R1Field.Multiply(HSquared, H, G);
uint[] V = t3;
SecP192R1Field.Multiply(HSquared, U1, V);
SecP192R1Field.Negate(G, G);
Nat192.Mul(S1, G, tt1);
c = Nat192.AddBothTo(V, V, G);
SecP192R1Field.Reduce32(c, G);
SecP192R1FieldElement X3 = new SecP192R1FieldElement(t4);
SecP192R1Field.Square(R, X3.x);
SecP192R1Field.Subtract(X3.x, G, X3.x);
SecP192R1FieldElement Y3 = new SecP192R1FieldElement(G);
SecP192R1Field.Subtract(V, X3.x, Y3.x);
SecP192R1Field.MultiplyAddToExt(Y3.x, R, tt1);
SecP192R1Field.Reduce(tt1, Y3.x);
SecP192R1FieldElement Z3 = new SecP192R1FieldElement(H);
if (!Z1IsOne)
{
SecP192R1Field.Multiply(Z3.x, Z1.x, Z3.x);
}
if (!Z2IsOne)
{
SecP192R1Field.Multiply(Z3.x, Z2.x, Z3.x);
}
ECFieldElement[] zs = new ECFieldElement[] { Z3 };
return new SecP192R1Point(curve, X3, Y3, zs);
}
public override ECPoint Twice()
{
if (this.IsInfinity)
return this;
ECCurve curve = this.Curve;
SecP192R1FieldElement Y1 = (SecP192R1FieldElement)this.RawYCoord;
if (Y1.IsZero)
return curve.Infinity;
SecP192R1FieldElement X1 = (SecP192R1FieldElement)this.RawXCoord, Z1 = (SecP192R1FieldElement)this.RawZCoords[0];
uint c;
uint[] t1 = Nat192.Create();
uint[] t2 = Nat192.Create();
uint[] Y1Squared = Nat192.Create();
SecP192R1Field.Square(Y1.x, Y1Squared);
uint[] T = Nat192.Create();
SecP192R1Field.Square(Y1Squared, T);
bool Z1IsOne = Z1.IsOne;
uint[] Z1Squared = Z1.x;
if (!Z1IsOne)
{
Z1Squared = t2;
SecP192R1Field.Square(Z1.x, Z1Squared);
}
SecP192R1Field.Subtract(X1.x, Z1Squared, t1);
uint[] M = t2;
SecP192R1Field.Add(X1.x, Z1Squared, M);
SecP192R1Field.Multiply(M, t1, M);
c = Nat192.AddBothTo(M, M, M);
SecP192R1Field.Reduce32(c, M);
uint[] S = Y1Squared;
SecP192R1Field.Multiply(Y1Squared, X1.x, S);
c = Nat.ShiftUpBits(6, S, 2, 0);
SecP192R1Field.Reduce32(c, S);
c = Nat.ShiftUpBits(6, T, 3, 0, t1);
SecP192R1Field.Reduce32(c, t1);
SecP192R1FieldElement X3 = new SecP192R1FieldElement(T);
SecP192R1Field.Square(M, X3.x);
SecP192R1Field.Subtract(X3.x, S, X3.x);
SecP192R1Field.Subtract(X3.x, S, X3.x);
SecP192R1FieldElement Y3 = new SecP192R1FieldElement(S);
SecP192R1Field.Subtract(S, X3.x, Y3.x);
SecP192R1Field.Multiply(Y3.x, M, Y3.x);
SecP192R1Field.Subtract(Y3.x, t1, Y3.x);
SecP192R1FieldElement Z3 = new SecP192R1FieldElement(M);
SecP192R1Field.Twice(Y1.x, Z3.x);
if (!Z1IsOne)
{
SecP192R1Field.Multiply(Z3.x, Z1.x, Z3.x);
}
return new SecP192R1Point(curve, X3, Y3, new ECFieldElement[] { Z3 });
}
public override ECPoint TwicePlus(ECPoint b)
{
if (this == b)
return ThreeTimes();
if (this.IsInfinity)
return b;
if (b.IsInfinity)
return Twice();
ECFieldElement Y1 = this.RawYCoord;
if (Y1.IsZero)
return b;
return Twice().Add(b);
}
public override ECPoint ThreeTimes()
{
if (this.IsInfinity || this.RawYCoord.IsZero)
return this;
// NOTE: Be careful about recursions between TwicePlus and ThreeTimes
return Twice().Add(this);
}
public override ECPoint Negate()
{
if (IsInfinity)
return this;
return new SecP192R1Point(Curve, RawXCoord, RawYCoord.Negate(), RawZCoords);
}
}
}
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