public override ECFieldElement Add(ECFieldElement b)
 {
     uint[] z = Nat256.Create();
     SecP256R1Field.Add(x, ((SecP256R1FieldElement)b).x, z);
     return(new SecP256R1FieldElement(z));
 }
Beispiel #2
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        public override ECPoint Twice()
        {
            if (this.IsInfinity)
            {
                return(this);
            }

            ECCurve curve = this.Curve;

            SecP256R1FieldElement Y1 = (SecP256R1FieldElement)this.RawYCoord;

            if (Y1.IsZero)
            {
                return(curve.Infinity);
            }

            SecP256R1FieldElement X1 = (SecP256R1FieldElement)this.RawXCoord, Z1 = (SecP256R1FieldElement)this.RawZCoords[0];

            uint c;

            uint[] t1 = Nat256.Create();
            uint[] t2 = Nat256.Create();

            uint[] Y1Squared = Nat256.Create();
            SecP256R1Field.Square(Y1.x, Y1Squared);

            uint[] T = Nat256.Create();
            SecP256R1Field.Square(Y1Squared, T);

            bool Z1IsOne = Z1.IsOne;

            uint[] Z1Squared = Z1.x;
            if (!Z1IsOne)
            {
                Z1Squared = t2;
                SecP256R1Field.Square(Z1.x, Z1Squared);
            }

            SecP256R1Field.Subtract(X1.x, Z1Squared, t1);

            uint[] M = t2;
            SecP256R1Field.Add(X1.x, Z1Squared, M);
            SecP256R1Field.Multiply(M, t1, M);
            c = Nat256.AddBothTo(M, M, M);
            SecP256R1Field.Reduce32(c, M);

            uint[] S = Y1Squared;
            SecP256R1Field.Multiply(Y1Squared, X1.x, S);
            c = Nat.ShiftUpBits(8, S, 2, 0);
            SecP256R1Field.Reduce32(c, S);

            c = Nat.ShiftUpBits(8, T, 3, 0, t1);
            SecP256R1Field.Reduce32(c, t1);

            SecP256R1FieldElement X3 = new SecP256R1FieldElement(T);

            SecP256R1Field.Square(M, X3.x);
            SecP256R1Field.Subtract(X3.x, S, X3.x);
            SecP256R1Field.Subtract(X3.x, S, X3.x);

            SecP256R1FieldElement Y3 = new SecP256R1FieldElement(S);

            SecP256R1Field.Subtract(S, X3.x, Y3.x);
            SecP256R1Field.Multiply(Y3.x, M, Y3.x);
            SecP256R1Field.Subtract(Y3.x, t1, Y3.x);

            SecP256R1FieldElement Z3 = new SecP256R1FieldElement(M);

            SecP256R1Field.Twice(Y1.x, Z3.x);
            if (!Z1IsOne)
            {
                SecP256R1Field.Multiply(Z3.x, Z1.x, Z3.x);
            }

            return(new SecP256R1Point(curve, X3, Y3, new ECFieldElement[] { Z3 }, IsCompressed));
        }