using System; using Org.BouncyCastle.Math.Raw; namespace Org.BouncyCastle.Math.EC.Custom.Sec { internal class SecP521R1Point : AbstractFpPoint { /** * Create a point which encodes with point compression. * * @param curve * the curve to use * @param x * affine x co-ordinate * @param y * affine y co-ordinate * * @deprecated Use ECCurve.createPoint to construct points */ public SecP521R1Point(ECCurve curve, ECFieldElement x, ECFieldElement y) : this(curve, x, y, false) { } /** * Create a point that encodes with or without point compresion. * * @param curve * the curve to use * @param x * affine x co-ordinate * @param y * affine y co-ordinate * @param withCompression * if true encode with point compression * * @deprecated per-point compression property will be removed, refer * {@link #getEncoded(bool)} */ public SecP521R1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, bool withCompression) : base(curve, x, y, withCompression) { if ((x == null) != (y == null)) throw new ArgumentException("Exactly one of the field elements is null"); } internal SecP521R1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, ECFieldElement[] zs, bool withCompression) : base(curve, x, y, zs, withCompression) { } protected override ECPoint Detach() { return new SecP521R1Point(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; SecP521R1FieldElement X1 = (SecP521R1FieldElement)this.RawXCoord, Y1 = (SecP521R1FieldElement)this.RawYCoord; SecP521R1FieldElement X2 = (SecP521R1FieldElement)b.RawXCoord, Y2 = (SecP521R1FieldElement)b.RawYCoord; SecP521R1FieldElement Z1 = (SecP521R1FieldElement)this.RawZCoords[0]; SecP521R1FieldElement Z2 = (SecP521R1FieldElement)b.RawZCoords[0]; uint[] t1 = Nat.Create(17); uint[] t2 = Nat.Create(17); uint[] t3 = Nat.Create(17); uint[] t4 = Nat.Create(17); bool Z1IsOne = Z1.IsOne; uint[] U2, S2; if (Z1IsOne) { U2 = X2.x; S2 = Y2.x; } else { S2 = t3; SecP521R1Field.Square(Z1.x, S2); U2 = t2; SecP521R1Field.Multiply(S2, X2.x, U2); SecP521R1Field.Multiply(S2, Z1.x, S2); SecP521R1Field.Multiply(S2, Y2.x, S2); } bool Z2IsOne = Z2.IsOne; uint[] U1, S1; if (Z2IsOne) { U1 = X1.x; S1 = Y1.x; } else { S1 = t4; SecP521R1Field.Square(Z2.x, S1); U1 = t1; SecP521R1Field.Multiply(S1, X1.x, U1); SecP521R1Field.Multiply(S1, Z2.x, S1); SecP521R1Field.Multiply(S1, Y1.x, S1); } uint[] H = Nat.Create(17); SecP521R1Field.Subtract(U1, U2, H); uint[] R = t2; SecP521R1Field.Subtract(S1, S2, R); // Check if b == this or b == -this if (Nat.IsZero(17, H)) { if (Nat.IsZero(17, 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; SecP521R1Field.Square(H, HSquared); uint[] G = Nat.Create(17); SecP521R1Field.Multiply(HSquared, H, G); uint[] V = t3; SecP521R1Field.Multiply(HSquared, U1, V); SecP521R1Field.Multiply(S1, G, t1); SecP521R1FieldElement X3 = new SecP521R1FieldElement(t4); SecP521R1Field.Square(R, X3.x); SecP521R1Field.Add(X3.x, G, X3.x); SecP521R1Field.Subtract(X3.x, V, X3.x); SecP521R1Field.Subtract(X3.x, V, X3.x); SecP521R1FieldElement Y3 = new SecP521R1FieldElement(G); SecP521R1Field.Subtract(V, X3.x, Y3.x); SecP521R1Field.Multiply(Y3.x, R, t2); SecP521R1Field.Subtract(t2, t1, Y3.x); SecP521R1FieldElement Z3 = new SecP521R1FieldElement(H); if (!Z1IsOne) { SecP521R1Field.Multiply(Z3.x, Z1.x, Z3.x); } if (!Z2IsOne) { SecP521R1Field.Multiply(Z3.x, Z2.x, Z3.x); } ECFieldElement[] zs = new ECFieldElement[] { Z3 }; return new SecP521R1Point(curve, X3, Y3, zs, IsCompressed); } public override ECPoint Twice() { if (this.IsInfinity) return this; ECCurve curve = this.Curve; SecP521R1FieldElement Y1 = (SecP521R1FieldElement)this.RawYCoord; if (Y1.IsZero) return curve.Infinity; SecP521R1FieldElement X1 = (SecP521R1FieldElement)this.RawXCoord, Z1 = (SecP521R1FieldElement)this.RawZCoords[0]; uint[] t1 = Nat.Create(17); uint[] t2 = Nat.Create(17); uint[] Y1Squared = Nat.Create(17); SecP521R1Field.Square(Y1.x, Y1Squared); uint[] T = Nat.Create(17); SecP521R1Field.Square(Y1Squared, T); bool Z1IsOne = Z1.IsOne; uint[] Z1Squared = Z1.x; if (!Z1IsOne) { Z1Squared = t2; SecP521R1Field.Square(Z1.x, Z1Squared); } SecP521R1Field.Subtract(X1.x, Z1Squared, t1); uint[] M = t2; SecP521R1Field.Add(X1.x, Z1Squared, M); SecP521R1Field.Multiply(M, t1, M); Nat.AddBothTo(17, M, M, M); SecP521R1Field.Reduce23(M); uint[] S = Y1Squared; SecP521R1Field.Multiply(Y1Squared, X1.x, S); Nat.ShiftUpBits(17, S, 2, 0); SecP521R1Field.Reduce23(S); Nat.ShiftUpBits(17, T, 3, 0, t1); SecP521R1Field.Reduce23(t1); SecP521R1FieldElement X3 = new SecP521R1FieldElement(T); SecP521R1Field.Square(M, X3.x); SecP521R1Field.Subtract(X3.x, S, X3.x); SecP521R1Field.Subtract(X3.x, S, X3.x); SecP521R1FieldElement Y3 = new SecP521R1FieldElement(S); SecP521R1Field.Subtract(S, X3.x, Y3.x); SecP521R1Field.Multiply(Y3.x, M, Y3.x); SecP521R1Field.Subtract(Y3.x, t1, Y3.x); SecP521R1FieldElement Z3 = new SecP521R1FieldElement(M); SecP521R1Field.Twice(Y1.x, Z3.x); if (!Z1IsOne) { SecP521R1Field.Multiply(Z3.x, Z1.x, Z3.x); } return new SecP521R1Point(curve, X3, Y3, new ECFieldElement[] { Z3 }, IsCompressed); } 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 SecP521R1Point(Curve, RawXCoord, RawYCoord.Negate(), RawZCoords, IsCompressed); } } }