org.bouncycastle.math.ec.custom.sec.SecP160K1Point Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of bcprov-ext-debug-jdk18on Show documentation
The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for Java 1.8 and later with debug enabled.
The newest version!
package org.bouncycastle.math.ec.custom.sec;

import org.bouncycastle.math.ec.ECCurve;
import org.bouncycastle.math.ec.ECFieldElement;
import org.bouncycastle.math.ec.ECPoint;
import org.bouncycastle.math.raw.Nat;
import org.bouncycastle.math.raw.Nat160;

public class SecP160K1Point extends ECPoint.AbstractFp
{
    SecP160K1Point(ECCurve curve, ECFieldElement x, ECFieldElement y)
    {
        super(curve, x, y);
    }

    SecP160K1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, ECFieldElement[] zs)
    {
        super(curve, x, y, zs);
    }

    protected ECPoint detach()
    {
        return new SecP160K1Point(null, getAffineXCoord(), getAffineYCoord());
    }

    // B.3 pg 62
    public ECPoint add(ECPoint b)
    {
        if (this.isInfinity())
        {
            return b;
        }
        if (b.isInfinity())
        {
            return this;
        }
        if (this == b)
        {
            return twice();
        }

        ECCurve curve = this.getCurve();

        SecP160R2FieldElement X1 = (SecP160R2FieldElement)this.x, Y1 = (SecP160R2FieldElement)this.y;
        SecP160R2FieldElement X2 = (SecP160R2FieldElement)b.getXCoord(), Y2 = (SecP160R2FieldElement)b.getYCoord();

        SecP160R2FieldElement Z1 = (SecP160R2FieldElement)this.zs[0];
        SecP160R2FieldElement Z2 = (SecP160R2FieldElement)b.getZCoord(0);

        int c;
        int[] tt1 = Nat160.createExt();
        int[] t2 = Nat160.create();
        int[] t3 = Nat160.create();
        int[] t4 = Nat160.create();

        boolean Z1IsOne = Z1.isOne();
        int[] U2, S2;
        if (Z1IsOne)
        {
            U2 = X2.x;
            S2 = Y2.x;
        }
        else
        {
            S2 = t3;
            SecP160R2Field.square(Z1.x, S2);

            U2 = t2;
            SecP160R2Field.multiply(S2, X2.x, U2);

            SecP160R2Field.multiply(S2, Z1.x, S2);
            SecP160R2Field.multiply(S2, Y2.x, S2);
        }

        boolean Z2IsOne = Z2.isOne();
        int[] U1, S1;
        if (Z2IsOne)
        {
            U1 = X1.x;
            S1 = Y1.x;
        }
        else
        {
            S1 = t4;
            SecP160R2Field.square(Z2.x, S1);

            U1 = tt1;
            SecP160R2Field.multiply(S1, X1.x, U1);

            SecP160R2Field.multiply(S1, Z2.x, S1);
            SecP160R2Field.multiply(S1, Y1.x, S1);
        }

        int[] H = Nat160.create();
        SecP160R2Field.subtract(U1, U2, H);

        int[] R = t2;
        SecP160R2Field.subtract(S1, S2, R);

        // Check if b == this or b == -this
        if (Nat160.isZero(H))
        {
            if (Nat160.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.getInfinity();
        }

        int[] HSquared = t3;
        SecP160R2Field.square(H, HSquared);

        int[] G = Nat160.create();
        SecP160R2Field.multiply(HSquared, H, G);

        int[] V = t3;
        SecP160R2Field.multiply(HSquared, U1, V);

        SecP160R2Field.negate(G, G);
        Nat160.mul(S1, G, tt1);

        c = Nat160.addBothTo(V, V, G);
        SecP160R2Field.reduce32(c, G);

        SecP160R2FieldElement X3 = new SecP160R2FieldElement(t4);
        SecP160R2Field.square(R, X3.x);
        SecP160R2Field.subtract(X3.x, G, X3.x);

        SecP160R2FieldElement Y3 = new SecP160R2FieldElement(G);
        SecP160R2Field.subtract(V, X3.x, Y3.x);
        SecP160R2Field.multiplyAddToExt(Y3.x, R, tt1);
        SecP160R2Field.reduce(tt1, Y3.x);

        SecP160R2FieldElement Z3 = new SecP160R2FieldElement(H);
        if (!Z1IsOne)
        {
            SecP160R2Field.multiply(Z3.x, Z1.x, Z3.x);
        }
        if (!Z2IsOne)
        {
            SecP160R2Field.multiply(Z3.x, Z2.x, Z3.x);
        }

        ECFieldElement[] zs = new ECFieldElement[] { Z3 };

        return new SecP160K1Point(curve, X3, Y3, zs);
    }

    // B.3 pg 62
    public ECPoint twice()
    {
        if (this.isInfinity())
        {
            return this;
        }

        ECCurve curve = this.getCurve();

        SecP160R2FieldElement Y1 = (SecP160R2FieldElement)this.y;
        if (Y1.isZero())
        {
            return curve.getInfinity();
        }

        SecP160R2FieldElement X1 = (SecP160R2FieldElement)this.x, Z1 = (SecP160R2FieldElement)this.zs[0];

        int c;

        int[] Y1Squared = Nat160.create();
        SecP160R2Field.square(Y1.x, Y1Squared);

        int[] T = Nat160.create();
        SecP160R2Field.square(Y1Squared, T);

        int[] M = Nat160.create();
        SecP160R2Field.square(X1.x, M);
        c = Nat160.addBothTo(M, M, M);
        SecP160R2Field.reduce32(c, M);

        int[] S = Y1Squared;
        SecP160R2Field.multiply(Y1Squared, X1.x, S);
        c = Nat.shiftUpBits(5, S, 2, 0);
        SecP160R2Field.reduce32(c, S);

        int[] t1 = Nat160.create();
        c = Nat.shiftUpBits(5, T, 3, 0, t1);
        SecP160R2Field.reduce32(c, t1);

        SecP160R2FieldElement X3 = new SecP160R2FieldElement(T);
        SecP160R2Field.square(M, X3.x);
        SecP160R2Field.subtract(X3.x, S, X3.x);
        SecP160R2Field.subtract(X3.x, S, X3.x);

        SecP160R2FieldElement Y3 = new SecP160R2FieldElement(S);
        SecP160R2Field.subtract(S, X3.x, Y3.x);
        SecP160R2Field.multiply(Y3.x, M, Y3.x);
        SecP160R2Field.subtract(Y3.x, t1, Y3.x);

        SecP160R2FieldElement Z3 = new SecP160R2FieldElement(M);
        SecP160R2Field.twice(Y1.x, Z3.x);
        if (!Z1.isOne())
        {
            SecP160R2Field.multiply(Z3.x, Z1.x, Z3.x);
        }

        return new SecP160K1Point(curve, X3, Y3, new ECFieldElement[] { Z3 });
    }

    public ECPoint twicePlus(ECPoint b)
    {
        if (this == b)
        {
            return threeTimes();
        }
        if (this.isInfinity())
        {
            return b;
        }
        if (b.isInfinity())
        {
            return twice();
        }

        ECFieldElement Y1 = this.y;
        if (Y1.isZero())
        {
            return b;
        }

        return twice().add(b);
    }

    public ECPoint threeTimes()
    {
        if (this.isInfinity() || this.y.isZero())
        {
            return this;
        }

        // NOTE: Be careful about recursions between twicePlus and threeTimes
        return twice().add(this);
    }

    public ECPoint negate()
    {
        if (this.isInfinity())
        {
            return this;
        }

        return new SecP160K1Point(curve, this.x, this.y.negate(), this.zs);
    }
}