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.Nat224;
public class SecP224K1Point extends ECPoint.AbstractFp
{
/**
* 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 SecP224K1Point(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(boolean)}
*/
public SecP224K1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, boolean withCompression)
{
super(curve, x, y);
if ((x == null) != (y == null))
{
throw new IllegalArgumentException("Exactly one of the field elements is null");
}
this.withCompression = withCompression;
}
SecP224K1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, ECFieldElement[] zs,
boolean withCompression)
{
super(curve, x, y, zs);
this.withCompression = withCompression;
}
protected ECPoint detach()
{
return new SecP224K1Point(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();
SecP224K1FieldElement X1 = (SecP224K1FieldElement)this.x, Y1 = (SecP224K1FieldElement)this.y;
SecP224K1FieldElement X2 = (SecP224K1FieldElement)b.getXCoord(), Y2 = (SecP224K1FieldElement)b.getYCoord();
SecP224K1FieldElement Z1 = (SecP224K1FieldElement)this.zs[0];
SecP224K1FieldElement Z2 = (SecP224K1FieldElement)b.getZCoord(0);
int c;
int[] tt1 = Nat224.createExt();
int[] t2 = Nat224.create();
int[] t3 = Nat224.create();
int[] t4 = Nat224.create();
boolean Z1IsOne = Z1.isOne();
int[] U2, S2;
if (Z1IsOne)
{
U2 = X2.x;
S2 = Y2.x;
}
else
{
S2 = t3;
SecP224K1Field.square(Z1.x, S2);
U2 = t2;
SecP224K1Field.multiply(S2, X2.x, U2);
SecP224K1Field.multiply(S2, Z1.x, S2);
SecP224K1Field.multiply(S2, Y2.x, S2);
}
boolean Z2IsOne = Z2.isOne();
int[] U1, S1;
if (Z2IsOne)
{
U1 = X1.x;
S1 = Y1.x;
}
else
{
S1 = t4;
SecP224K1Field.square(Z2.x, S1);
U1 = tt1;
SecP224K1Field.multiply(S1, X1.x, U1);
SecP224K1Field.multiply(S1, Z2.x, S1);
SecP224K1Field.multiply(S1, Y1.x, S1);
}
int[] H = Nat224.create();
SecP224K1Field.subtract(U1, U2, H);
int[] R = t2;
SecP224K1Field.subtract(S1, S2, R);
// Check if b == this or b == -this
if (Nat224.isZero(H))
{
if (Nat224.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;
SecP224K1Field.square(H, HSquared);
int[] G = Nat224.create();
SecP224K1Field.multiply(HSquared, H, G);
int[] V = t3;
SecP224K1Field.multiply(HSquared, U1, V);
SecP224K1Field.negate(G, G);
Nat224.mul(S1, G, tt1);
c = Nat224.addBothTo(V, V, G);
SecP224K1Field.reduce32(c, G);
SecP224K1FieldElement X3 = new SecP224K1FieldElement(t4);
SecP224K1Field.square(R, X3.x);
SecP224K1Field.subtract(X3.x, G, X3.x);
SecP224K1FieldElement Y3 = new SecP224K1FieldElement(G);
SecP224K1Field.subtract(V, X3.x, Y3.x);
SecP224K1Field.multiplyAddToExt(Y3.x, R, tt1);
SecP224K1Field.reduce(tt1, Y3.x);
SecP224K1FieldElement Z3 = new SecP224K1FieldElement(H);
if (!Z1IsOne)
{
SecP224K1Field.multiply(Z3.x, Z1.x, Z3.x);
}
if (!Z2IsOne)
{
SecP224K1Field.multiply(Z3.x, Z2.x, Z3.x);
}
ECFieldElement[] zs = new ECFieldElement[] { Z3 };
return new SecP224K1Point(curve, X3, Y3, zs, this.withCompression);
}
// B.3 pg 62
public ECPoint twice()
{
if (this.isInfinity())
{
return this;
}
ECCurve curve = this.getCurve();
SecP224K1FieldElement Y1 = (SecP224K1FieldElement)this.y;
if (Y1.isZero())
{
return curve.getInfinity();
}
SecP224K1FieldElement X1 = (SecP224K1FieldElement)this.x, Z1 = (SecP224K1FieldElement)this.zs[0];
int c;
int[] Y1Squared = Nat224.create();
SecP224K1Field.square(Y1.x, Y1Squared);
int[] T = Nat224.create();
SecP224K1Field.square(Y1Squared, T);
int[] M = Nat224.create();
SecP224K1Field.square(X1.x, M);
c = Nat224.addBothTo(M, M, M);
SecP224K1Field.reduce32(c, M);
int[] S = Y1Squared;
SecP224K1Field.multiply(Y1Squared, X1.x, S);
c = Nat.shiftUpBits(7, S, 2, 0);
SecP224K1Field.reduce32(c, S);
int[] t1 = Nat224.create();
c = Nat.shiftUpBits(7, T, 3, 0, t1);
SecP224K1Field.reduce32(c, t1);
SecP224K1FieldElement X3 = new SecP224K1FieldElement(T);
SecP224K1Field.square(M, X3.x);
SecP224K1Field.subtract(X3.x, S, X3.x);
SecP224K1Field.subtract(X3.x, S, X3.x);
SecP224K1FieldElement Y3 = new SecP224K1FieldElement(S);
SecP224K1Field.subtract(S, X3.x, Y3.x);
SecP224K1Field.multiply(Y3.x, M, Y3.x);
SecP224K1Field.subtract(Y3.x, t1, Y3.x);
SecP224K1FieldElement Z3 = new SecP224K1FieldElement(M);
SecP224K1Field.twice(Y1.x, Z3.x);
if (!Z1.isOne())
{
SecP224K1Field.multiply(Z3.x, Z1.x, Z3.x);
}
return new SecP224K1Point(curve, X3, Y3, new ECFieldElement[] { Z3 }, this.withCompression);
}
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 SecP224K1Point(curve, this.x, this.y.negate(), this.zs, this.withCompression);
}
}