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org.bouncycastle.math.ec.custom.sec.SecT571K1Point Maven / Gradle / Ivy
package org.bouncycastle.math.ec.custom.sec;
import org.bouncycastle.math.ec.ECConstants;
import org.bouncycastle.math.ec.ECCurve;
import org.bouncycastle.math.ec.ECFieldElement;
import org.bouncycastle.math.ec.ECPoint;
import org.bouncycastle.math.ec.ECPoint.AbstractF2m;
import org.bouncycastle.math.raw.Nat576;
public class SecT571K1Point extends AbstractF2m
{
SecT571K1Point(ECCurve curve, ECFieldElement x, ECFieldElement y)
{
super(curve, x, y);
}
SecT571K1Point(ECCurve curve, ECFieldElement x, ECFieldElement y, ECFieldElement[] zs)
{
super(curve, x, y, zs);
}
protected ECPoint detach()
{
return new SecT571K1Point(null, this.getAffineXCoord(), this.getAffineYCoord()); // earlier JDK
}
public ECFieldElement getYCoord()
{
ECFieldElement X = x, L = y;
if (this.isInfinity() || X.isZero())
{
return L;
}
// Y is actually Lambda (X + Y/X) here; convert to affine value on the fly
ECFieldElement Y = L.add(X).multiply(X);
ECFieldElement Z = zs[0];
if (!Z.isOne())
{
Y = Y.divide(Z);
}
return Y;
}
protected boolean getCompressionYTilde()
{
ECFieldElement X = this.getRawXCoord();
if (X.isZero())
{
return false;
}
ECFieldElement Y = this.getRawYCoord();
// Y is actually Lambda (X + Y/X) here
return Y.testBitZero() != X.testBitZero();
}
public ECPoint add(ECPoint b)
{
if (this.isInfinity())
{
return b;
}
if (b.isInfinity())
{
return this;
}
ECCurve curve = this.getCurve();
SecT571FieldElement X1 = (SecT571FieldElement)this.x;
SecT571FieldElement X2 = (SecT571FieldElement)b.getRawXCoord();
if (X1.isZero())
{
if (X2.isZero())
{
return curve.getInfinity();
}
return b.add(this);
}
SecT571FieldElement L1 = (SecT571FieldElement)this.y, Z1 = (SecT571FieldElement)this.zs[0];
SecT571FieldElement L2 = (SecT571FieldElement)b.getRawYCoord(), Z2 = (SecT571FieldElement)b.getZCoord(0);
long[] t1 = Nat576.create64();
long[] t2 = Nat576.create64();
long[] t3 = Nat576.create64();
long[] t4 = Nat576.create64();
long[] Z1Precomp = Z1.isOne() ? null : SecT571Field.precompMultiplicand(Z1.x);
long[] U2, S2;
if (Z1Precomp == null)
{
U2 = X2.x;
S2 = L2.x;
}
else
{
SecT571Field.multiplyPrecomp(X2.x, Z1Precomp, U2 = t2);
SecT571Field.multiplyPrecomp(L2.x, Z1Precomp, S2 = t4);
}
long[] Z2Precomp = Z2.isOne() ? null : SecT571Field.precompMultiplicand(Z2.x);
long[] U1, S1;
if (Z2Precomp == null)
{
U1 = X1.x;
S1 = L1.x;
}
else
{
SecT571Field.multiplyPrecomp(X1.x, Z2Precomp, U1 = t1);
SecT571Field.multiplyPrecomp(L1.x, Z2Precomp, S1 = t3);
}
long[] A = t3;
SecT571Field.add(S1, S2, A);
long[] B = t4;
SecT571Field.add(U1, U2, B);
if (Nat576.isZero64(B))
{
if (Nat576.isZero64(A))
{
return twice();
}
return curve.getInfinity();
}
SecT571FieldElement X3, L3, Z3;
if (X2.isZero())
{
// TODO This can probably be optimized quite a bit
ECPoint p = this.normalize();
X1 = (SecT571FieldElement)p.getXCoord();
ECFieldElement Y1 = p.getYCoord();
ECFieldElement Y2 = L2;
ECFieldElement L = Y1.add(Y2).divide(X1);
X3 = (SecT571FieldElement)L.square().add(L).add(X1);
if (X3.isZero())
{
return new SecT571K1Point(curve, X3, curve.getB());
}
ECFieldElement Y3 = L.multiply(X1.add(X3)).add(X3).add(Y1);
L3 = (SecT571FieldElement)Y3.divide(X3).add(X3);
Z3 = (SecT571FieldElement)curve.fromBigInteger(ECConstants.ONE);
}
else
{
SecT571Field.square(B, B);
long[] APrecomp = SecT571Field.precompMultiplicand(A);
long[] AU1 = t1;
long[] AU2 = t2;
SecT571Field.multiplyPrecomp(U1, APrecomp, AU1);
SecT571Field.multiplyPrecomp(U2, APrecomp, AU2);
X3 = new SecT571FieldElement(t1);
SecT571Field.multiply(AU1, AU2, X3.x);
if (X3.isZero())
{
return new SecT571K1Point(curve, X3, curve.getB());
}
Z3 = new SecT571FieldElement(t3);
SecT571Field.multiplyPrecomp(B, APrecomp, Z3.x);
if (Z2Precomp != null)
{
SecT571Field.multiplyPrecomp(Z3.x, Z2Precomp, Z3.x);
}
long[] tt = Nat576.createExt64();
SecT571Field.add(AU2, B, t4);
SecT571Field.squareAddToExt(t4, tt);
SecT571Field.add(L1.x, Z1.x, t4);
SecT571Field.multiplyAddToExt(t4, Z3.x, tt);
L3 = new SecT571FieldElement(t4);
SecT571Field.reduce(tt, L3.x);
if (Z1Precomp != null)
{
SecT571Field.multiplyPrecomp(Z3.x, Z1Precomp, Z3.x);
}
}
return new SecT571K1Point(curve, X3, L3, new ECFieldElement[]{ Z3 });
}
public ECPoint twice()
{
if (this.isInfinity())
{
return this;
}
ECCurve curve = this.getCurve();
ECFieldElement X1 = this.x;
if (X1.isZero())
{
// A point with X == 0 is its own additive inverse
return curve.getInfinity();
}
ECFieldElement L1 = this.y, Z1 = this.zs[0];
boolean Z1IsOne = Z1.isOne();
ECFieldElement Z1Sq = Z1IsOne ? Z1 : Z1.square();
ECFieldElement T;
if (Z1IsOne)
{
T = L1.square().add(L1);
}
else
{
T = L1.add(Z1).multiply(L1);
}
if (T.isZero())
{
return new SecT571K1Point(curve, T, curve.getB());
}
ECFieldElement X3 = T.square();
ECFieldElement Z3 = Z1IsOne ? T : T.multiply(Z1Sq);
ECFieldElement t1 = L1.add(X1).square();
ECFieldElement t2 = Z1IsOne ? Z1 : Z1Sq.square();
ECFieldElement L3 = t1.add(T).add(Z1Sq).multiply(t1).add(t2).add(X3).add(Z3);
return new SecT571K1Point(curve, X3, L3, new ECFieldElement[]{ Z3 });
}
public ECPoint twicePlus(ECPoint b)
{
if (this.isInfinity())
{
return b;
}
if (b.isInfinity())
{
return twice();
}
ECCurve curve = this.getCurve();
ECFieldElement X1 = this.x;
if (X1.isZero())
{
// A point with X == 0 is its own additive inverse
return b;
}
// NOTE: twicePlus() only optimized for lambda-affine argument
ECFieldElement X2 = b.getRawXCoord(), Z2 = b.getZCoord(0);
if (X2.isZero() || !Z2.isOne())
{
return twice().add(b);
}
ECFieldElement L1 = this.y, Z1 = this.zs[0];
ECFieldElement L2 = b.getRawYCoord();
ECFieldElement X1Sq = X1.square();
ECFieldElement L1Sq = L1.square();
ECFieldElement Z1Sq = Z1.square();
ECFieldElement L1Z1 = L1.multiply(Z1);
ECFieldElement T = L1Sq.add(L1Z1);
ECFieldElement L2plus1 = L2.addOne();
ECFieldElement A = L2plus1.multiply(Z1Sq).add(L1Sq).multiplyPlusProduct(T, X1Sq, Z1Sq);
ECFieldElement X2Z1Sq = X2.multiply(Z1Sq);
ECFieldElement B = X2Z1Sq.add(T).square();
if (B.isZero())
{
if (A.isZero())
{
return b.twice();
}
return curve.getInfinity();
}
if (A.isZero())
{
return new SecT571K1Point(curve, A, curve.getB());
}
ECFieldElement X3 = A.square().multiply(X2Z1Sq);
ECFieldElement Z3 = A.multiply(B).multiply(Z1Sq);
ECFieldElement L3 = A.add(B).square().multiplyPlusProduct(T, L2plus1, Z3);
return new SecT571K1Point(curve, X3, L3, new ECFieldElement[]{ Z3 });
}
public ECPoint negate()
{
if (this.isInfinity())
{
return this;
}
ECFieldElement X = this.x;
if (X.isZero())
{
return this;
}
// L is actually Lambda (X + Y/X) here
ECFieldElement L = this.y, Z = this.zs[0];
return new SecT571K1Point(curve, X, L.add(Z), new ECFieldElement[]{ Z });
}
}
