/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package java.security.spec;
import java.math.BigInteger;
/**
* A Point on an Elliptic Curve in barycentric (or affine) coordinates.
*/
public class ECPoint {
/**
* The point on an Elliptic Curve at infinity.
*/
public static final ECPoint POINT_INFINITY = new ECPoint();
// affine X coordinate of this point
private final BigInteger affineX;
// affine Y coordinate of this point
private final BigInteger affineY;
// Private ctor for POINT_INFINITY
private ECPoint() {
affineX = null;
affineY = null;
}
/**
* Creates a new point at the specified coordinates.
*
* @param affineX
* the x-coordinate.
* @param affineY
* the y-coordinate.
*/
public ECPoint(BigInteger affineX, BigInteger affineY) {
this.affineX = affineX;
if (this.affineX == null) {
throw new NullPointerException("affineX == null");
}
this.affineY = affineY;
if (this.affineY == null) {
throw new NullPointerException("affineY == null");
}
}
/**
* Returns the x-coordinate.
*
* @return the x-coordinate, or {@code null} for the infinite point.
*/
public BigInteger getAffineX() {
return affineX;
}
/**
* Returns the y-coordinate.
*
* @return the y-coordinate, or {@code null} fot the infinite point.
*/
public BigInteger getAffineY() {
return affineY;
}
/**
* Returns whether the specified object and this elliptic curve point are
* equal.
*
* @param other
* the object to compare.
* @return {@code true} if the specified object and this elliptic curve
* point are equal, otherwise {@code false}.
*/
public boolean equals(Object other) {
if (this == other) {
return true;
}
if (other instanceof ECPoint) {
if (this.affineX != null) {
ECPoint otherPoint = (ECPoint)other;
// no need to check for null in this case
return this.affineX.equals(otherPoint.affineX) &&
this.affineY.equals(otherPoint.affineY);
} else {
return other == POINT_INFINITY;
}
}
return false;
}
/**
* Returns the hashcode of this elliptic curve point.
*
* @return the hashcode of this elliptic curve point.
*/
public int hashCode() {
if (this.affineX != null) {
return affineX.hashCode() * 31 + affineY.hashCode();
}
return 11;
}
}