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| 1 | +/* | |
| 2 | + * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved. | |
| 3 | + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 | + * | |
| 5 | + * This code is free software; you can redistribute it and/or modify it | |
| 6 | + * under the terms of the GNU General Public License version 2 only, as | |
| 7 | + * published by the Free Software Foundation. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle in the LICENSE file that accompanied this code. | |
| 10 | + * | |
| 11 | + * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 12 | + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 13 | + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 14 | + * version 2 for more details (a copy is included in the LICENSE file that | |
| 15 | + * accompanied this code). | |
| 16 | + * | |
| 17 | + * You should have received a copy of the GNU General Public License version | |
| 18 | + * 2 along with this work; if not, write to the Free Software Foundation, | |
| 19 | + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 20 | + * | |
| 21 | + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * questions. | |
| 24 | + */ | |
| 25 | +package java.security.spec; | |
| 26 | + | |
| 27 | +import java.math.BigInteger; | |
| 28 | + | |
| 29 | +/** | |
| 30 | + * This immutable class represents a point on an elliptic curve (EC) | |
| 31 | + * in affine coordinates. Other coordinate systems can | |
| 32 | + * extend this class to represent this point in other | |
| 33 | + * coordinates. | |
| 34 | + * | |
| 35 | + * @author Valerie Peng | |
| 36 | + * | |
| 37 | + * @since 1.5 | |
| 38 | + */ | |
| 39 | +public class ECPoint { | |
| 40 | + | |
| 41 | + private final BigInteger x; | |
| 42 | + private final BigInteger y; | |
| 43 | + | |
| 44 | + /** | |
| 45 | + * This defines the point at infinity. | |
| 46 | + */ | |
| 47 | + public static final ECPoint POINT_INFINITY = new ECPoint(); | |
| 48 | + | |
| 49 | + // private constructor for constructing point at infinity | |
| 50 | + private ECPoint() { | |
| 51 | + this.x = null; | |
| 52 | + this.y = null; | |
| 53 | + } | |
| 54 | + | |
| 55 | + /** | |
| 56 | + * Creates an ECPoint from the specified affine x-coordinate | |
| 57 | + * <code>x</code> and affine y-coordinate <code>y</code>. | |
| 58 | + * @param x the affine x-coordinate. | |
| 59 | + * @param y the affine y-coordinate. | |
| 60 | + * @exception NullPointerException if <code>x</code> or | |
| 61 | + * <code>y</code> is null. | |
| 62 | + */ | |
| 63 | + public ECPoint(BigInteger x, BigInteger y) { | |
| 64 | + if ((x==null) || (y==null)) { | |
| 65 | + throw new NullPointerException("affine coordinate x or y is null"); | |
| 66 | + } | |
| 67 | + this.x = x; | |
| 68 | + this.y = y; | |
| 69 | + } | |
| 70 | + | |
| 71 | + /** | |
| 72 | + * Returns the affine x-coordinate <code>x</code>. | |
| 73 | + * Note: POINT_INFINITY has a null affine x-coordinate. | |
| 74 | + * @return the affine x-coordinate. | |
| 75 | + */ | |
| 76 | + public BigInteger getAffineX() { | |
| 77 | + return x; | |
| 78 | + } | |
| 79 | + | |
| 80 | + /** | |
| 81 | + * Returns the affine y-coordinate <code>y</code>. | |
| 82 | + * Note: POINT_INFINITY has a null affine y-coordinate. | |
| 83 | + * @return the affine y-coordinate. | |
| 84 | + */ | |
| 85 | + public BigInteger getAffineY() { | |
| 86 | + return y; | |
| 87 | + } | |
| 88 | + | |
| 89 | + /** | |
| 90 | + * Compares this elliptic curve point for equality with | |
| 91 | + * the specified object. | |
| 92 | + * @param obj the object to be compared. | |
| 93 | + * @return true if <code>obj</code> is an instance of | |
| 94 | + * ECPoint and the affine coordinates match, false otherwise. | |
| 95 | + */ | |
| 96 | + public boolean equals(Object obj) { | |
| 97 | + if (this == obj) return true; | |
| 98 | + if (this == POINT_INFINITY) return false; | |
| 99 | + if (obj instanceof ECPoint) { | |
| 100 | + return ((x.equals(((ECPoint)obj).x)) && | |
| 101 | + (y.equals(((ECPoint)obj).y))); | |
| 102 | + } | |
| 103 | + return false; | |
| 104 | + } | |
| 105 | + | |
| 106 | + /** | |
| 107 | + * Returns a hash code value for this elliptic curve point. | |
| 108 | + * @return a hash code value. | |
| 109 | + */ | |
| 110 | + public int hashCode() { | |
| 111 | + if (this == POINT_INFINITY) return 0; | |
| 112 | + return x.hashCode() << 5 + y.hashCode(); | |
| 113 | + } | |
| 114 | +} | |