1 /* 2 * Copyright (c) 2003, 2013, 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 import java.util.Arrays; 29 30 /** 31 * This immutable class defines an elliptic curve (EC) prime 32 * finite field. 33 * 34 * @see ECField 35 * 36 * @author Valerie Peng 37 * 38 * @since 1.5 39 */ 40 public class ECFieldFp implements ECField { 41 42 private BigInteger p; 43 44 /** 45 * Creates an elliptic curve prime finite field 46 * with the specified prime {@code p}. 47 * @param p the prime. 48 * @exception NullPointerException if {@code p} is null. 49 * @exception IllegalArgumentException if {@code p} 50 * is not positive. 51 */ ECFieldFp(BigInteger p)52 public ECFieldFp(BigInteger p) { 53 if (p.signum() != 1) { 54 throw new IllegalArgumentException("p is not positive"); 55 } 56 this.p = p; 57 } 58 59 /** 60 * Returns the field size in bits which is size of prime p 61 * for this prime finite field. 62 * @return the field size in bits. 63 */ getFieldSize()64 public int getFieldSize() { 65 return p.bitLength(); 66 }; 67 68 /** 69 * Returns the prime {@code p} of this prime finite field. 70 * @return the prime. 71 */ getP()72 public BigInteger getP() { 73 return p; 74 } 75 76 /** 77 * Compares this prime finite field for equality with the 78 * specified object. 79 * @param obj the object to be compared. 80 * @return true if {@code obj} is an instance 81 * of ECFieldFp and the prime value match, false otherwise. 82 */ equals(Object obj)83 public boolean equals(Object obj) { 84 if (this == obj) return true; 85 if (obj instanceof ECFieldFp) { 86 return (p.equals(((ECFieldFp)obj).p)); 87 } 88 return false; 89 } 90 91 /** 92 * Returns a hash code value for this prime finite field. 93 * @return a hash code value. 94 */ hashCode()95 public int hashCode() { 96 return p.hashCode(); 97 } 98 } 99