java.security.spec.ECFieldFp Maven / Gradle / Ivy
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* 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;
/**
* The parameters specifying a prime finite field of an
* elliptic curve.
*/
public class ECFieldFp implements ECField {
// Prime
private final BigInteger p;
/**
* Creates a new prime finite field of an elliptic curve with the specified
* prime {@code p}.
*
* @param p
* the prime value {@code p}.
* @throws IllegalArgumentException
* if {@code p <= zero}.
*/
public ECFieldFp(BigInteger p) {
this.p = p;
if (this.p == null) {
throw new NullPointerException("p == null");
}
if (this.p.signum() != 1) {
throw new IllegalArgumentException("p <= 0");
}
}
/**
* Returns the size of the finite field (in bits).
*
* @return the size of the finite field (in bits).
*/
public int getFieldSize() {
return p.bitLength();
}
/**
* Returns the prime value {@code p} for this finite field.
*
* @return the prime value {@code p} for this finite field.
*/
public BigInteger getP() {
return p;
}
/**
* Returns whether the specified object is equal to this finite field.
*
* @param obj
* the object to compare to this finite field.
* @return {@code true} if the specified object is equal to this finite field,
* otherwise {@code false}.
*/
public boolean equals(Object obj) {
// object equals itself
if (this == obj) {
return true;
}
if (obj instanceof ECFieldFp) {
return (this.p.equals(((ECFieldFp)obj).p));
}
return false;
}
/**
* Returns the hashcode value for this finite field.
*
* @return the hashcode value for this finite field.
*/
public int hashCode() {
return p.hashCode();
}
}