/*

 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.security.interfaces;

import java.math.BigInteger;

import java.security.PublicKey;

/**

 * An interface for an elliptic curve public key as defined by RFC 7748.

 * These keys are distinct from the keys represented by {@code ECPublicKey},

 * and they are intended for use with algorithms based on RFC 7748 such as the

 * XDH {@code KeyAgreement} algorithm.

 *

 * An XEC public key is a particular point on the curve, which is represented

 * using only its u-coordinate as described in RFC 7748. A u-coordinate is an

 * element of the field of integers modulo some value that is determined by

 * the algorithm parameters. This field element is represented by a BigInteger

 * which may hold any value. That is, the BigInteger is not restricted to the

 * range of canonical field elements.

 *

 * @since 11

 */

public interface XECPublicKey extends XECKey, PublicKey {

    /**

     * Get the u coordinate of the point.

     *

     * @return the u-coordinate, represented using a BigInteger which may hold

     *          any value

     */

    BigInteger getU();

}