1 /*
   2  * Copyright (c) 2018, 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.interfaces;
  26 
  27 import java.security.PrivateKey;
  28 import java.util.Optional;
  29 
  30 /**
  31  * An XEC private key is an encoded scalar value as described in RFC 7748.
  32  * The decoding procedure defined in this RFC includes an operation that forces
  33  * certain bits of the key to either 1 or 0. This operation is known as
  34  * "pruning" or "clamping" the private key. Arrays returned by this interface
  35  * are unpruned, and implementations will need to prune the array before
  36  * using it in any numerical operations.
  37  *
  38  * @since 11
  39  */
  40 public interface XECPrivateKey extends XECKey, PrivateKey {
  41 
  42     /**
  43      * Get the scalar value encoded as an unpruned byte array. A new copy of
  44      * the array is returned each time this method is called.
  45      *
  46      * @return the unpruned encoded scalar value, or an empty Optional if the
  47      *     scalar cannot be extracted (e.g. if the provider is a hardware token
  48      *     and the private key is not allowed to leave the crypto boundary). 
  49      */
  50     Optional<byte[]> getScalar();
  51 }
  52