1 /*
   2  * Copyright (c) 1997, 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 
  26 package javax.crypto;
  27 
  28 /**
  29  * A secret (symmetric) key.
  30  * The purpose of this interface is to group (and provide type safety
  31  * for) all secret key interfaces.
  32  * <p>
  33  * Provider implementations of this interface must overwrite the
  34  * {@code equals} and {@code hashCode} methods inherited from
  35  * {@link java.lang.Object}, so that secret keys are compared based on
  36  * their underlying key material and not based on reference.
  37  * Implementations should override the default {@code destroy} and
  38  * {@code isDestroyed} methods from the
  39  * {@link javax.security.auth.Destroyable} interface to enable
  40  * sensitive key information to be destroyed, cleared, or in the case
  41  * where such information is immutable, unreferenced.
  42  * Finally, since {@code SecretKey} is {@code Serializable}, implementations
  43  * should also override
  44  * {@link java.io.ObjectOutputStream#writeObject(java.lang.Object)}
  45  * to prevent keys that have been destroyed from being serialized.
  46  *
  47  * <p>Keys that implement this interface return the string {@code RAW}
  48  * as their encoding format (see {@code getFormat}), and return the
  49  * raw key bytes as the result of a {@code getEncoded} method call. (The
  50  * {@code getFormat} and {@code getEncoded} methods are inherited
  51  * from the {@link java.security.Key} parent interface.)
  52  *
  53  * @author Jan Luehe
  54  *
  55  * @see SecretKeyFactory
  56  * @see Cipher
  57  * @since 1.4
  58  */
  59 
  60 public interface SecretKey extends
  61     java.security.Key, javax.security.auth.Destroyable {
  62 
  63     /**
  64      * The class fingerprint that is set to indicate serialization
  65      * compatibility since J2SE 1.4.
  66      */
  67     @SuppressWarnings("serial") // serialVersionUID in an interface is ineffectual
  68     static final long serialVersionUID = -4795878709595146952L;
  69 }