1 /*
   2  * Copyright (c) 1997, 2019, 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
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   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
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  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 java.security;
  27 
  28 import java.security.spec.AlgorithmParameterSpec;
  29 
  30 /**
  31  * <p> This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)
  32  * for the {@code KeyPairGenerator} class, which is used to generate
  33  * pairs of public and private keys.
  34  *
  35  * <p> All the abstract methods in this class must be implemented by each
  36  * cryptographic service provider who wishes to supply the implementation
  37  * of a key pair generator for a particular algorithm.
  38  *
  39  * <p> In case the client does not explicitly initialize the KeyPairGenerator
  40  * (via a call to an {@code initialize} method), each provider must
  41  * supply (and document) a default initialization.
  42  * See the Keysize Restriction sections of the
  43  * {@extLink security_guide_jdk_providers JDK Providers}
  44  * document for information on the KeyPairGenerator defaults used by
  45  * JDK providers.
  46  * However, note that defaults may vary across different providers.
  47  * Additionally, the default value for a provider may change in a future
  48  * version. Therefore, it is recommended to explicitly initialize the
  49  * KeyPairGenerator instead of relying on provider-specific defaults.
  50  *
  51  * @author Benjamin Renaud
  52  * @since 1.2
  53  *
  54  *
  55  * @see KeyPairGenerator
  56  * @see java.security.spec.AlgorithmParameterSpec
  57  */
  58 
  59 public abstract class KeyPairGeneratorSpi {
  60 
  61     /**
  62      * Initializes the key pair generator for a certain keysize, using
  63      * the default parameter set.
  64      *
  65      * @param keysize the keysize. This is an
  66      * algorithm-specific metric, such as modulus length, specified in
  67      * number of bits.
  68      *
  69      * @param random the source of randomness for this generator.
  70      *
  71      * @throws    InvalidParameterException if the {@code keysize} is not
  72      * supported by this KeyPairGeneratorSpi object.
  73      */
  74     public abstract void initialize(int keysize, SecureRandom random);
  75 
  76     /**
  77      * Initializes the key pair generator using the specified parameter
  78      * set and user-provided source of randomness.
  79      *
  80      * <p>This concrete method has been added to this previously-defined
  81      * abstract class. (For backwards compatibility, it cannot be abstract.)
  82      * It may be overridden by a provider to initialize the key pair
  83      * generator. Such an override
  84      * is expected to throw an InvalidAlgorithmParameterException if
  85      * a parameter is inappropriate for this key pair generator.
  86      * If this method is not overridden, it always throws an
  87      * UnsupportedOperationException.
  88      *
  89      * @param params the parameter set used to generate the keys.
  90      *
  91      * @param random the source of randomness for this generator.
  92      *
  93      * @throws    InvalidAlgorithmParameterException if the given parameters
  94      * are inappropriate for this key pair generator.
  95      *
  96      * @since 1.2
  97      */
  98     public void initialize(AlgorithmParameterSpec params,
  99                            SecureRandom random)
 100         throws InvalidAlgorithmParameterException {
 101             throw new UnsupportedOperationException();
 102     }
 103 
 104     /**
 105      * Generates a key pair. Unless an initialization method is called
 106      * using a KeyPairGenerator interface, algorithm-specific defaults
 107      * will be used. This will generate a new key pair every time it
 108      * is called.
 109      *
 110      * @return the newly generated {@code KeyPair}
 111      */
 112     public abstract KeyPair generateKeyPair();
 113 }