/* * Copyright (c) 1997, 2011, 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; import java.util.*; import java.security.spec.AlgorithmParameterSpec; import java.security.Provider.Service; import sun.security.jca.*;import sun.security.jca.GetInstance.Instance; /** * The KeyPairGenerator class is used to generate pairs of * public and private keys. Key pair generators are constructed using the * <code>getInstance</code> factory methods (static methods that * return instances of a given class). * * <p>A Key pair generator for a particular algorithm creates a public/private * key pair that can be used with this algorithm. It also associates * algorithm-specific parameters with each of the generated keys. * * <p>There are two ways to generate a key pair: in an algorithm-independent * manner, and in an algorithm-specific manner. * The only difference between the two is the initialization of the object: * * <ul> * <li><b>Algorithm-Independent Initialization</b> * <p>All key pair generators share the concepts of a keysize and a * source of randomness. The keysize is interpreted differently for different * algorithms (e.g., in the case of the <i>DSA</i> algorithm, the keysize * corresponds to the length of the modulus). * There is an * {@link #initialize(int, java.security.SecureRandom) initialize} * method in this KeyPairGenerator class that takes these two universally * shared types of arguments. There is also one that takes just a * <code>keysize</code> argument, and uses the <code>SecureRandom</code> * implementation of the highest-priority installed provider as the source * of randomness. (If none of the installed providers supply an implementation * of <code>SecureRandom</code>, a system-provided source of randomness is * used.) * * <p>Since no other parameters are specified when you call the above * algorithm-independent <code>initialize</code> methods, it is up to the * provider what to do about the algorithm-specific parameters (if any) to be * associated with each of the keys. * * <p>If the algorithm is the <i>DSA</i> algorithm, and the keysize (modulus * size) is 512, 768, or 1024, then the <i>Sun</i> provider uses a set of * precomputed values for the <code>p</code>, <code>q</code>, and * <code>g</code> parameters. If the modulus size is not one of the above * values, the <i>Sun</i> provider creates a new set of parameters. Other * providers might have precomputed parameter sets for more than just the * three modulus sizes mentioned above. Still others might not have a list of * precomputed parameters at all and instead always create new parameter sets. * <p> * * <li><b>Algorithm-Specific Initialization</b> * <p>For situations where a set of algorithm-specific parameters already * exists (e.g., so-called <i>community parameters</i> in DSA), there are two * {@link #initialize(java.security.spec.AlgorithmParameterSpec) * initialize} methods that have an <code>AlgorithmParameterSpec</code> * argument. One also has a <code>SecureRandom</code> argument, while the * the other uses the <code>SecureRandom</code> * implementation of the highest-priority installed provider as the source * of randomness. (If none of the installed providers supply an implementation * of <code>SecureRandom</code>, a system-provided source of randomness is * used.) * </ul> * * <p>In case the client does not explicitly initialize the KeyPairGenerator * (via a call to an <code>initialize</code> method), each provider must * supply (and document) a default initialization. * For example, the <i>Sun</i> provider uses a default modulus size (keysize) * of 1024 bits. * * <p>Note that this class is abstract and extends from * <code>KeyPairGeneratorSpi</code> for historical reasons. * Application developers should only take notice of the methods defined in * this <code>KeyPairGenerator</code> class; all the methods in * the superclass are intended for cryptographic service providers who wish to * supply their own implementations of key pair generators. * * <p> Every implementation of the Java platform is required to support the * following standard <code>KeyPairGenerator</code> algorithms and keysizes in * parentheses: * <ul> * <li><tt>DiffieHellman</tt> (1024)</li> * <li><tt>DSA</tt> (1024)</li> * <li><tt>RSA</tt> (1024, 2048)</li> * </ul> * These algorithms are described in the <a href= * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyPairGenerator"> * KeyPairGenerator section</a> of the * Java Cryptography Architecture Standard Algorithm Name Documentation. * Consult the release documentation for your implementation to see if any * other algorithms are supported. * * @author Benjamin Renaud * * @see java.security.spec.AlgorithmParameterSpec */ public abstract class KeyPairGenerator extends KeyPairGeneratorSpi {     private final String algorithm;     // The provider    Provider provider;     /**     * Creates a KeyPairGenerator object for the specified algorithm.     *     * @param algorithm the standard string name of the algorithm.     * See the KeyPairGenerator section in the <a href=     * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyPairGenerator">     * Java Cryptography Architecture Standard Algorithm Name Documentation</a>     * for information about standard algorithm names.     */    protected KeyPairGenerator(String algorithm) {        this.algorithm = algorithm;    }     /**     * Returns the standard name of the algorithm for this key pair generator.     * See the KeyPairGenerator section in the <a href=     * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyPairGenerator">     * Java Cryptography Architecture Standard Algorithm Name Documentation</a>     * for information about standard algorithm names.     *     * @return the standard string name of the algorithm.     */    public String getAlgorithm() {        return this.algorithm;    }     private static KeyPairGenerator getInstance(Instance instance,            String algorithm) {        KeyPairGenerator kpg;        if (instance.impl instanceof KeyPairGenerator) {            kpg = (KeyPairGenerator)instance.impl;        } else {            KeyPairGeneratorSpi spi = (KeyPairGeneratorSpi)instance.impl;            kpg = new Delegate(spi, algorithm);        }        kpg.provider = instance.provider;        return kpg;    }     /**     * Returns a KeyPairGenerator object that generates public/private     * key pairs for the specified algorithm.     *     * <p> This method traverses the list of registered security Providers,     * starting with the most preferred Provider.     * A new KeyPairGenerator object encapsulating the     * KeyPairGeneratorSpi implementation from the first     * Provider that supports the specified algorithm is returned.     *     * <p> Note that the list of registered providers may be retrieved via     * the {@link Security#getProviders() Security.getProviders()} method.     *     * @param algorithm the standard string name of the algorithm.     * See the KeyPairGenerator section in the <a href=     * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyPairGenerator">     * Java Cryptography Architecture Standard Algorithm Name Documentation</a>     * for information about standard algorithm names.     *     * @return the new KeyPairGenerator object.     *     * @exception NoSuchAlgorithmException if no Provider supports a     *          KeyPairGeneratorSpi implementation for the     *          specified algorithm.     *     * @see Provider     */    public static KeyPairGenerator getInstance(String algorithm)            throws NoSuchAlgorithmException {        List<Service> list =                GetInstance.getServices("KeyPairGenerator", algorithm);        Iterator<Service> t = list.iterator();        if (t.hasNext() == false) {            throw new NoSuchAlgorithmException                (algorithm + " KeyPairGenerator not available");        }        // find a working Spi or KeyPairGenerator subclass        NoSuchAlgorithmException failure = null;        do {            Service s = t.next();            try {                Instance instance =                    GetInstance.getInstance(s, KeyPairGeneratorSpi.class);                if (instance.impl instanceof KeyPairGenerator) {                    return getInstance(instance, algorithm);                } else {                    return new Delegate(instance, t, algorithm);                }            } catch (NoSuchAlgorithmException e) {                if (failure == null) {                    failure = e;                }            }        } while (t.hasNext());        throw failure;    }     /**     * Returns a KeyPairGenerator object that generates public/private     * key pairs for the specified algorithm.     *     * <p> A new KeyPairGenerator object encapsulating the     * KeyPairGeneratorSpi implementation from the specified provider     * is returned.  The specified provider must be registered     * in the security provider list.     *     * <p> Note that the list of registered providers may be retrieved via     * the {@link Security#getProviders() Security.getProviders()} method.     *     * @param algorithm the standard string name of the algorithm.     * See the KeyPairGenerator section in the <a href=     * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyPairGenerator">     * Java Cryptography Architecture Standard Algorithm Name Documentation</a>     * for information about standard algorithm names.     *     * @param provider the string name of the provider.     *     * @return the new KeyPairGenerator object.     *     * @exception NoSuchAlgorithmException if a KeyPairGeneratorSpi     *          implementation for the specified algorithm is not     *          available from the specified provider.     *     * @exception NoSuchProviderException if the specified provider is not     *          registered in the security provider list.     *     * @exception IllegalArgumentException if the provider name is null     *          or empty.     *     * @see Provider     */    public static KeyPairGenerator getInstance(String algorithm,            String provider)            throws NoSuchAlgorithmException, NoSuchProviderException {        Instance instance = GetInstance.getInstance("KeyPairGenerator",                KeyPairGeneratorSpi.class, algorithm, provider);        return getInstance(instance, algorithm);    }     /**     * Returns a KeyPairGenerator object that generates public/private     * key pairs for the specified algorithm.     *     * <p> A new KeyPairGenerator object encapsulating the     * KeyPairGeneratorSpi implementation from the specified Provider     * object is returned.  Note that the specified Provider object     * does not have to be registered in the provider list.     *     * @param algorithm the standard string name of the algorithm.     * See the KeyPairGenerator section in the <a href=     * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyPairGenerator">     * Java Cryptography Architecture Standard Algorithm Name Documentation</a>     * for information about standard algorithm names.     *     * @param provider the provider.     *     * @return the new KeyPairGenerator object.     *     * @exception NoSuchAlgorithmException if a KeyPairGeneratorSpi     *          implementation for the specified algorithm is not available     *          from the specified Provider object.     *     * @exception IllegalArgumentException if the specified provider is null.     *     * @see Provider     *     * @since 1.4     */    public static KeyPairGenerator getInstance(String algorithm,            Provider provider) throws NoSuchAlgorithmException {        Instance instance = GetInstance.getInstance("KeyPairGenerator",                KeyPairGeneratorSpi.class, algorithm, provider);        return getInstance(instance, algorithm);    }     /**     * Returns the provider of this key pair generator object.     *     * @return the provider of this key pair generator object     */    public final Provider getProvider() {        disableFailover();        return this.provider;    }     void disableFailover() {        // empty, overridden in Delegate    }     /**     * Initializes the key pair generator for a certain keysize using     * a default parameter set and the <code>SecureRandom</code>     * implementation of the highest-priority installed provider as the source     * of randomness.     * (If none of the installed providers supply an implementation of     * <code>SecureRandom</code>, a system-provided source of randomness is     * used.)     *     * @param keysize the keysize. This is an     * algorithm-specific metric, such as modulus length, specified in     * number of bits.     *     * @exception InvalidParameterException if the <code>keysize</code> is not     * supported by this KeyPairGenerator object.     */    public void initialize(int keysize) {        initialize(keysize, JCAUtil.getSecureRandom());    }     /**     * Initializes the key pair generator for a certain keysize with     * the given source of randomness (and a default parameter set).     *     * @param keysize the keysize. This is an     * algorithm-specific metric, such as modulus length, specified in     * number of bits.     * @param random the source of randomness.     *     * @exception InvalidParameterException if the <code>keysize</code> is not     * supported by this KeyPairGenerator object.     *     * @since 1.2     */    public void initialize(int keysize, SecureRandom random) {        // This does nothing, because either        // 1. the implementation object returned by getInstance() is an        //    instance of KeyPairGenerator which has its own        //    initialize(keysize, random) method, so the application would        //    be calling that method directly, or        // 2. the implementation returned by getInstance() is an instance        //    of Delegate, in which case initialize(keysize, random) is        //    overridden to call the corresponding SPI method.        // (This is a special case, because the API and SPI method have the        // same name.)    }     /**     * Initializes the key pair generator using the specified parameter     * set and the <code>SecureRandom</code>     * implementation of the highest-priority installed provider as the source     * of randomness.     * (If none of the installed providers supply an implementation of     * <code>SecureRandom</code>, a system-provided source of randomness is     * used.).     *     * <p>This concrete method has been added to this previously-defined     * abstract class.     * This method calls the KeyPairGeneratorSpi     * {@link KeyPairGeneratorSpi#initialize(     * java.security.spec.AlgorithmParameterSpec,     * java.security.SecureRandom) initialize} method,     * passing it <code>params</code> and a source of randomness (obtained     * from the highest-priority installed provider or system-provided if none     * of the installed providers supply one).     * That <code>initialize</code> method always throws an     * UnsupportedOperationException if it is not overridden by the provider.     *     * @param params the parameter set used to generate the keys.     *     * @exception InvalidAlgorithmParameterException if the given parameters     * are inappropriate for this key pair generator.     *     * @since 1.2     */    public void initialize(AlgorithmParameterSpec params)            throws InvalidAlgorithmParameterException {        initialize(params, JCAUtil.getSecureRandom());    }     /**     * Initializes the key pair generator with the given parameter     * set and source of randomness.     *     * <p>This concrete method has been added to this previously-defined     * abstract class.     * This method calls the KeyPairGeneratorSpi {@link     * KeyPairGeneratorSpi#initialize(     * java.security.spec.AlgorithmParameterSpec,     * java.security.SecureRandom) initialize} method,     * passing it <code>params</code> and <code>random</code>.     * That <code>initialize</code>     * method always throws an     * UnsupportedOperationException if it is not overridden by the provider.     *     * @param params the parameter set used to generate the keys.     * @param random the source of randomness.     *     * @exception InvalidAlgorithmParameterException if the given parameters     * are inappropriate for this key pair generator.     *     * @since 1.2     */    public void initialize(AlgorithmParameterSpec params,                           SecureRandom random)        throws InvalidAlgorithmParameterException    {        // This does nothing, because either        // 1. the implementation object returned by getInstance() is an        //    instance of KeyPairGenerator which has its own        //    initialize(params, random) method, so the application would        //    be calling that method directly, or        // 2. the implementation returned by getInstance() is an instance        //    of Delegate, in which case initialize(params, random) is        //    overridden to call the corresponding SPI method.        // (This is a special case, because the API and SPI method have the        // same name.)    }     /**     * Generates a key pair.     *     * <p>If this KeyPairGenerator has not been initialized explicitly,     * provider-specific defaults will be used for the size and other     * (algorithm-specific) values of the generated keys.     *     * <p>This will generate a new key pair every time it is called.     *     * <p>This method is functionally equivalent to     * {@link #generateKeyPair() generateKeyPair}.     *     * @return the generated key pair     *     * @since 1.2     */    public final KeyPair genKeyPair() {        return generateKeyPair();    }     /**     * Generates a key pair.     *     * <p>If this KeyPairGenerator has not been initialized explicitly,     * provider-specific defaults will be used for the size and other     * (algorithm-specific) values of the generated keys.     *     * <p>This will generate a new key pair every time it is called.     *     * <p>This method is functionally equivalent to     * {@link #genKeyPair() genKeyPair}.     *     * @return the generated key pair     */    public KeyPair generateKeyPair() {        // This does nothing (except returning null), because either:        //        // 1. the implementation object returned by getInstance() is an        //    instance of KeyPairGenerator which has its own implementation        //    of generateKeyPair (overriding this one), so the application        //    would be calling that method directly, or        //        // 2. the implementation returned by getInstance() is an instance        //    of Delegate, in which case generateKeyPair is        //    overridden to invoke the corresponding SPI method.        //        // (This is a special case, because in JDK 1.1.x the generateKeyPair        // method was used both as an API and a SPI method.)        return null;    }      /*     * The following class allows providers to extend from KeyPairGeneratorSpi     * rather than from KeyPairGenerator. It represents a KeyPairGenerator     * with an encapsulated, provider-supplied SPI object (of type     * KeyPairGeneratorSpi).     * If the provider implementation is an instance of KeyPairGeneratorSpi,     * the getInstance() methods above return an instance of this class, with

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