/*
* @(#)KeyPairGenerator.java 1.56 06/10/10
*
* Copyright 1990-2006 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program 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.
*
* This program 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 at /legal/license.txt).
*
* 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 Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*
*/
package java.security;
import java.security.spec.AlgorithmParameterSpec;
/**
* 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.
*
* @author Benjamin Renaud
*
* @version 1.49, 02/02/00
*
* @see java.security.spec.AlgorithmParameterSpec
*/
public abstract class KeyPairGenerator extends KeyPairGeneratorSpi {
private String algorithm;
// The provider
private Provider provider;
/**
* Creates a KeyPairGenerator object for the specified algorithm.
*
* @param algorithm the standard string name of the algorithm.
* See Appendix A in the <a href=
* "../../../guide/security/CryptoSpec.html#AppA">
* Java Cryptography Architecture API Specification & Reference </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 Appendix A in the <a href=
* "../../../guide/security/CryptoSpec.html#AppA">
* Java Cryptography Architecture API Specification & Reference </a>
* for information about standard algorithm names.
*
* @return the standard string name of the algorithm.
*/
public String getAlgorithm() {
return this.algorithm;
}
/**
* Generates a KeyPairGenerator object that implements the specified digest
* algorithm. If the default provider package
* provides an implementation of the requested digest algorithm,
* an instance of KeyPairGenerator containing that implementation is
* returned.
* If the algorithm is not available in the default
* package, other packages are searched.
*
* @param algorithm the standard string name of the algorithm.
* See Appendix A in the <a href=
* "../../../guide/security/CryptoSpec.html#AppA">
* Java Cryptography Architecture API Specification & Reference </a>
* for information about standard algorithm names.
*
* @return the new KeyPairGenerator object.
*
* @exception NoSuchAlgorithmException if the algorithm is
* not available in the environment.
*/
public static KeyPairGenerator getInstance(String algorithm)
throws NoSuchAlgorithmException {
try {
Object[] objs = Security.getImpl(algorithm, "KeyPairGenerator",
(String)null);
if (objs[0] instanceof KeyPairGenerator) {
KeyPairGenerator keyPairGen = (KeyPairGenerator)objs[0];
keyPairGen.provider = (Provider)objs[1];
return keyPairGen;
} else {
KeyPairGenerator delegate =
new Delegate((KeyPairGeneratorSpi)objs[0], algorithm);
delegate.provider = (Provider)objs[1];
return delegate;
}
} catch(NoSuchProviderException e) {
throw new NoSuchAlgorithmException(algorithm + " not found");
}
}
/**
* Generates a KeyPairGenerator object implementing the specified
* algorithm, as supplied from the specified provider,
* if such an algorithm is available from the provider.
*
* @param algorithm the standard string name of the algorithm.
* See Appendix A in the <a href=
* "../../../guide/security/CryptoSpec.html#AppA">
* Java Cryptography Architecture API Specification & Reference </a>
* for information about standard algorithm names.
*
* @param provider the string name of the provider.
*
* @return the new KeyPairGenerator object.
*
* @exception NoSuchAlgorithmException if the algorithm is
* not available from the provider.
*
* @exception NoSuchProviderException if the provider is not
* available in the environment.
*
* @exception IllegalArgumentException if the provider name is null
* or empty.
*
* @see Provider
*/
public static KeyPairGenerator getInstance(String algorithm,
String provider)
throws NoSuchAlgorithmException, NoSuchProviderException
{
if (provider == null || provider.length() == 0)
throw new IllegalArgumentException("missing provider");
Object[] objs = Security.getImpl(algorithm, "KeyPairGenerator",
provider);
if (objs[0] instanceof KeyPairGenerator) {
KeyPairGenerator keyPairGen = (KeyPairGenerator)objs[0];
keyPairGen.provider = (Provider)objs[1];
return keyPairGen;
} else {
KeyPairGenerator delegate =
new Delegate((KeyPairGeneratorSpi)objs[0], algorithm);
delegate.provider = (Provider)objs[1];
return delegate;
}
}
/**
* Generates a KeyPairGenerator object implementing the specified
* algorithm, as supplied from the specified provider,
* if such an algorithm is available from the provider.
* Note: the <code>provider</code> doesn't have to be registered.
*
* @param algorithm the standard string name of the algorithm.
* See Appendix A in the <a href=
* "../../../guide/security/CryptoSpec.html#AppA">
* Java Cryptography Architecture API Specification & Reference </a>
* for information about standard algorithm names.
*
* @param provider the provider.
*
* @return the new KeyPairGenerator object.
*
* @exception NoSuchAlgorithmException if the algorithm is
* not available from the provider.
*
* @exception IllegalArgumentException if the <code>provider</code> is
* null.
*
* @see Provider
*
* @since 1.4
*/
public static KeyPairGenerator getInstance(String algorithm,
Provider provider)
throws NoSuchAlgorithmException
{
if (provider == null)
throw new IllegalArgumentException("missing provider");
Object[] objs = Security.getImpl(algorithm, "KeyPairGenerator",
provider);
if (objs[0] instanceof KeyPairGenerator) {
KeyPairGenerator keyPairGen = (KeyPairGenerator)objs[0];
keyPairGen.provider = (Provider)objs[1];
return keyPairGen;
} else {
KeyPairGenerator delegate =
new Delegate((KeyPairGeneratorSpi)objs[0], algorithm);
delegate.provider = (Provider)objs[1];
return delegate;
}
}
/**
* Returns the provider of this key pair generator object.
*
* @return the provider of this key pair generator object
*/
public final Provider getProvider() {
return this.provider;
}
/**
* 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, new SecureRandom());
}
/**
* 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.html#
* 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, new SecureRandom());
}
/**
* 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.html#
* 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
* the SPI object encapsulated.
*
* Note: All SPI methods from the original KeyPairGenerator class have been
* moved up the hierarchy into a new class (KeyPairGeneratorSpi), which has
* been interposed in the hierarchy between the API (KeyPairGenerator)
* and its original parent (Object).
*/
static class Delegate extends KeyPairGenerator {
// The provider implementation (delegate)
private KeyPairGeneratorSpi kpairGenSpi;
// constructor
public Delegate(KeyPairGeneratorSpi kpairGenSpi, String algorithm) {
super(algorithm);
this.kpairGenSpi = kpairGenSpi;
}
// engine method
public void initialize(int keysize, SecureRandom random) {
kpairGenSpi.initialize(keysize, random);
}
// engine method
public void initialize(AlgorithmParameterSpec params,
SecureRandom random)
throws InvalidAlgorithmParameterException {
kpairGenSpi.initialize(params, random);;
}
// engine method
public KeyPair generateKeyPair() {
return kpairGenSpi.generateKeyPair();
}
}
}
|