/* KeyPairGenerator.java --- Key Pair Generator Class Copyright (C) 1999, 2002, 2003 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath 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 for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version. */ package java.security; import java.security.spec.AlgorithmParameterSpec; import gnu.java.security.Engine; /** *
The KeyPairGenerator
class is used to generate pairs of
* public and private keys. Key pair generators are constructed using the
* getInstance()
factory methods (static methods that return
* instances of a given class).
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.
* *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:
* *initialize()
method in this KeyPairGenerator
* class that takes these two universally shared types of arguments. There
* is also one that takes just a keysize argument, and uses the
* {@link SecureRandom} implementation of the highest-priority installed
* provider as the source of randomness. (If none of the installed
* providers supply an implementation of {@link SecureRandom}, a
* system-provided source of randomness is used.)512
, 768
, or 1024
,
* then the GNU provider uses a set of precomputed values for the
* p
, q
, and g
parameters. If the
* modulus size is not one of the above values, the GNU
* 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.In case the client does not explicitly initialize the
* KeyPairGenerator
(via a call to an initialize method), each
* provider must supply (and document) a default initialization. For example,
* the GNU provider uses a default modulus size (keysize) of
* 1024
bits.
Note that this class is abstract and extends from {@link
* KeyPairGeneratorSpi} for historical reasons. Application developers should
* only take notice of the methods defined in this KeyPairGenerator
* class; all the methods in the superclass are intended for cryptographic
* service providers who wish to supply their own implementations of key pair
* generators.
KeyPairGenerator
object for the specified
* algorithm.
*
* @param algorithm the standard string name of the algorithm.
* See Appendix A in the Java Cryptography Architecture API
* Specification & Reference for information about standard
* algorithm names.
*/
protected KeyPairGenerator(String algorithm)
{
this.algorithm = algorithm;
this.provider = null;
}
/**
* Returns the standard name of the algorithm for this key pair generator.
* See Appendix A in the Java Cryptography Architecture API Specification
* & Reference for information about standard algorithm names.
*
* @return the standard string name of the algorithm.
*/
public String getAlgorithm()
{
return 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 Java Cryptography Architecture API Specification & Reference for
* information about standard algorithm names.
* @return the new KeyPairGenerator
object.
* @throws NoSuchAlgorithmException if the algorithm is not available in the
* environment.
*/
public static KeyPairGenerator getInstance(String algorithm)
throws NoSuchAlgorithmException
{
Provider[] p = Security.getProviders();
for (int i = 0; i < p.length; i++)
{
try
{
return getInstance(algorithm, p[i]);
}
catch (NoSuchAlgorithmException ignored) {}
}
throw new NoSuchAlgorithmException(algorithm);
}
/**
* 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 Java Cryptography Architecture API Specification
* & Reference for information about standard algorithm names.
* @param provider the string name of the provider.
* @return the new KeyPairGenerator
object.
* @throws NoSuchAlgorithmException if the algorithm is not available
* from the provider.
* @throws NoSuchProviderException if the provider is not available in the
* environment.
* @throws IllegalArgumentException if the provider name is null
* or empty.
* @see Provider
*/
public static KeyPairGenerator getInstance(String algorithm, String provider)
throws NoSuchAlgorithmException, NoSuchProviderException
{
Provider p = Security.getProvider(provider);
if (p == null)
throw new NoSuchProviderException(provider);
return getInstance(algorithm, p);
}
/**
* 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 provider doesn't have to be
* registered.
*
* @param algorithm the standard string name of the algorithm. See Appendix A
* in the Java Cryptography Architecture API Specification & Reference for
* information about standard algorithm names.
* @param provider the provider.
* @return the new KeyPairGenerator
object.
* @throws NoSuchAlgorithmException if the algorithm
is not
* available from the provider
.
* @throws IllegalArgumentException if the provider
is
* null
.
* @since 1.4
* @see Provider
*/
public static KeyPairGenerator getInstance(String algorithm,
Provider provider)
throws NoSuchAlgorithmException
{
if (provider == null)
throw new IllegalArgumentException("Illegal provider");
Object o = null;
try
{
o = Engine.getInstance(KEY_PAIR_GENERATOR, algorithm, provider);
}
catch (java.lang.reflect.InvocationTargetException ite)
{
throw new NoSuchAlgorithmException(algorithm);
}
KeyPairGenerator result = null;
if (o instanceof KeyPairGeneratorSpi)
{
result = new DummyKeyPairGenerator((KeyPairGeneratorSpi) o, algorithm);
}
else if (o instanceof KeyPairGenerator)
{
result = (KeyPairGenerator) o;
result.algorithm = algorithm;
}
result.provider = provider;
return result;
}
/**
* Returns the provider of this key pair generator object.
*
* @return the provider of this key pair generator object.
*/
public final Provider getProvider()
{
return provider;
}
/**
* Initializes the key pair generator for a certain keysize using a default
* parameter set and the {@link SecureRandom} implementation of the
* highest-priority installed provider as the source of randomness. (If none
* of the installed providers supply an implementation of {@link SecureRandom},
* 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.
* @throws InvalidParameterException if the keysize 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.
* @throws InvalidParameterException if the keysize
is not
* supported by this KeyPairGenerator
object.
* @since 1.2
*/
public void initialize(int keysize, SecureRandom random)
{
initialize(keysize, random);
}
/**
* Initializes the key pair generator using the specified parameter set and * the {@link SecureRandom} implementation of the highest-priority installed * provider as the source of randomness. (If none of the installed providers * supply an implementation of {@link SecureRandom}, a system-provided source * of randomness is used.)
* *This concrete method has been added to this previously-defined abstract
* class. This method calls the
* {@link KeyPairGeneratorSpi#initialize(AlgorithmParameterSpec, SecureRandom)}
* initialize method, passing it params
and a source of
* randomness (obtained from the highest-priority installed provider or
* system-provided if none of the installed providers supply one). That
* initialize method always throws an {@link UnsupportedOperationException}
* if it is not overridden by the provider.
Initializes the key pair generator with the given parameter set and * source of randomness.
* *This concrete method has been added to this previously-defined abstract
* class. This method calls the
* {@link KeyPairGeneratorSpi#initialize(AlgorithmParameterSpec, SecureRandom)}
* initialize method, passing it params
and random
.
* That initialize method always throws an {@link UnsupportedOperationException}
* if it is not overridden by the provider.
Generates a key pair.
* *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.
This will generate a new key pair every time it is called.
* *This method is functionally equivalent to {@link #generateKeyPair()}.
* * @return the generated key pair. * @since 1.2 */ public final KeyPair genKeyPair() { try { return getInstance("DSA", "GNU").generateKeyPair(); } catch (Exception e) { System.err.println("genKeyPair failed: " + e); e.printStackTrace(); return null; } } /** *Generates a key pair.
* *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.
This will generate a new key pair every time it is called.
* *This method is functionally equivalent to {@link #genKeyPair()}.
* * @return the generated key pair. */ public KeyPair generateKeyPair() { return genKeyPair(); } }