379 lines
13 KiB
Java
379 lines
13 KiB
Java
/* KeyAgreement.java -- Engine for key agreement methods.
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Copyright (C) 2004 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package javax.crypto;
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import gnu.java.security.Engine;
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import java.lang.reflect.InvocationTargetException;
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import java.security.InvalidAlgorithmParameterException;
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import java.security.InvalidKeyException;
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import java.security.Key;
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import java.security.NoSuchAlgorithmException;
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import java.security.NoSuchProviderException;
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import java.security.Provider;
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import java.security.SecureRandom;
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import java.security.Security;
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import java.security.spec.AlgorithmParameterSpec;
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/**
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* Key agreement is a method in which two or more parties may agree on a
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* secret key for symmetric cryptography or message authentication
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* without transmitting any secrets in the clear. Key agreement
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* algorithms typically use a public/private <i>key pair</i>, and the
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* public key (along with some additional information) is sent across
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* untrusted networks.
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*
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* <p>The most common form of key agreement used today is the
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* <i>Diffie-Hellman key exchange algorithm</i>, described in <a
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* href="http://www.rsasecurity.com/rsalabs/pkcs/pkcs-3/">PKCS #3 -
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* Diffie Hellman Key Agreement Standard</a>.
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*
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* @author Casey Marshall (csm@gnu.org)
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* @since 1.4
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* @see KeyGenerator
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* @see SecretKey
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*/
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public class KeyAgreement
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{
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// Fields.
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// ------------------------------------------------------------------------
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private static final String SERVICE = "KeyAgreement";
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/** The underlying key agreement implementation. */
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private KeyAgreementSpi kaSpi;
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/** The provider of this implementation. */
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private Provider provider;
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/** The name of this instance's algorithm. */
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private String algorithm;
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/** Singnals whether or not this instance has been initialized. */
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private boolean virgin;
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// Constructor.
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// ------------------------------------------------------------------------
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protected KeyAgreement(KeyAgreementSpi kaSpi, Provider provider,
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String algorithm)
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{
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this.kaSpi = kaSpi;
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this.provider = provider;
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this.algorithm = algorithm;
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virgin = true;
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}
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/**
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* Get an implementation of an algorithm from the first provider that
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* implements it.
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*
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* @param algorithm The name of the algorithm to get.
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* @return The proper KeyAgreement instacne, if found.
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* @throws NoSuchAlgorithmException If the specified algorithm is not
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* implemented by any installed provider.
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* @throws IllegalArgumentException if <code>algorithm</code> is
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* <code>null</code> or is an empty string.
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*/
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public static final KeyAgreement getInstance(String algorithm)
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throws NoSuchAlgorithmException
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{
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Provider[] p = Security.getProviders();
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NoSuchAlgorithmException lastException = null;
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for (int i = 0; i < p.length; i++)
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try
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{
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return getInstance(algorithm, p[i]);
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}
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catch (NoSuchAlgorithmException x)
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{
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lastException = x;
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}
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if (lastException != null)
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throw lastException;
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throw new NoSuchAlgorithmException(algorithm);
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}
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/**
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* Return an implementation of an algorithm from a named provider.
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*
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* @param algorithm The name of the algorithm to create.
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* @param provider The name of the provider from which to get the
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* implementation.
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* @return The proper KeyAgreement instance, if found.
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* @throws NoSuchAlgorithmException If the named provider does not implement
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* the algorithm.
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* @throws NoSuchProviderException If the named provider does not exist.
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* @throws IllegalArgumentException if either <code>algorithm</code> or
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* <code>provider</code> is <code>null</code>, or if
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* <code>algorithm</code> is an empty string.
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*/
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public static final KeyAgreement getInstance(String algorithm, String provider)
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throws NoSuchAlgorithmException, NoSuchProviderException
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{
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if (provider == null)
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throw new IllegalArgumentException("provider MUST NOT be null");
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Provider p = Security.getProvider(provider);
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if (p == null)
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throw new NoSuchProviderException(provider);
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return getInstance(algorithm, p);
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}
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/**
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* Return an implementation of an algorithm from a specific provider.
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*
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* @param algorithm The name of the algorithm to get.
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* @param provider The provider from which to get the implementation.
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* @return The proper KeyAgreement instance, if found.
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* @throws NoSuchAlgorithmException If this provider does not implement the
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* algorithm.
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* @throws IllegalArgumentException if either <code>algorithm</code> or
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* <code>provider</code> is <code>null</code>, or if
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* <code>algorithm</code> is an empty string.
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*/
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public static final KeyAgreement getInstance(String algorithm,
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Provider provider)
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throws NoSuchAlgorithmException
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{
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StringBuilder sb = new StringBuilder("KeyAgreement algorithm [")
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.append(algorithm).append("] from provider[")
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.append(provider).append("] could not be created");
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Throwable cause;
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try
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{
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Object spi = Engine.getInstance(SERVICE, algorithm, provider);
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return new KeyAgreement((KeyAgreementSpi) spi, provider, algorithm);
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}
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catch (InvocationTargetException x)
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{
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cause = x.getCause();
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if (cause instanceof NoSuchAlgorithmException)
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throw (NoSuchAlgorithmException) cause;
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if (cause == null)
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cause = x;
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}
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catch (ClassCastException x)
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{
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cause = x;
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}
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NoSuchAlgorithmException x = new NoSuchAlgorithmException(sb.toString());
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x.initCause(cause);
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throw x;
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}
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/**
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* Do a phase in the key agreement. The number of times this method is
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* called depends upon the algorithm and the number of parties
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* involved, but must be called at least once with the
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* <code>lastPhase</code> flag set to <code>true</code>.
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*
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* @param key The key for this phase.
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* @param lastPhase Should be <code>true</code> if this will be the
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* last phase before generating the shared secret.
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* @return The intermediate result, or <code>null</code> if there is
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* no intermediate result.
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* @throws java.lang.IllegalStateException If this instance has not
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* been initialized.
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* @throws java.security.InvalidKeyException If the key is
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* inappropriate for this algorithm.
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*/
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public final Key doPhase(Key key, boolean lastPhase)
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throws IllegalStateException, InvalidKeyException
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{
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if (virgin)
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{
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throw new IllegalStateException("not initialized");
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}
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return kaSpi.engineDoPhase(key, lastPhase);
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}
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/**
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* Generate the shared secret in a new byte array.
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*
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* @return The shared secret.
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* @throws java.lang.IllegalStateException If this instnace has not
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* been initialized, or if not enough calls to
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* <code>doPhase</code> have been made.
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*/
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public final byte[] generateSecret() throws IllegalStateException
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{
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if (virgin)
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{
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throw new IllegalStateException("not initialized");
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}
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return kaSpi.engineGenerateSecret();
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}
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/**
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* Generate the shared secret and store it into the supplied array.
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*
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* @param sharedSecret The array in which to store the secret.
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* @param offset The index in <code>sharedSecret</code> to start
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* storing data.
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* @return The length of the shared secret, in bytes.
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* @throws java.lang.IllegalStateException If this instnace has not
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* been initialized, or if not enough calls to
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* <code>doPhase</code> have been made.
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* @throws javax.crypto.ShortBufferException If the supplied array is
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* not large enough to store the result.
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*/
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public final int generateSecret(byte[] sharedSecret, int offset)
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throws IllegalStateException, ShortBufferException
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{
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if (virgin)
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{
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throw new IllegalStateException("not initialized");
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}
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return kaSpi.engineGenerateSecret(sharedSecret, offset);
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}
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/**
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* Generate the shared secret and return it as an appropriate {@link
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* SecretKey}.
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*
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* @param algorithm The secret key's algorithm.
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* @return The shared secret as a secret key.
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* @throws java.lang.IllegalStateException If this instnace has not
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* been initialized, or if not enough calls to
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* <code>doPhase</code> have been made.
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* @throws java.security.InvalidKeyException If the shared secret
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* cannot be used to make a {@link SecretKey}.
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* @throws java.security.NoSuchAlgorithmException If the specified
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* algorithm does not exist.
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*/
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public final SecretKey generateSecret(String algorithm)
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throws IllegalStateException, InvalidKeyException, NoSuchAlgorithmException
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{
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if (virgin)
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{
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throw new IllegalStateException("not initialized");
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}
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return kaSpi.engineGenerateSecret(algorithm);
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}
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/**
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* Return the name of this key-agreement algorithm.
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*
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* @return The algorithm name.
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*/
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public final String getAlgorithm()
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{
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return algorithm;
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}
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/**
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* Return the provider of the underlying implementation.
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*
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* @return The provider.
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*/
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public final Provider getProvider()
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{
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return provider;
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}
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/**
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* Initialize this key agreement with a key. This method will use the
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* highest-priority {@link java.security.SecureRandom} as its source
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* of randomness.
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*
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* @param key The key, usually the user's private key.
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* @throws java.security.InvalidKeyException If the supplied key is
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* not appropriate.
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*/
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public final void init(Key key) throws InvalidKeyException
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{
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init(key, new SecureRandom());
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}
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/**
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* Initialize this key agreement with a key and a source of
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* randomness.
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*
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* @param key The key, usually the user's private key.
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* @param random The source of randomness.
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* @throws java.security.InvalidKeyException If the supplied key is
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* not appropriate.
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*/
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public final void init(Key key, SecureRandom random)
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throws InvalidKeyException
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{
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kaSpi.engineInit(key, random);
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virgin = false; // w00t!
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}
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/**
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* Initialize this key agreement with a key and parameters. This
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* method will use the highest-priority {@link
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* java.security.SecureRandom} as its source of randomness.
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*
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* @param key The key, usually the user's private key.
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* @param params The algorithm parameters.
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* @throws java.security.InvalidAlgorithmParameterException If the
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* supplied parameters are not appropriate.
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* @throws java.security.InvalidKeyException If the supplied key is
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* not appropriate.
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*/
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public final void init(Key key, AlgorithmParameterSpec params)
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throws InvalidAlgorithmParameterException, InvalidKeyException
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{
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init(key, params, new SecureRandom());
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}
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/**
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* Initialize this key agreement with a key, parameters, and source of
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* randomness.
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*
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* @param key The key, usually the user's private key.
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* @param params The algorithm parameters.
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* @param random The source of randomness.
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* @throws java.security.InvalidAlgorithmParameterException If the
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* supplied parameters are not appropriate.
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* @throws java.security.InvalidKeyException If the supplied key is
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* not appropriate.
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*/
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public final void init(Key key, AlgorithmParameterSpec params,
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SecureRandom random)
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throws InvalidAlgorithmParameterException, InvalidKeyException
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{
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kaSpi.engineInit(key, params, random);
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virgin = false; // w00t!
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}
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}
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