mirror of git://gcc.gnu.org/git/gcc.git
414 lines
13 KiB
Java
414 lines
13 KiB
Java
/* Mac.java -- The message authentication code interface.
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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.Security;
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import java.security.spec.AlgorithmParameterSpec;
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/**
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* This class implements a "message authentication code" (MAC), a method
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* to ensure the integrity of data transmitted between two parties who
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* share a common secret key.
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*
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* <p>The best way to describe a MAC is as a <i>keyed one-way hash
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* function</i>, which looks like:
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*
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* <blockquote><p><code>D = MAC(K, M)</code></blockquote>
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*
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* <p>where <code>K</code> is the key, <code>M</code> is the message,
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* and <code>D</code> is the resulting digest. One party will usually
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* send the concatenation <code>M || D</code> to the other party, who
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* will then verify <code>D</code> by computing <code>D'</code> in a
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* similar fashion. If <code>D == D'</code>, then the message is assumed
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* to be authentic.
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*
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* @author Casey Marshall (csm@gnu.org)
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*/
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public class Mac implements Cloneable
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{
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// Fields.
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// ------------------------------------------------------------------------
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private static final String SERVICE = "Mac";
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/** The underlying MAC implementation. */
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private MacSpi macSpi;
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/** The provider we got our implementation from. */
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private Provider provider;
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/** The name of the algorithm. */
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private String algorithm;
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/** Whether or not we've been initialized. */
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private boolean virgin;
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// Constructor.
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// ------------------------------------------------------------------------
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/**
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* Creates a new Mac instance.
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*
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* @param macSpi The underlying MAC implementation.
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* @param provider The provider of this implementation.
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* @param algorithm The name of this MAC algorithm.
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*/
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protected Mac(MacSpi macSpi, Provider provider, String algorithm)
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{
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this.macSpi = macSpi;
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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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// Class methods.
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// ------------------------------------------------------------------------
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/**
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* Get an instance of the named algorithm from the first provider with
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* an appropriate implementation.
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*
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* @param algorithm The name of the algorithm.
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* @return An appropriate Mac instance, if the specified algorithm
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* is implemented by a provider.
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* @throws java.security.NoSuchAlgorithmException If no implementation
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* of the named algorithm is installed.
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*/
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public static final Mac getInstance(String algorithm)
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throws NoSuchAlgorithmException
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{
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Provider[] provs = Security.getProviders();
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String msg = "";
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for (int i = 0; i < provs.length; i++)
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{
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try
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{
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return getInstance(algorithm, provs[i]);
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}
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catch (NoSuchAlgorithmException nsae)
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{
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msg = nsae.getMessage();
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}
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}
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throw new NoSuchAlgorithmException(msg);
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}
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/**
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* Get an instance of the named algorithm from the named provider.
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*
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* @param algorithm The name of the algorithm.
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* @param provider The name of the provider.
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* @return An appropriate Mac instance, if the specified algorithm is
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* implemented by the named provider.
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* @throws java.security.NoSuchAlgorithmException If the named provider
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* has no implementation of the algorithm.
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* @throws java.security.NoSuchProviderException If the named provider
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* does not exist.
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*/
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public static final Mac getInstance(String algorithm, String provider)
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throws NoSuchAlgorithmException, NoSuchProviderException
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{
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Provider p = Security.getProvider(provider);
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if (p == null)
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{
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throw new NoSuchProviderException(provider);
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}
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return getInstance(algorithm, p);
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}
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/**
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* Get an instance of the named algorithm from a provider.
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*
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* @param algorithm The name of the algorithm.
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* @param provider The provider.
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* @return An appropriate Mac instance, if the specified algorithm is
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* implemented by the provider.
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* @throws java.security.NoSuchAlgorithmException If the provider
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* has no implementation of the algorithm.
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*/
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public static final Mac getInstance(String algorithm, Provider provider)
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throws NoSuchAlgorithmException
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{
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try
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{
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return new Mac((MacSpi) Engine.getInstance(SERVICE, algorithm, provider),
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provider, algorithm);
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}
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catch (InvocationTargetException ite)
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{
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if (ite.getCause() == null)
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throw new NoSuchAlgorithmException(algorithm);
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if (ite.getCause() instanceof NoSuchAlgorithmException)
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throw (NoSuchAlgorithmException) ite.getCause();
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throw new NoSuchAlgorithmException(algorithm);
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}
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catch (ClassCastException cce)
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{
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throw new NoSuchAlgorithmException(algorithm);
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}
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}
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// Instance methods.
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// ------------------------------------------------------------------------
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/**
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* Finishes the computation of a MAC and returns the digest.
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*
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* <p>After this method succeeds, it may be used again as just after a
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* call to <code>init</code>, and can compute another MAC using the
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* same key and parameters.
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*
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* @return The message authentication code.
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* @throws java.lang.IllegalStateException If this instnace has not
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* been initialized.
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*/
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public final byte[] doFinal() 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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byte[] digest = macSpi.engineDoFinal();
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reset();
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return digest;
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}
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/**
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* Finishes the computation of a MAC with a final byte array (or
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* computes a MAC over those bytes only) and returns the digest.
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*
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* <p>After this method succeeds, it may be used again as just after a
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* call to <code>init</code>, and can compute another MAC using the
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* same key and parameters.
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*
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* @param input The bytes to add.
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* @return The message authentication code.
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* @throws java.lang.IllegalStateException If this instnace has not
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* been initialized.
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*/
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public final byte[] doFinal(byte[] input) throws IllegalStateException
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{
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update(input);
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byte[] digest = macSpi.engineDoFinal();
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reset();
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return digest;
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}
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/**
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* Finishes the computation of a MAC and places the result into the
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* given array.
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*
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* <p>After this method succeeds, it may be used again as just after a
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* call to <code>init</code>, and can compute another MAC using the
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* same key and parameters.
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*
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* @param output The destination for the result.
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* @param outOffset The index in the output array to start.
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* @return The message authentication code.
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* @throws java.lang.IllegalStateException If this instnace has not
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* been initialized.
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* @throws javax.crypto.ShortBufferException If <code>output</code> is
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* not large enough to hold the result.
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*/
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public final void doFinal(byte[] output, int outOffset)
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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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if (output.length - outOffset < getMacLength())
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{
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throw new ShortBufferException();
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}
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byte[] mac = macSpi.engineDoFinal();
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System.arraycopy(mac, 0, output, outOffset, getMacLength());
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reset();
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}
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/**
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* Returns the name of this MAC algorithm.
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*
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* @return The MAC 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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* Get the size of the MAC. This is the size of the array returned by
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* {@link #doFinal()} and {@link #doFinal(byte[])}, and the minimum
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* number of bytes that must be available in the byte array passed to
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* {@link #doFinal(byte[],int)}.
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*
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* @return The MAC length.
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*/
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public final int getMacLength()
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{
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return macSpi.engineGetMacLength();
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}
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/**
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* Get 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 MAC with a key and no parameters.
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*
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* @param key The key to initialize this instance with.
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* @throws java.security.InvalidKeyException If the key is
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* unacceptable.
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*/
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public final void init(Key key) throws InvalidKeyException
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{
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try
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{
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init(key, null);
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}
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catch (InvalidAlgorithmParameterException iape)
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{
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throw new IllegalArgumentException(algorithm + " needs parameters");
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}
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}
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/**
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* Initialize this MAC with a key and parameters.
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*
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* @param key The key to initialize this instance with.
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* @param params The algorithm-specific parameters.
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* @throws java.security.InvalidAlgorithmParameterException If the
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* algorithm parameters are unacceptable.
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* @throws java.security.InvalidKeyException If the key is
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* unacceptable.
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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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macSpi.engineInit(key, params);
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virgin = false; // w00t!
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}
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/**
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* Reset this instance. A call to this method returns this instance
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* back to the state it was in just after it was initialized.
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*/
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public final void reset()
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{
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macSpi.engineReset();
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}
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/**
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* Update the computation with a single byte.
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*
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* @param input The next byte.
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* @throws java.lang.IllegalStateException If this instance has not
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* been initialized.
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*/
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public final void update(byte input) 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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macSpi.engineUpdate(input);
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}
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/**
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* Update the computation with a byte array.
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*
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* @param input The next bytes.
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* @throws java.lang.IllegalStateException If this instance has not
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* been initialized.
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*/
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public final void update(byte[] input) throws IllegalStateException
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{
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update(input, 0, input.length);
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}
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/**
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* Update the computation with a portion of a byte array.
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*
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* @param input The next bytes.
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* @param offset The index in <code>input</code> to start.
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* @param length The number of bytes to update.
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* @throws java.lang.IllegalStateException If this instance has not
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* been initialized.
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*/
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public final void update(byte[] input, int offset, int length)
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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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macSpi.engineUpdate(input, offset, length);
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}
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/**
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* Clone this instance, if the underlying implementation supports it.
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*
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* @return A clone of this instance.
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* @throws java.lang.CloneNotSupportedException If the underlying
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* implementation is not cloneable.
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*/
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public final Object clone() throws CloneNotSupportedException
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{
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Mac result = new Mac((MacSpi) macSpi.clone(), provider, algorithm);
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result.virgin = virgin;
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return result;
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}
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}
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