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jlechner |
/* MessageDigest.java --- The message digest interface.
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Copyright (C) 1999, 2002, 2003 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 java.security;
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import gnu.java.security.Engine;
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/**
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* <p>This <code>MessageDigest</code> class provides applications the
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* functionality of a message digest algorithm, such as <i>MD5</i> or <i>SHA</i>.
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* Message digests are secure one-way hash functions that take arbitrary-sized
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* data and output a fixed-length hash value.</p>
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*
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* <p>A <code>MessageDigest</code> object starts out initialized. The data is
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* processed through it using the <code>update()</code> methods. At any point
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* <code>reset()</code> can be called to reset the digest. Once all the data to
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* be updated has been updated, one of the <code>digest()</code> methods should
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* be called to complete the hash computation.</p>
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*
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* <p>The <code>digest()</code> method can be called <b>once</b> for a given
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* number of updates. After <code>digest()</code> has been called, the
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* <code>MessageDigest</code> object is <b>reset</b> to its initialized state.
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* </p>
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*
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* <p>Implementations are free to implement the {@link Cloneable} interface.
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* Client applications can test cloneability by attempting cloning and catching
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* the {@link CloneNotSupportedException}:
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*
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* <pre>
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* MessageDigest md = MessageDigest.getInstance("SHA");
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* try
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* {
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* md.update(toChapter1);
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* MessageDigest tc1 = md.clone();
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* byte[] toChapter1Digest = tc1.digest();
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* md.update(toChapter2);
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* // ...
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* }
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* catch (CloneNotSupportedException x)
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* {
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* throw new DigestException("couldn't make digest of partial content");
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* }
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* </pre>
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*
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* <p>Note that if a given implementation is not cloneable, it is still possible
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* to compute intermediate digests by instantiating several instances, if the
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* number of digests is known in advance.</p>
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*
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* <p>Note that this class is abstract and extends from {@link MessageDigestSpi}
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* for historical reasons. Application developers should only take notice of the
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* methods defined in this <code>MessageDigest</code> class; all the methods in
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* the superclass are intended for cryptographic service providers who wish to
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* supply their own implementations of message digest algorithms.</p>
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*
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* @see MessageDigestSpi
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* @see Provider
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* @since JDK 1.1
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*/
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public abstract class MessageDigest extends MessageDigestSpi
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{
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/** The service name for message digests. */
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private static final String MESSAGE_DIGEST = "MessageDigest";
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private String algorithm;
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Provider provider;
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private byte[] lastDigest;
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/**
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* Creates a message digest with the specified algorithm name.
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*
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* @param algorithm the standard name of the digest algorithm.
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* See Appendix A in the Java Cryptography Architecture API
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* Specification & Reference for information about standard
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* algorithm names.
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*/
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protected MessageDigest(String algorithm)
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{
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this.algorithm = algorithm;
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provider = null;
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}
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/**
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* Generates a <code>MessageDigest</code> object that implements the specified
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* digest algorithm. If the default provider package provides an
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* implementation of the requested digest algorithm, an instance of
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* <code>MessageDigest</code> containing that implementation is returned. If
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* the algorithm is not available in the default package, other packages are
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* searched.
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*
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* @param algorithm the name of the algorithm requested. See Appendix A in the
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* Java Cryptography Architecture API Specification & Reference for
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* information about standard algorithm names.
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* @return a Message Digest object implementing the specified algorithm.
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* @throws NoSuchAlgorithmException if the algorithm is not available in the
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* caller's environment.
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*/
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public static MessageDigest 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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for (int i = 0; i < p.length; i++)
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{
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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 ignored)
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{
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// Ignore.
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}
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}
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throw new NoSuchAlgorithmException(algorithm);
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}
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/**
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* Generates a <code>MessageDigest</code> object implementing the specified
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* algorithm, as supplied from the specified provider, if such an algorithm is
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* available from the provider.
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*
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* @param algorithm the name of the algorithm requested. See Appendix A in the
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* Java Cryptography Architecture API Specification & Reference for
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* information about standard algorithm names.
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* @param provider the name of the provider.
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* @return a Message Digest object implementing the specified algorithm.
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* @throws NoSuchAlgorithmException if the algorithm is not available in the
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* package supplied by the requested provider.
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* @throws NoSuchProviderException if the provider is not available in the
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* environment.
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* @throws IllegalArgumentException if the provider name is null or empty.
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* @see Provider
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*/
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public static MessageDigest getInstance(String algorithm, String provider)
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throws NoSuchAlgorithmException, NoSuchProviderException
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{
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if (provider == null || provider.length() == 0)
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throw new IllegalArgumentException("Illegal provider");
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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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* Generates a <code>MessageDigest</code> object implementing the specified
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* algorithm, as supplied from the specified provider, if such an algorithm
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* is available from the provider. Note: the provider doesn't have to be
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* registered.
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*
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* @param algorithm the name of the algorithm requested. See Appendix A in
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* the Java Cryptography Architecture API Specification & Reference for
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* information about standard algorithm names.
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* @param provider the provider.
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* @return a Message Digest object implementing the specified algorithm.
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* @throws NoSuchAlgorithmException if the <code>algorithm</code> is not
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* available in the package supplied by the requested <code>provider</code>.
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* @throws IllegalArgumentException if the <code>provider</code> is
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* <code>null</code>.
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* @since 1.4
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* @see Provider
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*/
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public static MessageDigest getInstance(String algorithm, Provider provider)
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throws NoSuchAlgorithmException
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{
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if (provider == null)
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throw new IllegalArgumentException("Illegal provider");
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MessageDigest result = null;
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Object o = null;
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try
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{
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o = Engine.getInstance(MESSAGE_DIGEST, algorithm, provider);
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}
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catch (java.lang.reflect.InvocationTargetException ite)
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{
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throw new NoSuchAlgorithmException(algorithm);
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}
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if (o instanceof MessageDigestSpi)
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{
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result = new DummyMessageDigest((MessageDigestSpi) o, algorithm);
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}
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else if (o instanceof MessageDigest)
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{
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result = (MessageDigest) o;
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result.algorithm = algorithm;
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}
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else
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{
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throw new NoSuchAlgorithmException(algorithm);
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}
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result.provider = provider;
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return result;
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}
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/**
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* Returns the provider of this message digest object.
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*
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* @return the provider of this message digest object.
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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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* Updates the digest using the specified byte.
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*
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* @param input the byte with which to update the digest.
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*/
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public void update(byte input)
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{
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engineUpdate(input);
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}
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/**
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* Updates the digest using the specified array of bytes, starting at the
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* specified offset.
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*
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* @param input the array of bytes.
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* @param offset the offset to start from in the array of bytes.
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* @param len the number of bytes to use, starting at offset.
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*/
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public void update(byte[] input, int offset, int len)
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{
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engineUpdate(input, offset, len);
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}
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/**
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* Updates the digest using the specified array of bytes.
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*
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* @param input the array of bytes.
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*/
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public void update(byte[] input)
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{
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engineUpdate(input, 0, input.length);
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}
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/**
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* Completes the hash computation by performing final operations such as
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* padding. The digest is reset after this call is made.
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*
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* @return the array of bytes for the resulting hash value.
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*/
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public byte[] digest()
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{
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return lastDigest = engineDigest();
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}
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/**
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* Completes the hash computation by performing final operations such as
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* padding. The digest is reset after this call is made.
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*
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* @param buf An output buffer for the computed digest.
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* @param offset The offset into the output buffer to begin storing the digest.
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* @param len The number of bytes within buf allotted for the digest.
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* @return The number of bytes placed into buf.
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* @throws DigestException if an error occurs.
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*/
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public int digest(byte[] buf, int offset, int len) throws DigestException
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{
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return engineDigest(buf, offset, len);
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}
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/**
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* Performs a final update on the digest using the specified array of bytes,
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* then completes the digest computation. That is, this method first calls
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* <code>update(input)</code>, passing the input array to the <code>update()
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* </code> method, then calls <code>digest()</code>.
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*
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* @param input the input to be updated before the digest is completed.
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* @return the array of bytes for the resulting hash value.
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*/
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public byte[] digest(byte[] input)
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{
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update(input);
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return digest();
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}
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315 |
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/**
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317 |
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* Returns a string representation of this message digest object.
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318 |
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*
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* @return a string representation of the object.
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*/
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public String toString()
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{
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return (getClass()).getName() + " Message Digest <" + digestToString() + ">";
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}
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/**
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* Compares two digests for equality. Does a simple byte compare.
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*
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* @param digesta one of the digests to compare.
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* @param digestb the other digest to compare.
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* @return <code>true</code> if the digests are equal, <code>false</code>
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* otherwise.
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*/
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public static boolean isEqual(byte[] digesta, byte[] digestb)
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{
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if (digesta.length != digestb.length)
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return false;
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for (int i = digesta.length - 1; i >= 0; --i)
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if (digesta[i] != digestb[i])
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return false;
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return true;
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}
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/** Resets the digest for further use. */
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public void reset()
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{
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engineReset();
|
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}
|
351 |
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|
|
/**
|
353 |
|
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* Returns a string that identifies the algorithm, independent of
|
354 |
|
|
* implementation details. The name should be a standard Java Security name
|
355 |
|
|
* (such as <code>"SHA"</code>, <code>"MD5"</code>, and so on). See Appendix
|
356 |
|
|
* A in the Java Cryptography Architecture API Specification & Reference
|
357 |
|
|
* for information about standard algorithm names.
|
358 |
|
|
*
|
359 |
|
|
* @return the name of the algorithm.
|
360 |
|
|
*/
|
361 |
|
|
public final String getAlgorithm()
|
362 |
|
|
{
|
363 |
|
|
return algorithm;
|
364 |
|
|
}
|
365 |
|
|
|
366 |
|
|
/**
|
367 |
|
|
* Returns the length of the digest in bytes, or <code>0</code> if this
|
368 |
|
|
* operation is not supported by the provider and the implementation is not
|
369 |
|
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* cloneable.
|
370 |
|
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*
|
371 |
|
|
* @return the digest length in bytes, or <code>0</code> if this operation is
|
372 |
|
|
* not supported by the provider and the implementation is not cloneable.
|
373 |
|
|
* @since 1.2
|
374 |
|
|
*/
|
375 |
|
|
public final int getDigestLength()
|
376 |
|
|
{
|
377 |
|
|
return engineGetDigestLength();
|
378 |
|
|
}
|
379 |
|
|
|
380 |
|
|
/**
|
381 |
|
|
* Returns a clone if the implementation is cloneable.
|
382 |
|
|
*
|
383 |
|
|
* @return a clone if the implementation is cloneable.
|
384 |
|
|
* @throws CloneNotSupportedException if this is called on an implementation
|
385 |
|
|
* that does not support {@link Cloneable}.
|
386 |
|
|
*/
|
387 |
|
|
public Object clone() throws CloneNotSupportedException
|
388 |
|
|
{
|
389 |
|
|
return super.clone();
|
390 |
|
|
}
|
391 |
|
|
|
392 |
|
|
private String digestToString()
|
393 |
|
|
{
|
394 |
|
|
byte[] digest = lastDigest;
|
395 |
|
|
|
396 |
|
|
if (digest == null)
|
397 |
|
|
return "incomplete";
|
398 |
|
|
|
399 |
|
|
StringBuffer buf = new StringBuffer();
|
400 |
|
|
int len = digest.length;
|
401 |
|
|
for (int i = 0; i < len; ++i)
|
402 |
|
|
{
|
403 |
|
|
byte b = digest[i];
|
404 |
|
|
byte high = (byte) ((b & 0xff) >>> 4);
|
405 |
|
|
byte low = (byte) (b & 0xf);
|
406 |
|
|
|
407 |
|
|
buf.append(high > 9 ? ('a' - 10) + high : '0' + high);
|
408 |
|
|
buf.append(low > 9 ? ('a' - 10) + low : '0' + low);
|
409 |
|
|
}
|
410 |
|
|
|
411 |
|
|
return buf.toString();
|
412 |
|
|
}
|
413 |
|
|
}
|