381 lines
11 KiB
Java
381 lines
11 KiB
Java
/* MessageDigest.java --- The message digest interface.
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Copyright (C) 1999, 2002, 2003, 2006 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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import java.nio.ByteBuffer;
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import java.lang.reflect.InvocationTargetException;
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/**
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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.
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*
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* @see MessageDigestSpi
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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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* Constructs a new instance of <code>MessageDigest</code> representing the
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* specified algorithm.
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*
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* @param algorithm
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* the name of the digest algorithm to use.
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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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* Returns a new instance of <code>MessageDigest</code> representing the
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* specified algorithm.
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*
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* @param algorithm the name of the digest algorithm to use.
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* @return a new instance representing the desired algorithm.
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* @throws NoSuchAlgorithmException if the algorithm is not implemented by any
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* 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 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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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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* Returns a new instance of <code>MessageDigest</code> representing the
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* specified algorithm from a named provider.
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*
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* @param algorithm the name of the digest algorithm to use.
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* @param provider the name of the provider to use.
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* @return a new instance representing the desired algorithm.
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* @throws NoSuchAlgorithmException if the algorithm is not implemented by the
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* named provider.
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* @throws NoSuchProviderException if the named provider was not found.
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* @throws IllegalArgumentException if either <code>algorithm</code> or
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* <code>provider</code> is <code>null</code> or empty.
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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)
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throw new IllegalArgumentException("provider MUST NOT be null");
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provider = provider.trim();
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if (provider.length() == 0)
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throw new IllegalArgumentException("provider MUST NOT be empty");
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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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* Returns a new instance of <code>MessageDigest</code> representing the
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* specified algorithm from a designated {@link Provider}.
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*
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* @param algorithm the name of the digest algorithm to use.
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* @param provider the {@link Provider} to use.
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* @return a new instance representing the desired algorithm.
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* @throws NoSuchAlgorithmException if the algorithm is not implemented by
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* {@link Provider}.
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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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* @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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StringBuilder sb = new StringBuilder("MessageDigest for algorithm [")
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.append(algorithm).append("] from provider[")
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.append(provider).append("] ");
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Object o;
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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 (InvocationTargetException x)
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{
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Throwable 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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sb.append("could not be created");
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NoSuchAlgorithmException y = new NoSuchAlgorithmException(sb.toString());
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y.initCause(cause);
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throw y;
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}
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MessageDigest result;
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if (o instanceof MessageDigestSpi)
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result = new DummyMessageDigest((MessageDigestSpi) o, algorithm);
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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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sb.append("is of an unexpected Type: ").append(o.getClass().getName());
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throw new NoSuchAlgorithmException(sb.toString());
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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 {@link Provider} of this instance.
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*
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* @return the {@link Provider} of this instance.
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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 with the byte.
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*
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* @param input byte to update the digest with.
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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 with the bytes from the array starting from the
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* specified offset and using the specified length of bytes.
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*
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* @param input
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* bytes to update the digest with.
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* @param offset
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* the offset to start at.
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* @param len
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* length of the data to update with.
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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 with the bytes of an array.
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*
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* @param input bytes to update the digest with.
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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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* Updates the digest with the remaining bytes of a buffer.
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*
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* @param input The input byte buffer.
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* @since 1.5
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*/
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public void update (ByteBuffer input)
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{
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engineUpdate (input);
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}
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/**
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* Computes the final digest of the stored data.
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*
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* @return a byte array representing the message digest.
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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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* Computes the final digest of the stored bytes and returns the result.
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*
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* @param buf
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* an array of bytes to store the result in.
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* @param offset
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* an offset to start storing the result at.
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* @param len
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* the length of the buffer.
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* @return Returns the length of the buffer.
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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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* Computes a final update using the input array of bytes, then computes a
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* final digest and returns it. It calls {@link #update(byte[])} and then
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* {@link #digest(byte[])}.
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*
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* @param input
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* an array of bytes to perform final update with.
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* @return a byte array representing the message digest.
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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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/**
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* Returns a string representation of this instance.
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*
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* @return a string representation of this instance.
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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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* Does a simple byte comparison of the two digests.
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*
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* @param digesta
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* first digest to compare.
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* @param digestb
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* second digest to compare.
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* @return <code>true</code> if both 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 this instance. */
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public void reset()
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{
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engineReset();
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}
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/**
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* Returns the name of message digest algorithm.
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*
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* @return the name of message digest algorithm.
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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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* Returns the length of the message digest. The default is zero which means
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* that the concrete implementation does not implement this method.
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*
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* @return length of the message digest.
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* @since 1.2
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*/
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public final int getDigestLength()
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{
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return engineGetDigestLength();
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}
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/**
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* Returns a clone of this instance if cloning is supported. If it does not
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* then a {@link CloneNotSupportedException} is thrown. Cloning depends on
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* whether the subclass {@link MessageDigestSpi} implements {@link Cloneable}
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* which contains the actual implementation of the appropriate algorithm.
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*
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* @return a clone of this instance.
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* @throws CloneNotSupportedException
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* the implementation does not support cloning.
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*/
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public Object clone() throws CloneNotSupportedException
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{
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return super.clone();
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}
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private String digestToString()
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{
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byte[] digest = lastDigest;
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if (digest == null)
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return "incomplete";
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StringBuffer buf = new StringBuffer();
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int len = digest.length;
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for (int i = 0; i < len; ++i)
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{
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byte b = digest[i];
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byte high = (byte) ((b & 0xff) >>> 4);
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byte low = (byte) (b & 0xf);
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buf.append(high > 9 ? ('a' - 10) + high : '0' + high);
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buf.append(low > 9 ? ('a' - 10) + low : '0' + low);
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}
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return buf.toString();
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}
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}
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