481 lines
15 KiB
Java
481 lines
15 KiB
Java
/* SecureRandom.java --- Secure Random class implementation
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Copyright (C) 1999, 2001, 2002, 2003, 2005, 2006
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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.classpath.SystemProperties;
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import gnu.java.security.Engine;
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import gnu.java.security.action.GetSecurityPropertyAction;
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import gnu.java.security.jce.prng.Sha160RandomSpi;
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import java.io.IOException;
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import java.io.InputStream;
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import java.lang.reflect.InvocationTargetException;
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import java.net.MalformedURLException;
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import java.net.URL;
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import java.util.Enumeration;
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import java.util.Random;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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/**
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* An interface to a cryptographically secure pseudo-random number
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* generator (PRNG). Random (or at least unguessable) numbers are used
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* in all areas of security and cryptography, from the generation of
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* keys and initialization vectors to the generation of random padding
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* bytes.
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*
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* @author Mark Benvenuto (ivymccough@worldnet.att.net)
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* @author Casey Marshall
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*/
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public class SecureRandom extends Random
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{
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// Constants and fields.
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// ------------------------------------------------------------------------
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/** Service name for PRNGs. */
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private static final String SECURE_RANDOM = "SecureRandom";
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private static final long serialVersionUID = 4940670005562187L;
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//Serialized Field
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long counter = 0; //Serialized
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Provider provider = null;
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byte[] randomBytes = null; //Always null
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int randomBytesUsed = 0;
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SecureRandomSpi secureRandomSpi = null;
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byte[] state = null;
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private String algorithm;
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private boolean isSeeded = false;
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// Constructors.
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// ------------------------------------------------------------------------
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/**
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Default constructor for SecureRandom. It constructs a
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new SecureRandom by instantating the first SecureRandom
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algorithm in the default security provier.
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It is not seeded and should be seeded using setSeed or else
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on the first call to getnextBytes it will force a seed.
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It is maintained for backwards compatibility and programs
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should use {@link #getInstance(java.lang.String)}.
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*/
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public SecureRandom()
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{
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Provider[] p = Security.getProviders();
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//Format of Key: SecureRandom.algname
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String key;
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String classname = null;
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int i;
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Enumeration e;
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for (i = 0; i < p.length; i++)
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{
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e = p[i].propertyNames();
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while (e.hasMoreElements())
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{
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key = (String) e.nextElement();
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if (key.startsWith("SECURERANDOM."))
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{
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if ((classname = p[i].getProperty(key)) != null)
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{
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try
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{
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secureRandomSpi = (SecureRandomSpi) Class.
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forName(classname).newInstance();
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provider = p[i];
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algorithm = key.substring(13); // Minus SecureRandom.
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return;
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}
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catch (ThreadDeath death)
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{
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throw death;
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}
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catch (Throwable t)
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{
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// Ignore.
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}
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}
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}
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}
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}
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// Nothing found. Fall back to SHA1PRNG
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secureRandomSpi = new Sha160RandomSpi();
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algorithm = "Sha160";
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}
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/**
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A constructor for SecureRandom. It constructs a new
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SecureRandom by instantating the first SecureRandom algorithm
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in the default security provier.
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It is seeded with the passed function and is useful if the user
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has access to hardware random device (like a radiation detector).
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It is maintained for backwards compatibility and programs
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should use getInstance.
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@param seed Seed bytes for class
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*/
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public SecureRandom(byte[] seed)
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{
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this();
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setSeed(seed);
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}
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/**
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A constructor for SecureRandom. It constructs a new
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SecureRandom using the specified SecureRandomSpi from
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the specified security provier.
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@param secureRandomSpi A SecureRandomSpi class
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@param provider A Provider class
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*/
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protected SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider)
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{
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this(secureRandomSpi, provider, "unknown");
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}
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/**
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* Private constructor called from the getInstance() method.
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*/
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private SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider,
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String algorithm)
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{
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this.secureRandomSpi = secureRandomSpi;
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this.provider = provider;
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this.algorithm = algorithm;
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}
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/**
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* Returns an instance of a <code>SecureRandom</code> from the first provider
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* that implements it.
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*
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* @param algorithm The algorithm name.
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* @return A new <code>SecureRandom</code> implementing the given algorithm.
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* @throws NoSuchAlgorithmException If no installed provider implements the
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* given algorithm.
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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 SecureRandom 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 an instance of a <code>SecureRandom</code> for the specified
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* algorithm from the named provider.
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*
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* @param algorithm The algorithm name.
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* @param provider The provider name.
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* @return A new <code>SecureRandom</code> implementing the chosen
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* algorithm.
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* @throws NoSuchAlgorithmException If the named provider does not implement
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* the algorithm, or if the implementation cannot be instantiated.
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* @throws NoSuchProviderException If no provider named <code>provider</code>
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* is currently installed.
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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 SecureRandom 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 an instance of a <code>SecureRandom</code> for the specified
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* algorithm from the given provider.
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*
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* @param algorithm The <code>SecureRandom</code> algorithm to create.
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* @param provider The provider to use.
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* @throws NoSuchAlgorithmException If the algorithm cannot be found, or if
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* the class cannot be instantiated.
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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 SecureRandom getInstance(String algorithm, Provider provider)
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throws NoSuchAlgorithmException
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{
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StringBuilder sb = new StringBuilder("SecureRandom for 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(SECURE_RANDOM, algorithm, provider);
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return new SecureRandom((SecureRandomSpi) 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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Returns the provider being used by the current SecureRandom class.
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@return The provider from which this SecureRandom was attained
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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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* Returns the algorithm name used or "unknown" when the algorithm
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* used couldn't be determined (as when constructed by the protected
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* 2 argument constructor).
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*
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* @since 1.5
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*/
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public String getAlgorithm()
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{
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return algorithm;
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}
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/**
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Seeds the SecureRandom. The class is re-seeded for each call and
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each seed builds on the previous seed so as not to weaken security.
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@param seed seed bytes to seed with
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*/
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public void setSeed(byte[] seed)
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{
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secureRandomSpi.engineSetSeed(seed);
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isSeeded = true;
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}
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/**
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Seeds the SecureRandom. The class is re-seeded for each call and
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each seed builds on the previous seed so as not to weaken security.
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@param seed 8 seed bytes to seed with
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*/
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public void setSeed(long seed)
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{
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// This particular setSeed will be called by Random.Random(), via
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// our own constructor, before secureRandomSpi is initialized. In
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// this case we can't call a method on secureRandomSpi, and we
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// definitely don't want to throw a NullPointerException.
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// Therefore we test.
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if (secureRandomSpi != null)
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{
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byte[] tmp = { (byte) (0xff & (seed >> 56)),
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(byte) (0xff & (seed >> 48)),
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(byte) (0xff & (seed >> 40)),
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(byte) (0xff & (seed >> 32)),
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(byte) (0xff & (seed >> 24)),
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(byte) (0xff & (seed >> 16)),
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(byte) (0xff & (seed >> 8)),
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(byte) (0xff & seed)
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};
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secureRandomSpi.engineSetSeed(tmp);
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isSeeded = true;
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}
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}
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/**
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Generates a user specified number of bytes. This function
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is the basis for all the random functions.
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@param bytes array to store generated bytes in
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*/
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public void nextBytes(byte[] bytes)
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{
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if (!isSeeded)
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setSeed(getSeed(32));
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randomBytesUsed += bytes.length;
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counter++;
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secureRandomSpi.engineNextBytes(bytes);
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}
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/**
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Generates an integer containing the user specified
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number of random bits. It is right justified and padded
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with zeros.
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@param numBits number of random bits to get, 0 <= numBits <= 32;
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@return the random bits
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*/
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protected final int next(int numBits)
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{
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if (numBits == 0)
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return 0;
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byte[] tmp = new byte[(numBits + 7) / 8];
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this.nextBytes(tmp);
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int ret = 0;
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for (int i = 0; i < tmp.length; i++)
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ret |= (tmp[i] & 0xFF) << (8 * i);
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long mask = (1L << numBits) - 1;
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return (int) (ret & mask);
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}
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/**
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Returns the given number of seed bytes. This method is
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maintained only for backwards capability.
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@param numBytes number of seed bytes to get
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@return an array containing the seed bytes
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*/
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public static byte[] getSeed(int numBytes)
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{
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byte[] tmp = new byte[numBytes];
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generateSeed(tmp);
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return tmp;
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}
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/**
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Returns the specified number of seed bytes.
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@param numBytes number of seed bytes to get
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@return an array containing the seed bytes
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*/
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public byte[] generateSeed(int numBytes)
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{
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return secureRandomSpi.engineGenerateSeed(numBytes);
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}
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// Seed methods.
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private static final String SECURERANDOM_SOURCE = "securerandom.source";
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private static final String JAVA_SECURITY_EGD = "java.security.egd";
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private static final Logger logger = Logger.getLogger(SecureRandom.class.getName());
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private static int generateSeed(byte[] buffer)
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{
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return generateSeed(buffer, 0, buffer.length);
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}
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private static int generateSeed(byte[] buffer, int offset, int length)
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{
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URL sourceUrl = null;
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String urlStr = null;
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GetSecurityPropertyAction action = new GetSecurityPropertyAction(SECURERANDOM_SOURCE);
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try
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{
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urlStr = (String) AccessController.doPrivileged(action);
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if (urlStr != null)
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sourceUrl = new URL(urlStr);
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}
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catch (MalformedURLException ignored)
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{
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logger.log(Level.WARNING, SECURERANDOM_SOURCE + " property is malformed: {0}",
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urlStr);
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}
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if (sourceUrl == null)
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{
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try
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{
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urlStr = SystemProperties.getProperty(JAVA_SECURITY_EGD);
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if (urlStr != null)
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sourceUrl = new URL(urlStr);
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}
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catch (MalformedURLException mue)
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{
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logger.log(Level.WARNING, JAVA_SECURITY_EGD + " property is malformed: {0}",
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urlStr);
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}
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}
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if (sourceUrl != null)
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{
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try
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{
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InputStream in = sourceUrl.openStream();
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return in.read(buffer, offset, length);
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}
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catch (IOException ioe)
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{
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logger.log(Level.FINE, "error reading random bytes", ioe);
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}
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}
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// If we get here, we did not get any seed from a property URL.
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return VMSecureRandom.generateSeed(buffer, offset, length);
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}
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}
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