398 lines
12 KiB
Java
398 lines
12 KiB
Java
/* SecureRandom.java --- Secure Random class implmentation
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Copyright (C) 1999, 2001, 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., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 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 java.io.Serializable;
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import java.util.Random;
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import java.util.Enumeration;
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/**
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SecureRandom is the class interface for using SecureRandom
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providers. It provides an interface to the SecureRandomSpi
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engine so that programmers can generate pseudo-random numbers.
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@author Mark Benvenuto <ivymccough@worldnet.att.net>
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*/
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public class SecureRandom extends Random
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{
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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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/**
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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 getInstance.
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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, flag = 0;
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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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return;
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}
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catch (Throwable ignore) { }
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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 gnu.java.security.provider.SHA1PRNG();
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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 = secureRandomSpi;
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this.provider = provider;
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}
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/**
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Returns an instance of a SecureRandom. It creates the class
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for the specified algorithm if it exists from a provider.
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@param algorithm A SecureRandom algorithm to use
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@return Returns a new SecureRandom implmenting the chosen algorithm
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@throws NoSuchAlgorithmException if the algorithm cannot be found
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*/
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public static SecureRandom getInstance(String algorithm) throws
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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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// None found.
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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 SecureRandom. It creates the class
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for the specified algorithm from the specified provider.
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@param algorithm A SecureRandom algorithm to use
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@param provider A security provider to use
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@return Returns a new SecureRandom implmenting the chosen algorithm
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@throws NoSuchAlgorithmException if the algorithm cannot be found
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@throws NoSuchProviderException if the provider cannot be found
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*/
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public static SecureRandom getInstance(String algorithm,
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String provider) throws
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NoSuchAlgorithmException, NoSuchProviderException
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{
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Provider p = Security.getProvider(provider);
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if (p == null)
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throw new NoSuchProviderException();
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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 SecureRandom. It creates the class for
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the specified algorithm from the given provider.
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@param algorithm The SecureRandom algorithm to create.
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@param provider The provider to get the instance from.
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@throws NoSuchAlgorithmException If the algorithm cannot be found, or
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if the class cannot be instantiated.
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*/
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public static SecureRandom getInstance(String algorithm,
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Provider provider) throws
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NoSuchAlgorithmException
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{
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return getInstance(algorithm, provider, true);
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}
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/**
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Creates the instance of SecureRandom, recursing to resolve aliases.
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@param algorithm The SecureRandom algorithm to create.
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@param provider The provider to get the implementation from.
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@param recurse Whether or not to recurse to resolve aliases.
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@throws NoSuchAlgorithmException If the algorithm cannot be found,
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if there are too many aliases, or if the class cannot be
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instantiated.
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*/
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private static SecureRandom getInstance(String algorithm,
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Provider provider,
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boolean recurse)
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throws NoSuchAlgorithmException
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{
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String msg = algorithm;
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for (Enumeration e = provider.propertyNames(); e.hasMoreElements(); )
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{
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// We could replace the boolean with an integer, incrementing it
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// every
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String key = (String) e.nextElement();
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if (key.startsWith("SECURERANDOM.")
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&& key.substring(13).equalsIgnoreCase(algorithm))
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{
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try
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{
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Class c = Class.forName(provider.getProperty(key));
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return new SecureRandom((SecureRandomSpi) c.newInstance(),
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provider);
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}
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catch (Throwable ignored) { }
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}
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else if (key.startsWith("ALG.ALIAS.SECURERANDOM.")
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&& key.substring(23).equalsIgnoreCase(algorithm) && recurse)
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{
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try
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{
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// First see if this alias refers to a class in this
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// provider.
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return getInstance(provider.getProperty(key), provider, false);
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}
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catch (NoSuchAlgorithmException nsae)
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{
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Provider[] provs = Security.getProviders();
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for (int i = 0; i < provs.length; i++)
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{
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if (provs[i] == provider)
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continue;
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// Now try other providers for the implementation
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try
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{
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return getInstance(provider.getProperty(key),
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provs[i], false);
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}
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catch (NoSuchAlgorithmException nsae2)
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{
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msg = nsae2.getMessage();
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}
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}
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}
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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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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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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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}
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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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}
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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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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 / 8 + (1 * (numBits % 8))];
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secureRandomSpi.engineNextBytes(tmp);
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randomBytesUsed += tmp.length;
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counter++;
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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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new Random().nextBytes(tmp);
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return tmp;
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//return secureRandomSpi.engineGenerateSeed( numBytes );
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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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}
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