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/*
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* Copyright 1996-2006 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Sun designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Sun in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*/
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package java.security;
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import java.util.*;
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import java.security.Provider.Service;
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import sun.security.jca.*;
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import sun.security.jca.GetInstance.Instance;
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/**
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* This class provides a cryptographically strong random number
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* generator (RNG).
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*
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* <p>A cryptographically strong random number
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* minimally complies with the statistical random number generator tests
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* specified in <a href="http://csrc.nist.gov/cryptval/140-2.htm">
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* <i>FIPS 140-2, Security Requirements for Cryptographic Modules</i></a>,
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* section 4.9.1.
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* Additionally, SecureRandom must produce non-deterministic output.
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* Therefore any seed material passed to a SecureRandom object must be
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* unpredictable, and all SecureRandom output sequences must be
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* cryptographically strong, as described in
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* <a href="http://www.ietf.org/rfc/rfc1750.txt">
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* <i>RFC 1750: Randomness Recommendations for Security</i></a>.
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*
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* <p>A caller obtains a SecureRandom instance via the
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* no-argument constructor or one of the <code>getInstance</code> methods:
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*
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* <pre>
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* SecureRandom random = new SecureRandom();
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* </pre>
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*
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* <p> Many SecureRandom implementations are in the form of a pseudo-random
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* number generator (PRNG), which means they use a deterministic algorithm
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* to produce a pseudo-random sequence from a true random seed.
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* Other implementations may produce true random numbers,
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* and yet others may use a combination of both techniques.
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*
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* <p> Typical callers of SecureRandom invoke the following methods
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* to retrieve random bytes:
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*
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* <pre>
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* SecureRandom random = new SecureRandom();
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* byte bytes[] = new byte[20];
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* random.nextBytes(bytes);
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* </pre>
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*
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* <p> Callers may also invoke the <code>generateSeed</code> method
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* to generate a given number of seed bytes (to seed other random number
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* generators, for example):
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* <pre>
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* byte seed[] = random.generateSeed(20);
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* </pre>
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*
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* Note: Depending on the implementation, the <code>generateSeed</code> and
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* <code>nextBytes</code> methods may block as entropy is being gathered,
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* for example, if they need to read from /dev/random on various unix-like
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* operating systems.
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*
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* @see java.security.SecureRandomSpi
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* @see java.util.Random
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*
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* @author Benjamin Renaud
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* @author Josh Bloch
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*/
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public class SecureRandom extends java.util.Random {
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/**
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* The provider.
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*
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* @serial
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* @since 1.2
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*/
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private Provider provider = null;
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/**
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* The provider implementation.
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*
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* @serial
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* @since 1.2
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*/
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private SecureRandomSpi secureRandomSpi = null;
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/*
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* The algorithm name of null if unknown.
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*
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* @serial
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* @since 1.5
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*/
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private String algorithm;
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// Seed Generator
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private static volatile SecureRandom seedGenerator = null;
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/**
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* Constructs a secure random number generator (RNG) implementing the
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* default random number algorithm.
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*
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* <p> This constructor traverses the list of registered security Providers,
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* starting with the most preferred Provider.
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* A new SecureRandom object encapsulating the
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* SecureRandomSpi implementation from the first
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* Provider that supports a SecureRandom (RNG) algorithm is returned.
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* If none of the Providers support a RNG algorithm,
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* then an implementation-specific default is returned.
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*
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* <p> Note that the list of registered providers may be retrieved via
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* the {@link Security#getProviders() Security.getProviders()} method.
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*
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* <p> See Appendix A in the <a href=
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* "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
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* Java Cryptography Architecture API Specification & Reference </a>
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* for information about standard RNG algorithm names.
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*
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* <p> The returned SecureRandom object has not been seeded. To seed the
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* returned object, call the <code>setSeed</code> method.
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* If <code>setSeed</code> is not called, the first call to
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* <code>nextBytes</code> will force the SecureRandom object to seed itself.
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* This self-seeding will not occur if <code>setSeed</code> was
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* previously called.
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*/
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public SecureRandom() {
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/*
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* This call to our superclass constructor will result in a call
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* to our own <code>setSeed</code> method, which will return
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* immediately when it is passed zero.
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*/
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super(0);
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getDefaultPRNG(false, null);
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}
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/**
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* Constructs a secure random number generator (RNG) implementing the
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* default random number algorithm.
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* The SecureRandom instance is seeded with the specified seed bytes.
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*
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* <p> This constructor traverses the list of registered security Providers,
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* starting with the most preferred Provider.
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* A new SecureRandom object encapsulating the
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* SecureRandomSpi implementation from the first
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* Provider that supports a SecureRandom (RNG) algorithm is returned.
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* If none of the Providers support a RNG algorithm,
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* then an implementation-specific default is returned.
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*
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* <p> Note that the list of registered providers may be retrieved via
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* the {@link Security#getProviders() Security.getProviders()} method.
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*
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* <p> See Appendix A in the <a href=
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* "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
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* Java Cryptography Architecture API Specification & Reference </a>
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* for information about standard RNG algorithm names.
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*
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* @param seed the seed.
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*/
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public SecureRandom(byte seed[]) {
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super(0);
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getDefaultPRNG(true, seed);
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}
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private void getDefaultPRNG(boolean setSeed, byte[] seed) {
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String prng = getPrngAlgorithm();
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if (prng == null) {
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// bummer, get the SUN implementation
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prng = "SHA1PRNG";
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this.secureRandomSpi = new sun.security.provider.SecureRandom();
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this.provider = Providers.getSunProvider();
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if (setSeed) {
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this.secureRandomSpi.engineSetSeed(seed);
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}
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} else {
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try {
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SecureRandom random = SecureRandom.getInstance(prng);
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this.secureRandomSpi = random.getSecureRandomSpi();
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this.provider = random.getProvider();
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if (setSeed) {
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this.secureRandomSpi.engineSetSeed(seed);
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}
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} catch (NoSuchAlgorithmException nsae) {
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// never happens, because we made sure the algorithm exists
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throw new RuntimeException(nsae);
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}
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}
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// JDK 1.1 based implementations subclass SecureRandom instead of
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// SecureRandomSpi. They will also go through this code path because
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// they must call a SecureRandom constructor as it is their superclass.
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// If we are dealing with such an implementation, do not set the
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// algorithm value as it would be inaccurate.
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if (getClass() == SecureRandom.class) {
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this.algorithm = prng;
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}
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}
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/**
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* Creates a SecureRandom object.
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*
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* @param secureRandomSpi the SecureRandom implementation.
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* @param provider the provider.
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*/
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protected SecureRandom(SecureRandomSpi secureRandomSpi,
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Provider provider) {
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this(secureRandomSpi, provider, null);
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}
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private SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider,
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String algorithm) {
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super(0);
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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 a SecureRandom object that implements the specified
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* Random Number Generator (RNG) algorithm.
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*
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* <p> This method traverses the list of registered security Providers,
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* starting with the most preferred Provider.
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* A new SecureRandom object encapsulating the
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* SecureRandomSpi implementation from the first
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* Provider that supports the specified algorithm is returned.
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*
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* <p> Note that the list of registered providers may be retrieved via
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* the {@link Security#getProviders() Security.getProviders()} method.
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*
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* <p> The returned SecureRandom object has not been seeded. To seed the
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* returned object, call the <code>setSeed</code> method.
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* If <code>setSeed</code> is not called, the first call to
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* <code>nextBytes</code> will force the SecureRandom object to seed itself.
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* This self-seeding will not occur if <code>setSeed</code> was
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* previously called.
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*
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* @param algorithm the name of the RNG algorithm.
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* See Appendix A in the <a href=
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* "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
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* Java Cryptography Architecture API Specification & Reference </a>
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* for information about standard RNG algorithm names.
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*
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* @return the new SecureRandom object.
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*
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* @exception NoSuchAlgorithmException if no Provider supports a
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* SecureRandomSpi implementation for the
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* specified algorithm.
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*
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* @see Provider
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*
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* @since 1.2
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*/
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public static SecureRandom getInstance(String algorithm)
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throws NoSuchAlgorithmException {
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Instance instance = GetInstance.getInstance("SecureRandom",
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SecureRandomSpi.class, algorithm);
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return new SecureRandom((SecureRandomSpi)instance.impl,
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instance.provider, algorithm);
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}
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/**
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* Returns a SecureRandom object that implements the specified
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* Random Number Generator (RNG) algorithm.
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*
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* <p> A new SecureRandom object encapsulating the
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* SecureRandomSpi implementation from the specified provider
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* is returned. The specified provider must be registered
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* in the security provider list.
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*
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* <p> Note that the list of registered providers may be retrieved via
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* the {@link Security#getProviders() Security.getProviders()} method.
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*
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* <p> The returned SecureRandom object has not been seeded. To seed the
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* returned object, call the <code>setSeed</code> method.
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* If <code>setSeed</code> is not called, the first call to
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* <code>nextBytes</code> will force the SecureRandom object to seed itself.
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* This self-seeding will not occur if <code>setSeed</code> was
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* previously called.
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*
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* @param algorithm the name of the RNG algorithm.
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* See Appendix A in the <a href=
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* "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
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* Java Cryptography Architecture API Specification & Reference </a>
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* for information about standard RNG algorithm names.
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*
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* @param provider the name of the provider.
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*
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* @return the new SecureRandom object.
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*
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* @exception NoSuchAlgorithmException if a SecureRandomSpi
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* implementation for the specified algorithm is not
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* available from the specified provider.
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*
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* @exception NoSuchProviderException if the specified provider is not
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* registered in the security provider list.
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*
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* @exception IllegalArgumentException if the provider name is null
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* or empty.
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*
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* @see Provider
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*
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* @since 1.2
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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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Instance instance = GetInstance.getInstance("SecureRandom",
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SecureRandomSpi.class, algorithm, provider);
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return new SecureRandom((SecureRandomSpi)instance.impl,
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instance.provider, algorithm);
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}
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/**
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* Returns a SecureRandom object that implements the specified
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* Random Number Generator (RNG) algorithm.
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*
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* <p> A new SecureRandom object encapsulating the
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* SecureRandomSpi implementation from the specified Provider
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* object is returned. Note that the specified Provider object
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* does not have to be registered in the provider list.
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*
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* <p> The returned SecureRandom object has not been seeded. To seed the
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* returned object, call the <code>setSeed</code> method.
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* If <code>setSeed</code> is not called, the first call to
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* <code>nextBytes</code> will force the SecureRandom object to seed itself.
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* This self-seeding will not occur if <code>setSeed</code> was
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* previously called.
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*
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* @param algorithm the name of the RNG algorithm.
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* See Appendix A in the <a href=
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* "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
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* Java Cryptography Architecture API Specification & Reference </a>
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* for information about standard RNG algorithm names.
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*
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* @param provider the provider.
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*
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* @return the new SecureRandom object.
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*
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* @exception NoSuchAlgorithmException if a SecureRandomSpi
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* implementation for the specified algorithm is not available
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* from the specified Provider object.
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*
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* @exception IllegalArgumentException if the specified provider is null.
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*
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* @see Provider
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*
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* @since 1.4
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*/
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public static SecureRandom getInstance(String algorithm,
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Provider provider) throws NoSuchAlgorithmException {
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Instance instance = GetInstance.getInstance("SecureRandom",
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SecureRandomSpi.class, algorithm, provider);
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return new SecureRandom((SecureRandomSpi)instance.impl,
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instance.provider, algorithm);
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}
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/**
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* Returns the SecureRandomSpi of this SecureRandom object.
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*/
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SecureRandomSpi getSecureRandomSpi() {
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return secureRandomSpi;
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}
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/**
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* Returns the provider of this SecureRandom object.
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*
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* @return the provider of this SecureRandom object.
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*/
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public final Provider getProvider() {
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return provider;
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}
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/**
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* Returns the name of the algorithm implemented by this SecureRandom
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* object.
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*
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* @return the name of the algorithm or <code>unknown</code>
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* if the algorithm name cannot be determined.
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* @since 1.5
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*/
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public String getAlgorithm() {
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return (algorithm != null) ? algorithm : "unknown";
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}
|
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|
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405 |
/**
|
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* Reseeds this random object. The given seed supplements, rather than
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* replaces, the existing seed. Thus, repeated calls are guaranteed
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408 |
* never to reduce randomness.
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*
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* @param seed the seed.
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*
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|
412 |
* @see #getSeed
|
|
413 |
*/
|
|
414 |
synchronized public void setSeed(byte[] seed) {
|
|
415 |
secureRandomSpi.engineSetSeed(seed);
|
|
416 |
}
|
|
417 |
|
|
418 |
/**
|
|
419 |
* Reseeds this random object, using the eight bytes contained
|
|
420 |
* in the given <code>long seed</code>. The given seed supplements,
|
|
421 |
* rather than replaces, the existing seed. Thus, repeated calls
|
|
422 |
* are guaranteed never to reduce randomness.
|
|
423 |
*
|
|
424 |
* <p>This method is defined for compatibility with
|
|
425 |
* <code>java.util.Random</code>.
|
|
426 |
*
|
|
427 |
* @param seed the seed.
|
|
428 |
*
|
|
429 |
* @see #getSeed
|
|
430 |
*/
|
|
431 |
public void setSeed(long seed) {
|
|
432 |
/*
|
|
433 |
* Ignore call from super constructor (as well as any other calls
|
|
434 |
* unfortunate enough to be passing 0). It's critical that we
|
|
435 |
* ignore call from superclass constructor, as digest has not
|
|
436 |
* yet been initialized at that point.
|
|
437 |
*/
|
|
438 |
if (seed != 0) {
|
|
439 |
secureRandomSpi.engineSetSeed(longToByteArray(seed));
|
|
440 |
}
|
|
441 |
}
|
|
442 |
|
|
443 |
/**
|
|
444 |
* Generates a user-specified number of random bytes.
|
|
445 |
*
|
|
446 |
* <p> If a call to <code>setSeed</code> had not occurred previously,
|
|
447 |
* the first call to this method forces this SecureRandom object
|
|
448 |
* to seed itself. This self-seeding will not occur if
|
|
449 |
* <code>setSeed</code> was previously called.
|
|
450 |
*
|
|
451 |
* @param bytes the array to be filled in with random bytes.
|
|
452 |
*/
|
|
453 |
|
|
454 |
synchronized public void nextBytes(byte[] bytes) {
|
|
455 |
secureRandomSpi.engineNextBytes(bytes);
|
|
456 |
}
|
|
457 |
|
|
458 |
/**
|
|
459 |
* Generates an integer containing the user-specified number of
|
|
460 |
* pseudo-random bits (right justified, with leading zeros). This
|
|
461 |
* method overrides a <code>java.util.Random</code> method, and serves
|
|
462 |
* to provide a source of random bits to all of the methods inherited
|
|
463 |
* from that class (for example, <code>nextInt</code>,
|
|
464 |
* <code>nextLong</code>, and <code>nextFloat</code>).
|
|
465 |
*
|
|
466 |
* @param numBits number of pseudo-random bits to be generated, where
|
|
467 |
* 0 <= <code>numBits</code> <= 32.
|
|
468 |
*
|
|
469 |
* @return an <code>int</code> containing the user-specified number
|
|
470 |
* of pseudo-random bits (right justified, with leading zeros).
|
|
471 |
*/
|
|
472 |
final protected int next(int numBits) {
|
|
473 |
int numBytes = (numBits+7)/8;
|
|
474 |
byte b[] = new byte[numBytes];
|
|
475 |
int next = 0;
|
|
476 |
|
|
477 |
nextBytes(b);
|
|
478 |
for (int i = 0; i < numBytes; i++)
|
|
479 |
next = (next << 8) + (b[i] & 0xFF);
|
|
480 |
|
|
481 |
return next >>> (numBytes*8 - numBits);
|
|
482 |
}
|
|
483 |
|
|
484 |
/**
|
|
485 |
* Returns the given number of seed bytes, computed using the seed
|
|
486 |
* generation algorithm that this class uses to seed itself. This
|
|
487 |
* call may be used to seed other random number generators.
|
|
488 |
*
|
|
489 |
* <p>This method is only included for backwards compatibility.
|
|
490 |
* The caller is encouraged to use one of the alternative
|
|
491 |
* <code>getInstance</code> methods to obtain a SecureRandom object, and
|
|
492 |
* then call the <code>generateSeed</code> method to obtain seed bytes
|
|
493 |
* from that object.
|
|
494 |
*
|
|
495 |
* @param numBytes the number of seed bytes to generate.
|
|
496 |
*
|
|
497 |
* @return the seed bytes.
|
|
498 |
*
|
|
499 |
* @see #setSeed
|
|
500 |
*/
|
|
501 |
public static byte[] getSeed(int numBytes) {
|
|
502 |
if (seedGenerator == null)
|
|
503 |
seedGenerator = new SecureRandom();
|
|
504 |
return seedGenerator.generateSeed(numBytes);
|
|
505 |
}
|
|
506 |
|
|
507 |
/**
|
|
508 |
* Returns the given number of seed bytes, computed using the seed
|
|
509 |
* generation algorithm that this class uses to seed itself. This
|
|
510 |
* call may be used to seed other random number generators.
|
|
511 |
*
|
|
512 |
* @param numBytes the number of seed bytes to generate.
|
|
513 |
*
|
|
514 |
* @return the seed bytes.
|
|
515 |
*/
|
|
516 |
public byte[] generateSeed(int numBytes) {
|
|
517 |
return secureRandomSpi.engineGenerateSeed(numBytes);
|
|
518 |
}
|
|
519 |
|
|
520 |
/**
|
|
521 |
* Helper function to convert a long into a byte array (least significant
|
|
522 |
* byte first).
|
|
523 |
*/
|
|
524 |
private static byte[] longToByteArray(long l) {
|
|
525 |
byte[] retVal = new byte[8];
|
|
526 |
|
|
527 |
for (int i = 0; i < 8; i++) {
|
|
528 |
retVal[i] = (byte) l;
|
|
529 |
l >>= 8;
|
|
530 |
}
|
|
531 |
|
|
532 |
return retVal;
|
|
533 |
}
|
|
534 |
|
|
535 |
/**
|
|
536 |
* Gets a default PRNG algorithm by looking through all registered
|
|
537 |
* providers. Returns the first PRNG algorithm of the first provider that
|
|
538 |
* has registered a SecureRandom implementation, or null if none of the
|
|
539 |
* registered providers supplies a SecureRandom implementation.
|
|
540 |
*/
|
|
541 |
private static String getPrngAlgorithm() {
|
|
542 |
for (Provider p : Providers.getProviderList().providers()) {
|
|
543 |
for (Service s : p.getServices()) {
|
|
544 |
if (s.getType().equals("SecureRandom")) {
|
|
545 |
return s.getAlgorithm();
|
|
546 |
}
|
|
547 |
}
|
|
548 |
}
|
|
549 |
return null;
|
|
550 |
}
|
|
551 |
|
|
552 |
// Declare serialVersionUID to be compatible with JDK1.1
|
|
553 |
static final long serialVersionUID = 4940670005562187L;
|
|
554 |
|
|
555 |
// Retain unused values serialized from JDK1.1
|
|
556 |
/**
|
|
557 |
* @serial
|
|
558 |
*/
|
|
559 |
private byte[] state;
|
|
560 |
/**
|
|
561 |
* @serial
|
|
562 |
*/
|
|
563 |
private MessageDigest digest = null;
|
|
564 |
/**
|
|
565 |
* @serial
|
|
566 |
*
|
|
567 |
* We know that the MessageDigest class does not implement
|
|
568 |
* java.io.Serializable. However, since this field is no longer
|
|
569 |
* used, it will always be NULL and won't affect the serialization
|
|
570 |
* of the SecureRandom class itself.
|
|
571 |
*/
|
|
572 |
private byte[] randomBytes;
|
|
573 |
/**
|
|
574 |
* @serial
|
|
575 |
*/
|
|
576 |
private int randomBytesUsed;
|
|
577 |
/**
|
|
578 |
* @serial
|
|
579 |
*/
|
|
580 |
private long counter;
|
|
581 |
}
|