Java tutorial
/* * RRZEPwGen, developed as a part of the IDMOne project at RRZE. * Copyright 2007, RRZE, and individual contributors * as indicated by the @author tags. See the copyright.txt file in the * distribution for a full listing of individual contributors. This * product includes software developed by the Apache Software Foundation * http://www.apache.org/ * * This is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as * published by the Free Software Foundation; either version 2.1 of * the License, or (at your option) any later version. * * This software is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this software; if not, write to the Free * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA * 02110-1301 USA, or see the FSF site: http://www.fsf.org. * * */ package de.rrze.idmone.utils.jpwgen; import java.security.NoSuchAlgorithmException; import java.security.NoSuchProviderException; import java.security.Provider; import java.security.SecureRandom; import java.security.Security; import java.util.HashSet; import java.util.Iterator; import java.util.Random; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * A singleton that provides various */ public class RandomFactory implements IRandomFactory { // The class instance private static RandomFactory instance; // The class logger private static final Log logger = LogFactory.getLog(RandomFactory.class); /** * Accessor to the instance * * @return the singleton instance */ public static RandomFactory getInstance() { if (instance == null) instance = new RandomFactory(); return instance; } /** * Constructor */ private RandomFactory() { } /** * Create a two pseudo random generator by utilizing the * <em>SecureRandom</em> class provided by SUN. Uses a two step procedure * for feeding the generator seed with two separate SecureRandom instances. * * @see http * ://java.sun.com/j2se/1.4.2/docs/api/java/security/SecureRandom.html * * @param algorithm * The algorithm used for creating the pseudo random generator * @param provider * the provider identifier * @return a seeded <em>SecureRandom</em> * @throws NoSuchAlgorithmException * @throws NoSuchProviderException */ private SecureRandom initSecureRandom(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException { logger.debug("Initializing random with: " + algorithm + " : " + provider); if (provider == null) provider = PROVIDER_DEFAULT; // Create a secure random number generator SecureRandom sr = SecureRandom.getInstance(algorithm, provider); // Get 1024 random bits byte[] bytes = new byte[1024 / 8]; sr.nextBytes(bytes); // Create two secure number generators with the same seed int seedByteCount = 10; byte[] seed = sr.generateSeed(seedByteCount); sr = SecureRandom.getInstance(algorithm, provider); sr.setSeed(seed); SecureRandom sr2 = SecureRandom.getInstance(algorithm, provider); sr2.setSeed(seed); return sr2; } /* * (non-Javadoc) * * @see de.rrze.idmone.utils.pwgen.IRandomFactory#getAlgorithms() */ @SuppressWarnings({ "rawtypes", "unchecked" }) public Set<String> getAlgorithms() { Set<String> result = new HashSet<String>(); // All providers Provider[] providers = Security.getProviders(); for (int i = 0; i < providers.length; i++) { // Get services provided by each provider Set keys = providers[i].keySet(); for (Iterator<String> it = keys.iterator(); it.hasNext();) { String key = (String) it.next(); String value = (String) providers[i].get(key); result.add(value); } } return result; } /** * Returns a cleaned up version of the service providers. * * @return a set of service providers that can be used for SecureRandom * feed. */ @SuppressWarnings({ "rawtypes", "unchecked" }) public Set<String> getServiceProviders() { Set<String> result = new HashSet<String>(); // All providers Provider[] providers = Security.getProviders(); for (int i = 0; i < providers.length; i++) { // Get services provided by each provider Set keys = providers[i].keySet(); for (Iterator<String> it = keys.iterator(); it.hasNext();) { String key = (String) it.next(); key = key.split(" ")[0]; //$NON-NLS-1$ if (key.startsWith(ALG_PARSE_STRING)) { // Strip the alias key = key.substring(10); } int ix = key.indexOf('.'); result.add(key.substring(0, ix)); } } return result; } /* * (non-Javadoc) * * @see * de.rrze.idmone.utils.pwgen.IRandomFactory#getServiceProviderFor(java. * lang.String) */ @SuppressWarnings("rawtypes") public Set<String> getServiceProviderFor(String type) { Set<String> result = new HashSet<String>(); Provider[] providers = Security.getProviders(); for (int i = 0; i < providers.length; i++) { // Get services provided by each provider Set keys = providers[i].keySet(); for (Iterator it = keys.iterator(); it.hasNext();) { String key = (String) it.next(); key = key.split(" ")[0]; //$NON-NLS-1$ if (key.startsWith(type + ".")) //$NON-NLS-1$ { result.add(key.substring(type.length() + 1)); } else if (key.startsWith(ALG_PARSE_STRING + type + ".")) //$NON-NLS-1$ { // This is an alias result.add(key.substring(type.length() + 11)); } } } return result; } /* * (non-Javadoc) * * @see de.rrze.idmone.utils.pwgen.IRandomFactory#getProviders() */ public Provider[] getProviders() { return Security.getProviders(); } /* * (non-Javadoc) * * @see de.rrze.idmone.utils.pwgen.IRandomFactory#getRandom() */ public Random getRandom() { return new Random(System.currentTimeMillis()); } /* * (non-Javadoc) * * @see de.rrze.idmone.utils.pwgen.IRandomFactory#getRandom(long) */ public Random getRandom(long seed) { return new Random(seed); } /* * (non-Javadoc) * * @see de.rrze.idmone.utils.pwgen.IRandomFactory#getSecureRandom() */ public Random getSecureRandom() throws NoSuchAlgorithmException, NoSuchProviderException { return initSecureRandom(ALG_SHA1PRNG, null); } /* * (non-Javadoc) * * @see * de.rrze.idmone.utils.pwgen.IRandomFactory#getSecureRandom(java.lang.String * ) */ public Random getSecureRandom(String algorithm) throws NoSuchAlgorithmException, NoSuchProviderException { return initSecureRandom(algorithm, null); } /* * (non-Javadoc) * * @see * de.rrze.idmone.utils.pwgen.IRandomFactory#getSecureRandom(java.lang.String * , java.lang.String) */ public Random getSecureRandom(String algorithm, String provider) throws NoSuchAlgorithmException, NoSuchProviderException { return initSecureRandom(algorithm, provider); } }