1 /* PRNGFactory.java -- 2 Copyright (C) 2001, 2002, 2003, 2006 Free Software Foundation, Inc. 3 4 This file is a part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2 of the License, or (at 9 your option) any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; if not, write to the Free Software 18 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 19 USA 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package gnu.javax.crypto.prng; 40 41 import gnu.java.security.Registry; 42 import gnu.java.security.prng.IRandom; 43 import gnu.javax.crypto.mac.HMacFactory; 44 import gnu.javax.crypto.mac.IMac; 45 import gnu.javax.crypto.mac.MacFactory; 46 47 import java.util.Collections; 48 import java.util.HashSet; 49 import java.util.Iterator; 50 import java.util.Set; 51 52 /** 53 * A Factory to instantiate pseudo random number generators. 54 */ 55 public class PRNGFactory 56 implements Registry 57 { 58 /** Trivial constructor to enforce <i>Singleton</i> pattern. */ PRNGFactory()59 private PRNGFactory() 60 { 61 } 62 63 /** 64 * Returns an instance of a padding algorithm given its name. 65 * 66 * @param prng the case-insensitive name of the PRNG. 67 * @return an instance of the pseudo-random number generator. 68 * @exception InternalError if the implementation does not pass its self- 69 * test. 70 */ getInstance(String prng)71 public static IRandom getInstance(String prng) 72 { 73 if (prng == null) 74 return null; 75 prng = prng.trim(); 76 IRandom result = null; 77 if (prng.equalsIgnoreCase(ARCFOUR_PRNG) || prng.equalsIgnoreCase(RC4_PRNG)) 78 result = new ARCFour(); 79 else if (prng.equalsIgnoreCase(ICM_PRNG)) 80 result = new ICMGenerator(); 81 else if (prng.equalsIgnoreCase(UMAC_PRNG)) 82 result = new UMacGenerator(); 83 else if (prng.toLowerCase().startsWith(PBKDF2_PRNG_PREFIX)) 84 { 85 String macName = prng.substring(PBKDF2_PRNG_PREFIX.length()); 86 IMac mac = MacFactory.getInstance(macName); 87 if (mac == null) 88 return null; 89 result = new PBKDF2(mac); 90 } 91 92 if (result != null) 93 return result; 94 95 return gnu.java.security.prng.PRNGFactory.getInstance(prng); 96 } 97 98 /** 99 * Returns a {@link Set} of names of padding algorithms supported by this 100 * <i>Factory</i>. 101 * 102 * @return a {@link Set} of pseudo-random number generator algorithm names 103 * (Strings). 104 */ getNames()105 public static Set getNames() 106 { 107 HashSet hs = new HashSet(gnu.java.security.prng.PRNGFactory.getNames()); 108 hs.add(ICM_PRNG); 109 hs.add(UMAC_PRNG); 110 // add all hmac implementations as candidate PBKDF2 ones too 111 for (Iterator it = HMacFactory.getNames().iterator(); it.hasNext();) 112 hs.add(PBKDF2_PRNG_PREFIX + ((String) it.next())); 113 return Collections.unmodifiableSet(hs); 114 } 115 } 116