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1: /* UMacRandomSpi.java -- 2: Copyright (C) 2001, 2002, 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.jce.prng; 40: 41: import gnu.java.security.Configuration; 42: import gnu.java.security.Registry; 43: import gnu.java.security.prng.LimitReachedException; 44: import gnu.java.security.jce.prng.SecureRandomAdapter; 45: import gnu.javax.crypto.cipher.IBlockCipher; 46: import gnu.javax.crypto.prng.UMacGenerator; 47: 48: import java.security.SecureRandomSpi; 49: import java.util.HashMap; 50: import java.util.Random; 51: import java.util.logging.Logger; 52: 53: /** 54: * An <em>Adapter</em> class around {@link UMacGenerator} to allow using this 55: * algorithm as a JCE {@link java.security.SecureRandom}. 56: */ 57: public class UMacRandomSpi 58: extends SecureRandomSpi 59: { 60: private static final Logger log = Logger.getLogger(UMacRandomSpi.class.getName()); 61: 62: /** Class-wide prng to generate random material for the underlying prng. */ 63: private static final UMacGenerator prng; // blank final 64: static 65: { 66: prng = new UMacGenerator(); 67: resetLocalPRNG(); 68: } 69: // error messages 70: private static final String MSG = "Exception while setting up a " 71: + Registry.UMAC_PRNG + " SPI: "; 72: private static final String RETRY = "Retry..."; 73: /** Our underlying prng instance. */ 74: private UMacGenerator adaptee = new UMacGenerator(); 75: 76: // default 0-arguments constructor 77: 78: private static void resetLocalPRNG() 79: { 80: HashMap attributes = new HashMap(); 81: attributes.put(UMacGenerator.CIPHER, Registry.AES_CIPHER); 82: byte[] key = new byte[128 / 8]; // AES default key size 83: Random rand = new Random(System.currentTimeMillis()); 84: rand.nextBytes(key); 85: attributes.put(IBlockCipher.KEY_MATERIAL, key); 86: int index = rand.nextInt() & 0xFF; 87: attributes.put(UMacGenerator.INDEX, Integer.valueOf(index)); 88: prng.setup(attributes); 89: } 90: 91: public byte[] engineGenerateSeed(int numBytes) 92: { 93: return SecureRandomAdapter.getSeed(numBytes); 94: } 95: 96: public void engineNextBytes(byte[] bytes) 97: { 98: if (! adaptee.isInitialised()) 99: engineSetSeed(engineGenerateSeed(32)); 100: while (true) 101: { 102: try 103: { 104: adaptee.nextBytes(bytes, 0, bytes.length); 105: break; 106: } 107: catch (LimitReachedException x) 108: { // reseed the generator 109: resetLocalPRNG(); 110: } 111: } 112: } 113: 114: public void engineSetSeed(byte[] seed) 115: { 116: // compute the total number of random bytes required to setup adaptee 117: int materialLength = 0; 118: materialLength += 16; // key material size 119: materialLength++; // index size 120: byte[] material = new byte[materialLength]; 121: // use as much as possible bytes from the seed 122: int materialOffset = 0; 123: int materialLeft = material.length; 124: if (seed.length > 0) 125: { // copy some bytes into key and update indices 126: int lenToCopy = Math.min(materialLength, seed.length); 127: System.arraycopy(seed, 0, material, 0, lenToCopy); 128: materialOffset += lenToCopy; 129: materialLeft -= lenToCopy; 130: } 131: if (materialOffset > 0) // generate the rest 132: { 133: while (true) 134: { 135: try 136: { 137: prng.nextBytes(material, materialOffset, materialLeft); 138: break; 139: } 140: catch (IllegalStateException x) // should not happen 141: { 142: throw new InternalError(MSG + String.valueOf(x)); 143: } 144: catch (LimitReachedException x) 145: { 146: if (Configuration.DEBUG) 147: { 148: log.fine(MSG + String.valueOf(x)); 149: log.fine(RETRY); 150: } 151: } 152: } 153: } 154: // setup the underlying adaptee instance 155: HashMap attributes = new HashMap(); 156: // use AES cipher with 128-bit block size 157: attributes.put(UMacGenerator.CIPHER, Registry.AES_CIPHER); 158: // specify the key 159: byte[] key = new byte[16]; 160: System.arraycopy(material, 0, key, 0, 16); 161: attributes.put(IBlockCipher.KEY_MATERIAL, key); 162: // use a 1-byte index 163: attributes.put(UMacGenerator.INDEX, Integer.valueOf(material[16] & 0xFF)); 164: adaptee.init(attributes); 165: } 166: }