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1: /* UMacRandomSpi.java -- 2: Copyright (C) 2001, 2002, 2006, 2010 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 = Configuration.DEBUG ? 61: Logger.getLogger(UMacRandomSpi.class.getName()) : null; 62: 63: /** Class-wide prng to generate random material for the underlying prng. */ 64: private static final UMacGenerator prng; // blank final 65: static 66: { 67: prng = new UMacGenerator(); 68: resetLocalPRNG(); 69: } 70: // error messages 71: private static final String MSG = "Exception while setting up a " 72: + Registry.UMAC_PRNG + " SPI: "; 73: private static final String RETRY = "Retry..."; 74: /** Our underlying prng instance. */ 75: private UMacGenerator adaptee = new UMacGenerator(); 76: 77: // default 0-arguments constructor 78: 79: private static void resetLocalPRNG() 80: { 81: HashMap attributes = new HashMap(); 82: attributes.put(UMacGenerator.CIPHER, Registry.AES_CIPHER); 83: byte[] key = new byte[128 / 8]; // AES default key size 84: Random rand = new Random(System.currentTimeMillis()); 85: rand.nextBytes(key); 86: attributes.put(IBlockCipher.KEY_MATERIAL, key); 87: int index = rand.nextInt() & 0xFF; 88: attributes.put(UMacGenerator.INDEX, Integer.valueOf(index)); 89: prng.setup(attributes); 90: } 91: 92: public byte[] engineGenerateSeed(int numBytes) 93: { 94: return SecureRandomAdapter.getSeed(numBytes); 95: } 96: 97: public void engineNextBytes(byte[] bytes) 98: { 99: if (! adaptee.isInitialised()) 100: engineSetSeed(engineGenerateSeed(32)); 101: while (true) 102: { 103: try 104: { 105: adaptee.nextBytes(bytes, 0, bytes.length); 106: break; 107: } 108: catch (LimitReachedException x) 109: { // reseed the generator 110: resetLocalPRNG(); 111: } 112: } 113: } 114: 115: public void engineSetSeed(byte[] seed) 116: { 117: // compute the total number of random bytes required to setup adaptee 118: int materialLength = 0; 119: materialLength += 16; // key material size 120: materialLength++; // index size 121: byte[] material = new byte[materialLength]; 122: // use as much as possible bytes from the seed 123: int materialOffset = 0; 124: int materialLeft = material.length; 125: if (seed.length > 0) 126: { // copy some bytes into key and update indices 127: int lenToCopy = Math.min(materialLength, seed.length); 128: System.arraycopy(seed, 0, material, 0, lenToCopy); 129: materialOffset += lenToCopy; 130: materialLeft -= lenToCopy; 131: } 132: if (materialOffset > 0) // generate the rest 133: { 134: while (true) 135: { 136: try 137: { 138: prng.nextBytes(material, materialOffset, materialLeft); 139: break; 140: } 141: catch (IllegalStateException x) // should not happen 142: { 143: throw new InternalError(MSG + String.valueOf(x)); 144: } 145: catch (LimitReachedException x) 146: { 147: if (Configuration.DEBUG) 148: { 149: log.fine(MSG + String.valueOf(x)); 150: log.fine(RETRY); 151: } 152: } 153: } 154: } 155: // setup the underlying adaptee instance 156: HashMap attributes = new HashMap(); 157: // use AES cipher with 128-bit block size 158: attributes.put(UMacGenerator.CIPHER, Registry.AES_CIPHER); 159: // specify the key 160: byte[] key = new byte[16]; 161: System.arraycopy(material, 0, key, 0, 16); 162: attributes.put(IBlockCipher.KEY_MATERIAL, key); 163: // use a 1-byte index 164: attributes.put(UMacGenerator.INDEX, Integer.valueOf(material[16] & 0xFF)); 165: adaptee.init(attributes); 166: } 167: }