Source for gnu.java.security.jce.prng.SecureRandomAdapter

   1: /* SecureRandomAdapter.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.java.security.jce.prng;
  40: 
  41: import gnu.java.security.action.GetSecurityPropertyAction;
  42: import gnu.classpath.SystemProperties;
  43: import gnu.java.security.prng.LimitReachedException;
  44: import gnu.java.security.prng.MDGenerator;
  45: 
  46: import java.security.AccessController;
  47: import java.security.SecureRandom;
  48: import java.security.SecureRandomSpi;
  49: 
  50: import java.util.Collections;
  51: import java.util.logging.Level;
  52: import java.util.logging.Logger;
  53: 
  54: import java.io.InputStream;
  55: import java.io.IOException;
  56: 
  57: import java.net.MalformedURLException;
  58: import java.net.URL;
  59: 
  60: /**
  61:  * <p>The implementation of a generic {@link java.security.SecureRandom} adapter
  62:  * class to wrap gnu.crypto prng instances based on Message Digest algorithms.</p>
  63:  *
  64:  * <p>This class defines the <i>Service Provider Interface</i> (<b>SPI</b>) for
  65:  * the {@link java.security.SecureRandom} class, which provides the
  66:  * functionality of a cryptographically strong pseudo-random number generator.</p>
  67:  *
  68:  * <p>All the abstract methods in the {@link SecureRandomSpi} class are
  69:  * implemented by this class and all its sub-classes.</p>
  70:  */
  71: public abstract class SecureRandomAdapter
  72:   extends SecureRandomSpi
  73: {
  74: 
  75:   private boolean isSeeded = false;
  76: 
  77:   /** Our underlying prng instance. */
  78:   private MDGenerator adaptee = new MDGenerator();
  79: 
  80:   /** The name of the message digest algorithm used by the adaptee. */
  81:   private String mdName;
  82: 
  83:   private static final Logger logger =
  84:     Logger.getLogger(SecureRandom.class.getName());
  85: 
  86:   private static final String SECURERANDOM_SOURCE = "securerandom.source";
  87:   private static final String JAVA_SECURITY_EGD = "java.security.egd";
  88: 
  89:   /**
  90:    * <p>Trivial protected constructor.</p>
  91:    *
  92:    * @param mdName the canonical name of the underlying hash algorithm.
  93:    */
  94:   protected SecureRandomAdapter(String mdName)
  95:   {
  96:     super();
  97: 
  98:     this.mdName = mdName;
  99:     adaptee.init (Collections.singletonMap (MDGenerator.MD_NAME, mdName));
 100:   }
 101: 
 102:   public static final byte[] getSeed(int numBytes)
 103:   {
 104:     URL sourceUrl = null;
 105:     String urlStr = null;
 106: 
 107:     byte[] buffer = new byte[numBytes];
 108: 
 109:     GetSecurityPropertyAction action =
 110:       new GetSecurityPropertyAction(SECURERANDOM_SOURCE);
 111:     try
 112:       {
 113:         urlStr = (String) AccessController.doPrivileged(action);
 114:         if (urlStr != null)
 115:           sourceUrl = new URL(urlStr);
 116:       }
 117:     catch (MalformedURLException ignored)
 118:       {
 119:         logger.log(Level.WARNING,
 120:                    SECURERANDOM_SOURCE + " property is malformed: {0}",
 121:                    urlStr);
 122:       }
 123: 
 124:     if (sourceUrl == null)
 125:       {
 126:         try
 127:           {
 128:             urlStr = SystemProperties.getProperty(JAVA_SECURITY_EGD);
 129:             if (urlStr != null)
 130:               sourceUrl = new URL(urlStr);
 131:           }
 132:         catch (MalformedURLException mue)
 133:           {
 134:             logger.log(Level.WARNING,
 135:                        JAVA_SECURITY_EGD + " property is malformed: {0}",
 136:                        urlStr);
 137:           }
 138:       }
 139: 
 140:     if (sourceUrl != null)
 141:       {
 142:         try
 143:           {
 144:             InputStream in = sourceUrl.openStream();
 145:             in.read(buffer);
 146:             return buffer;
 147:           }
 148:         catch (IOException ioe)
 149:           {
 150:             logger.log(Level.FINE, "error reading random bytes", ioe);
 151:           }
 152:       }
 153: 
 154:     // If we get here, we did not get any seed from a property URL.
 155:     VMSecureRandom.generateSeed(buffer, 0, buffer.length);
 156:     return buffer;
 157:   }
 158: 
 159:   public byte[] engineGenerateSeed(int numBytes)
 160:   {
 161:     return getSeed(numBytes);
 162:   }
 163: 
 164:   public void engineNextBytes(byte[] bytes)
 165:   {
 166:     if (!isSeeded)
 167:       {
 168:         engineSetSeed(engineGenerateSeed(32));
 169:       }
 170:     try
 171:       {
 172:         adaptee.nextBytes(bytes, 0, bytes.length);
 173:       }
 174:     catch (LimitReachedException ignored)
 175:       {
 176:       }
 177:   }
 178: 
 179:   public void engineSetSeed(byte[] seed)
 180:   {
 181:     adaptee.addRandomBytes (seed);
 182:     isSeeded = true;
 183:   }
 184: }