Source for gnu.java.security.sig.BaseSignature

   1: /* BaseSignature.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.sig;
  40: 
  41: import gnu.java.security.hash.IMessageDigest;
  42: import gnu.java.security.prng.IRandom;
  43: import gnu.java.security.prng.LimitReachedException;
  44: import gnu.java.security.util.PRNG;
  45: 
  46: import java.security.PrivateKey;
  47: import java.security.PublicKey;
  48: import java.util.Map;
  49: import java.util.Random;
  50: 
  51: /**
  52:  * A base abstract class to facilitate implementations of concrete Signatures.
  53:  */
  54: public abstract class BaseSignature
  55:     implements ISignature
  56: {
  57:   /** The canonical name of this signature scheme. */
  58:   protected String schemeName;
  59: 
  60:   /** The underlying message digest instance for this signature scheme. */
  61:   protected IMessageDigest md;
  62: 
  63:   /** The public key to use when verifying signatures. */
  64:   protected PublicKey publicKey;
  65: 
  66:   /** The private key to use when generating signatures (signing). */
  67:   protected PrivateKey privateKey;
  68: 
  69:   /** The optional {@link Random} instance to use. */
  70:   private Random rnd;
  71: 
  72:   /** The optional {@link IRandom} instance to use. */
  73:   private IRandom irnd;
  74: 
  75:   /** Our default source of randomness. */
  76:   private PRNG prng = null;
  77: 
  78:   /**
  79:    * Trivial constructor.
  80:    *
  81:    * @param schemeName the name of this signature scheme.
  82:    * @param md the underlying instance of the message digest algorithm.
  83:    * @throws IllegalArgumentException if the designated hash instance is
  84:    *           <code>null</code>.
  85:    */
  86:   protected BaseSignature(String schemeName, IMessageDigest md)
  87:   {
  88:     super();
  89: 
  90:     this.schemeName = schemeName;
  91:     if (md == null)
  92:       throw new IllegalArgumentException("Message digest MUST NOT be null");
  93: 
  94:     this.md = md;
  95:   }
  96: 
  97:   public String name()
  98:   {
  99:     return schemeName + "-" + md.name();
 100:   }
 101: 
 102:   public void setupVerify(Map attributes) throws IllegalArgumentException
 103:   {
 104:     setup(attributes);
 105:     // do we have a public key?
 106:     PublicKey key = (PublicKey) attributes.get(VERIFIER_KEY);
 107:     if (key != null)
 108:       setupForVerification(key);
 109:   }
 110: 
 111:   public void setupSign(Map attributes) throws IllegalArgumentException
 112:   {
 113:     setup(attributes);
 114:     // do we have a private key?
 115:     PrivateKey key = (PrivateKey) attributes.get(SIGNER_KEY);
 116:     if (key != null)
 117:       setupForSigning(key);
 118:   }
 119: 
 120:   public void update(byte b)
 121:   {
 122:     if (md == null)
 123:       throw new IllegalStateException();
 124: 
 125:     md.update(b);
 126:   }
 127: 
 128:   public void update(byte[] b, int off, int len)
 129:   {
 130:     if (md == null)
 131:       throw new IllegalStateException();
 132: 
 133:     md.update(b, off, len);
 134:   }
 135: 
 136:   public Object sign()
 137:   {
 138:     if (md == null || privateKey == null)
 139:       throw new IllegalStateException();
 140: 
 141:     return generateSignature();
 142:   }
 143: 
 144:   public boolean verify(Object sig)
 145:   {
 146:     if (md == null || publicKey == null)
 147:       throw new IllegalStateException();
 148: 
 149:     return verifySignature(sig);
 150:   }
 151: 
 152:   public abstract Object clone();
 153: 
 154:   protected abstract void setupForVerification(PublicKey key)
 155:       throws IllegalArgumentException;
 156: 
 157:   protected abstract void setupForSigning(PrivateKey key)
 158:       throws IllegalArgumentException;
 159: 
 160:   protected abstract Object generateSignature() throws IllegalStateException;
 161: 
 162:   protected abstract boolean verifySignature(Object signature)
 163:       throws IllegalStateException;
 164: 
 165:   /** Initialises the internal fields of this instance. */
 166:   protected void init()
 167:   {
 168:     md.reset();
 169:     rnd = null;
 170:     irnd = null;
 171:     publicKey = null;
 172:     privateKey = null;
 173:   }
 174: 
 175:   /**
 176:    * Fills the designated byte array with random data.
 177:    *
 178:    * @param buffer the byte array to fill with random data.
 179:    */
 180:   protected void nextRandomBytes(byte[] buffer)
 181:   {
 182:     if (rnd != null)
 183:       rnd.nextBytes(buffer);
 184:     else if (irnd != null)
 185:       try
 186:         {
 187:           irnd.nextBytes(buffer, 0, buffer.length);
 188:         }
 189:       catch (IllegalStateException x)
 190:         {
 191:           throw new RuntimeException("nextRandomBytes(): " + x);
 192:         }
 193:       catch (LimitReachedException x)
 194:         {
 195:           throw new RuntimeException("nextRandomBytes(): " + x);
 196:         }
 197:     else
 198:       getDefaultPRNG().nextBytes(buffer);
 199:   }
 200: 
 201:   private void setup(Map attributes)
 202:   {
 203:     init();
 204:     // do we have a Random or SecureRandom, or should we use our own?
 205:     Object obj = attributes.get(SOURCE_OF_RANDOMNESS);
 206:     if (obj instanceof Random)
 207:       rnd = (Random) obj;
 208:     else if (obj instanceof IRandom)
 209:       irnd = (IRandom) obj;
 210:   }
 211: 
 212:   private PRNG getDefaultPRNG()
 213:   {
 214:     if (prng == null)
 215:       prng = PRNG.getInstance();
 216: 
 217:     return prng;
 218:   }
 219: }