libjava/classpath/java/security/SignedObject.java

   1 /* SignedObject.java --- Signed Object Class
   2    Copyright (C) 1999, 2003, Free Software Foundation, Inc.
   3
   4 This file is 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, or (at your option)
   9 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; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 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 package java.security;
  39
  40 import java.io.ByteArrayInputStream;
  41 import java.io.ByteArrayOutputStream;
  42 import java.io.IOException;
  43 import java.io.ObjectInput;
  44 import java.io.ObjectInputStream;
  45 import java.io.ObjectOutputStream;
  46 import java.io.Serializable;
  47
  48 /**
  49  * <code>SignedObject</code> is used for storing runtime objects whose
  50  * integrity cannot be compromised without being detected.
  51  *
  52  * <p><code>SignedObject</code> contains a {@link Serializable} object which is
  53  * yet to be signed and a digital signature of that object.</p>
  54  *
  55  * <p>The signed copy is a "deep copy" (in serialized form) of an original
  56  * object. Any changes to that original instance are not reflected in the
  57  * enclosed copy inside this <code>SignedObject</code>.</p>
  58  *
  59  * <p>Several things to note are that, first there is no need to initialize the
  60  * signature engine as this class will handle that automatically. Second,
  61  * verification will only succeed if the public key corresponds to the private
  62  * key used to generate the digital signature inside this
  63  * <code>SignedObject</code>.</p>
  64  *
  65  * <p>For fexibility, the signature engine can be specified in the constructor
  66  * or the <code>verify()</code> method. Programmers wishing to verify
  67  * <code>SignedObject</code>s should be aware of the {@link Signature} engine
  68  * they use. A malicious or flawed {@link Signature} implementation may always
  69  * return true on verification thus circumventing the intended secrity check
  70  * provided by the <code>SignedObject</code>.</p>
  71  *
  72  * <p>The GNU security provider offers an implementation of the standard NIST
  73  * DSA which uses "DSA" and "SHA-1". It can be specified by "SHA/DSA",
  74  * "SHA-1/DSA" or its OID. If the RSA signature algorithm is provided then it
  75  * could be "MD2/RSA". "MD5/RSA", or "SHA-1/RSA". The algorithm must be
  76  * specified because there is no default.</p>
  77  *
  78  * @author Mark Benvenuto (ivymccough@worldnet.att.net)
  79  * @since 1.2
  80  * @see Signature
  81  */
  82 public final class SignedObject implements Serializable
  83 {
  84   private static final long serialVersionUID = 720502720485447167L;
  85
  86   /** @serial */
  87   private byte[] content;
  88   /** @serial */
  89   private byte[] signature;
  90   /** @serial */
  91   private String thealgorithm;
  92
  93   /**
  94    * Constructs a new instance of <code>SignedObject</code> from a
  95    * {@link Serializable} object. The object is signed with a designated
  96    * private key and a signature engine.
  97    *
  98    * @param object
  99    *          the object to sign.
 100    * @param signingKey
 101    *          the key to use.
 102    * @param signingEngine
 103    *          the signature engine to use.
 104    * @throws IOException
 105    *           if a serialization error occurred.
 106    * @throws InvalidKeyException
 107    *           if the key is invalid.
 108    * @throws SignatureException
 109    *           if a signing error occurs.
 110    */
 111   public SignedObject(Serializable object, PrivateKey signingKey,
 112                       Signature signingEngine)
 113     throws IOException, InvalidKeyException, SignatureException
 114   {
 115     thealgorithm = signingEngine.getAlgorithm();
 116
 117     ByteArrayOutputStream ostream = new ByteArrayOutputStream();
 118     ObjectOutputStream p = new ObjectOutputStream(ostream);
 119     p.writeObject(object);
 120     p.flush();
 121     p.close();
 122
 123     content = ostream.toByteArray();
 124
 125     signingEngine.initSign(signingKey);
 126     signingEngine.update(content);
 127     signature = signingEngine.sign();
 128   }
 129
 130   /**
 131    * Returns the encapsulated object. The object is de-serialized before being
 132    * returned.
 133    *
 134    * @return the encapsulated object.
 135    * @throws IOException
 136    *           if a de-serialization error occurs.
 137    * @throws ClassNotFoundException
 138    *           if the encapsulated object's class was not found.
 139    */
 140   public Object getObject() throws IOException, ClassNotFoundException
 141   {
 142     ByteArrayInputStream bais = new ByteArrayInputStream(content);
 143     ObjectInput oi = new ObjectInputStream(bais);
 144     Object obj = oi.readObject();
 145     oi.close();
 146     bais.close();
 147
 148     return obj;
 149   }
 150
 151   /**
 152    * Returns the signature bytes of the encapsulated object.
 153    *
 154    * @return the signature bytes of the encapsulated object.
 155    */
 156   public byte[] getSignature()
 157   {
 158     return (byte[]) signature.clone();
 159
 160   }
 161
 162   /**
 163    * Returns the name of the signature algorithm.
 164    *
 165    * @return the name of the signature algorithm.
 166    */
 167   public String getAlgorithm()
 168   {
 169     return thealgorithm;
 170   }
 171
 172   /**
 173    * Verifies the encapsulated digital signature by checking that it was
 174    * generated by the owner of a designated public key.
 175    *
 176    * @param verificationKey
 177    *          the public key to use.
 178    * @param verificationEngine
 179    *          the signature engine to use.
 180    * @return <code>true</code> if signature is correct, <code>false</code>
 181    *         otherwise.
 182    * @throws InvalidKeyException
 183    *           if the key is invalid.
 184    * @throws SignatureException
 185    *           if verification fails.
 186    */
 187   public boolean verify(PublicKey verificationKey, Signature verificationEngine)
 188     throws InvalidKeyException, SignatureException
 189   {
 190     verificationEngine.initVerify(verificationKey);
 191     verificationEngine.update(content);
 192     return verificationEngine.verify(signature);
 193   }
 194
 195   /** Called to restore the state of the SignedObject from a stream. */
 196   private void readObject(ObjectInputStream s)
 197     throws IOException, ClassNotFoundException
 198   {
 199     s.defaultReadObject();
 200     content = (byte[]) content.clone();
 201     signature = (byte[]) signature.clone();
 202   }
 203 }