001 /* SignedObject.java --- Signed Object Class
002 Copyright (C) 1999, 2003, Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038 package java.security;
039
040 import java.io.ByteArrayInputStream;
041 import java.io.ByteArrayOutputStream;
042 import java.io.IOException;
043 import java.io.ObjectInput;
044 import java.io.ObjectInputStream;
045 import java.io.ObjectOutputStream;
046 import java.io.Serializable;
047
048 /**
049 * <code>SignedObject</code> is used for storing runtime objects whose
050 * integrity cannot be compromised without being detected.
051 *
052 * <p><code>SignedObject</code> contains a {@link Serializable} object which is
053 * yet to be signed and a digital signature of that object.</p>
054 *
055 * <p>The signed copy is a "deep copy" (in serialized form) of an original
056 * object. Any changes to that original instance are not reflected in the
057 * enclosed copy inside this <code>SignedObject</code>.</p>
058 *
059 * <p>Several things to note are that, first there is no need to initialize the
060 * signature engine as this class will handle that automatically. Second,
061 * verification will only succeed if the public key corresponds to the private
062 * key used to generate the digital signature inside this
063 * <code>SignedObject</code>.</p>
064 *
065 * <p>For fexibility, the signature engine can be specified in the constructor
066 * or the <code>verify()</code> method. Programmers wishing to verify
067 * <code>SignedObject</code>s should be aware of the {@link Signature} engine
068 * they use. A malicious or flawed {@link Signature} implementation may always
069 * return true on verification thus circumventing the intended secrity check
070 * provided by the <code>SignedObject</code>.</p>
071 *
072 * <p>The GNU security provider offers an implementation of the standard NIST
073 * DSA which uses "DSA" and "SHA-1". It can be specified by "SHA/DSA",
074 * "SHA-1/DSA" or its OID. If the RSA signature algorithm is provided then it
075 * could be "MD2/RSA". "MD5/RSA", or "SHA-1/RSA". The algorithm must be
076 * specified because there is no default.</p>
077 *
078 * @author Mark Benvenuto (ivymccough@worldnet.att.net)
079 * @since 1.2
080 * @see Signature
081 */
082 public final class SignedObject implements Serializable
083 {
084 private static final long serialVersionUID = 720502720485447167L;
085
086 /** @serial */
087 private byte[] content;
088 /** @serial */
089 private byte[] signature;
090 /** @serial */
091 private String thealgorithm;
092
093 /**
094 * Constructs a new instance of <code>SignedObject</code> from a
095 * {@link Serializable} object. The object is signed with a designated
096 * private key and a signature engine.
097 *
098 * @param object
099 * 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 }