1 /*
2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javax.crypto;
27
28 import java.io.*;
29
30 /**
31 * A CipherOutputStream is composed of an OutputStream and a Cipher so
32 * that write() methods first process the data before writing them out
33 * to the underlying OutputStream. The cipher must be fully
34 * initialized before being used by a CipherOutputStream.
35 *
36 * <p> For example, if the cipher is initialized for encryption, the
37 * CipherOutputStream will attempt to encrypt data before writing out the
38 * encrypted data.
39 *
40 * <p> This class adheres strictly to the semantics, especially the
41 * failure semantics, of its ancestor classes
42 * java.io.OutputStream and java.io.FilterOutputStream. This class
43 * has exactly those methods specified in its ancestor classes, and
44 * overrides them all. Moreover, this class catches all exceptions
45 * that are not thrown by its ancestor classes.
46 *
47 * <p> It is crucial for a programmer using this class not to use
48 * methods that are not defined or overriden in this class (such as a
49 * new method or constructor that is later added to one of the super
50 * classes), because the design and implementation of those methods
51 * are unlikely to have considered security impact with regard to
52 * CipherOutputStream.
53 *
54 * @author Li Gong
55 * @see java.io.OutputStream
56 * @see java.io.FilterOutputStream
57 * @see javax.crypto.Cipher
58 * @see javax.crypto.CipherInputStream
59 *
60 * @since 1.4
61 */
62
63 public class CipherOutputStream extends FilterOutputStream {
64
65 // the cipher engine to use to process stream data
66 private Cipher cipher;
67
68 // the underlying output stream
69 private OutputStream output;
70
71 /* the buffer holding one byte of incoming data */
72 private byte[] ibuffer = new byte[1];
73
74 // the buffer holding data ready to be written out
75 private byte[] obuffer;
76
77 // stream status
78 private boolean closed = false;
79
80 /**
81 *
82 * Constructs a CipherOutputStream from an OutputStream and a
83 * Cipher.
84 * <br>Note: if the specified output stream or cipher is
85 * null, a NullPointerException may be thrown later when
86 * they are used.
87 *
88 * @param os the OutputStream object
89 * @param c an initialized Cipher object
90 */
91 public CipherOutputStream(OutputStream os, Cipher c) {
92 super(os);
93 output = os;
94 cipher = c;
95 };
96
97 /**
98 * Constructs a CipherOutputStream from an OutputStream without
99 * specifying a Cipher. This has the effect of constructing a
100 * CipherOutputStream using a NullCipher.
101 * <br>Note: if the specified output stream is null, a
102 * NullPointerException may be thrown later when it is used.
103 *
104 * @param os the OutputStream object
105 */
106 protected CipherOutputStream(OutputStream os) {
107 super(os);
108 output = os;
109 cipher = new NullCipher();
110 }
111
112 /**
113 * Writes the specified byte to this output stream.
114 *
115 * @param b the <code>byte</code>.
116 * @exception IOException if an I/O error occurs.
117 */
118 public void write(int b) throws IOException {
119 ibuffer[0] = (byte) b;
120 obuffer = cipher.update(ibuffer, 0, 1);
121 if (obuffer != null) {
122 output.write(obuffer);
123 obuffer = null;
124 }
125 };
126
127 /**
128 * Writes <code>b.length</code> bytes from the specified byte array
129 * to this output stream.
130 * <p>
131 * The <code>write</code> method of
132 * <code>CipherOutputStream</code> calls the <code>write</code>
133 * method of three arguments with the three arguments
134 * <code>b</code>, <code>0</code>, and <code>b.length</code>.
135 *
136 * @param b the data.
137 * @exception NullPointerException if <code>b</code> is null.
138 * @exception IOException if an I/O error occurs.
139 * @see javax.crypto.CipherOutputStream#write(byte[], int, int)
140 */
141 public void write(byte b[]) throws IOException {
142 write(b, 0, b.length);
143 }
144
145 /**
146 * Writes <code>len</code> bytes from the specified byte array
147 * starting at offset <code>off</code> to this output stream.
148 *
149 * @param b the data.
150 * @param off the start offset in the data.
151 * @param len the number of bytes to write.
152 * @exception IOException if an I/O error occurs.
153 */
154 public void write(byte b[], int off, int len) throws IOException {
155 obuffer = cipher.update(b, off, len);
156 if (obuffer != null) {
157 output.write(obuffer);
158 obuffer = null;
159 }
160 }
161
162 /**
163 * Flushes this output stream by forcing any buffered output bytes
164 * that have already been processed by the encapsulated cipher object
165 * to be written out.
166 *
167 * <p>Any bytes buffered by the encapsulated cipher
168 * and waiting to be processed by it will not be written out. For example,
169 * if the encapsulated cipher is a block cipher, and the total number of
170 * bytes written using one of the <code>write</code> methods is less than
171 * the cipher's block size, no bytes will be written out.
172 *
173 * @exception IOException if an I/O error occurs.
174 */
175 public void flush() throws IOException {
176 if (obuffer != null) {
177 output.write(obuffer);
178 obuffer = null;
179 }
180 output.flush();
181 }
182
183 /**
184 * Closes this output stream and releases any system resources
185 * associated with this stream.
186 * <p>
187 * This method invokes the <code>doFinal</code> method of the encapsulated
188 * cipher object, which causes any bytes buffered by the encapsulated
189 * cipher to be processed. The result is written out by calling the
190 * <code>flush</code> method of this output stream.
191 * <p>
192 * This method resets the encapsulated cipher object to its initial state
193 * and calls the <code>close</code> method of the underlying output
194 * stream.
195 *
196 * @exception IOException if an I/O error occurs.
197 */
198 public void close() throws IOException {
199 if (closed) {
200 return;
201 }
202
203 closed = true;
204 try {
205 obuffer = cipher.doFinal();
206 } catch (IllegalBlockSizeException | BadPaddingException e) {
207 obuffer = null;
208 }
209 try {
210 flush();
211 } catch (IOException ignored) {}
212 out.close();
213 }
214 }