001 /* CipherInputStream.java -- Filters input through a cipher.
002 Copyright (C) 2004 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
039 package javax.crypto;
040
041 import gnu.classpath.Configuration;
042 import gnu.classpath.debug.Component;
043 import gnu.classpath.debug.SystemLogger;
044
045 import java.io.FilterInputStream;
046 import java.io.IOException;
047 import java.io.InputStream;
048
049 import java.util.logging.Logger;
050
051 /**
052 * This is an {@link java.io.InputStream} that filters its data
053 * through a {@link Cipher} before returning it. The <code>Cipher</code>
054 * argument must have been initialized before it is passed to the
055 * constructor.
056 *
057 * @author Casey Marshall (csm@gnu.org)
058 */
059 public class CipherInputStream extends FilterInputStream
060 {
061
062 // Constants and variables.
063 // ------------------------------------------------------------------------
064
065 private static final Logger logger = SystemLogger.SYSTEM;
066
067 /**
068 * The underlying {@link Cipher} instance.
069 */
070 private final Cipher cipher;
071
072 /**
073 * Data that has been transformed but not read.
074 */
075 private byte[] outBuffer;
076
077 /**
078 * The offset into {@link #outBuffer} where valid data starts.
079 */
080 private int outOffset;
081
082 /**
083 * We set this when the cipher block size is 1, meaning that we can
084 * transform any amount of data.
085 */
086 private final boolean isStream;
087
088 /**
089 * Whether or not we've reached the end of the stream.
090 */
091 private boolean eof;
092
093 // Constructors.
094 // ------------------------------------------------------------------------
095
096 /**
097 * Creates a new input stream with a source input stream and cipher.
098 *
099 * @param in The underlying input stream.
100 * @param cipher The cipher to filter data through.
101 */
102 public CipherInputStream(InputStream in, Cipher cipher)
103 {
104 super (in);
105 this.cipher = cipher;
106 isStream = cipher.getBlockSize () == 1;
107 eof = false;
108 if (Configuration.DEBUG)
109 logger.log (Component.CRYPTO, "I am born; cipher: {0}, stream? {1}",
110 new Object[] { cipher.getAlgorithm (),
111 Boolean.valueOf (isStream) });
112 }
113
114 /**
115 * Creates a new input stream without a cipher. This constructor is
116 * <code>protected</code> because this class does not work without an
117 * underlying cipher.
118 *
119 * @param in The underlying input stream.
120 */
121 protected CipherInputStream(InputStream in)
122 {
123 this (in, new NullCipher ());
124 }
125
126 // Instance methods overriding java.io.FilterInputStream.
127 // ------------------------------------------------------------------------
128
129 /**
130 * Returns the number of bytes available without blocking. The value
131 * returned is the number of bytes that have been processed by the
132 * cipher, and which are currently buffered by this class.
133 *
134 * @return The number of bytes immediately available.
135 * @throws java.io.IOException If an I/O exception occurs.
136 */
137 public int available() throws IOException
138 {
139 if (isStream)
140 return super.available();
141 if (outBuffer == null || outOffset >= outBuffer.length)
142 nextBlock ();
143 return outBuffer.length - outOffset;
144 }
145
146 /**
147 * Close this input stream. This method merely calls the {@link
148 * java.io.InputStream#close()} method of the underlying input stream.
149 *
150 * @throws java.io.IOException If an I/O exception occurs.
151 */
152 public synchronized void close() throws IOException
153 {
154 super.close();
155 }
156
157 /**
158 * Read a single byte from this input stream; returns -1 on the
159 * end-of-file.
160 *
161 * @return The byte read, or -1 if there are no more bytes.
162 * @throws java.io.IOExcpetion If an I/O exception occurs.
163 */
164 public synchronized int read() throws IOException
165 {
166 if (isStream)
167 {
168 byte[] buf = new byte[1];
169 int in = super.read();
170 if (in == -1)
171 return -1;
172 buf[0] = (byte) in;
173 try
174 {
175 cipher.update(buf, 0, 1, buf, 0);
176 }
177 catch (ShortBufferException shouldNotHappen)
178 {
179 throw new IOException(shouldNotHappen.getMessage());
180 }
181 return buf[0] & 0xFF;
182 }
183
184 if (outBuffer == null || outOffset == outBuffer.length)
185 {
186 if (eof)
187 return -1;
188 nextBlock ();
189 }
190 return outBuffer [outOffset++] & 0xFF;
191 }
192
193 /**
194 * Read bytes into an array, returning the number of bytes read or -1
195 * on the end-of-file.
196 *
197 * @param buf The byte array to read into.
198 * @param off The offset in <code>buf</code> to start.
199 * @param len The maximum number of bytes to read.
200 * @return The number of bytes read, or -1 on the end-of-file.
201 * @throws java.io.IOException If an I/O exception occurs.
202 */
203 public synchronized int read(byte[] buf, int off, int len)
204 throws IOException
205 {
206 // CipherInputStream has this wierd implementation where if
207 // the buffer is null, this call is the same as `skip'.
208 if (buf == null)
209 return (int) skip (len);
210
211 if (isStream)
212 {
213 len = super.read(buf, off, len);
214 if (len > 0)
215 {
216 try
217 {
218 cipher.update(buf, off, len, buf, off);
219 }
220 catch (ShortBufferException shouldNotHappen)
221 {
222 IOException ioe = new IOException ("Short buffer for stream cipher -- this should not happen");
223 ioe.initCause (shouldNotHappen);
224 throw ioe;
225 }
226 }
227 return len;
228 }
229
230 int count = 0;
231 while (count < len)
232 {
233 if (outBuffer == null || outOffset >= outBuffer.length)
234 {
235 if (eof)
236 {
237 if (count == 0)
238 count = -1;
239 break;
240 }
241 nextBlock();
242 }
243 int l = Math.min (outBuffer.length - outOffset, len - count);
244 System.arraycopy (outBuffer, outOffset, buf, count+off, l);
245 count += l;
246 outOffset += l;
247 }
248 return count;
249 }
250
251 /**
252 * Read bytes into an array, returning the number of bytes read or -1
253 * on the end-of-file.
254 *
255 * @param buf The byte arry to read into.
256 * @return The number of bytes read, or -1 on the end-of-file.
257 * @throws java.io.IOException If an I/O exception occurs.
258 */
259 public int read(byte[] buf) throws IOException
260 {
261 return read(buf, 0, buf.length);
262 }
263
264 /**
265 * Skip a number of bytes. This class only supports skipping as many
266 * bytes as are returned by {@link #available()}, which is the number
267 * of transformed bytes currently in this class's internal buffer.
268 *
269 * @param bytes The number of bytes to skip.
270 * @return The number of bytes skipped.
271 */
272 public long skip(long bytes) throws IOException
273 {
274 if (isStream)
275 {
276 return super.skip(bytes);
277 }
278 long ret = 0;
279 if (bytes > 0 && outBuffer != null && outOffset >= outBuffer.length)
280 {
281 ret = outBuffer.length - outOffset;
282 outOffset = outBuffer.length;
283 }
284 return ret;
285 }
286
287 /**
288 * Returns whether or not this input stream supports the {@link
289 * #mark(long)} and {@link #reset()} methods; this input stream does
290 * not, however, and invariably returns <code>false</code>.
291 *
292 * @return <code>false</code>
293 */
294 public boolean markSupported()
295 {
296 return false;
297 }
298
299 /**
300 * Set the mark. This method is unsupported and is empty.
301 *
302 * @param mark Is ignored.
303 */
304 public void mark(int mark)
305 {
306 }
307
308 /**
309 * Reset to the mark. This method is unsupported and is empty.
310 */
311 public void reset() throws IOException
312 {
313 throw new IOException("reset not supported");
314 }
315
316 // Own methods.
317 // -------------------------------------------------------------------------
318
319 // FIXME: I don't fully understand how this class is supposed to work.
320
321 private void nextBlock() throws IOException
322 {
323 byte[] buf = new byte[cipher.getBlockSize ()];
324 if (Configuration.DEBUG)
325 logger.log (Component.CRYPTO, "getting a new data block");
326
327 try
328 {
329 outBuffer = null;
330 outOffset = 0;
331 while (outBuffer == null)
332 {
333 int l = in.read (buf);
334 if (Configuration.DEBUG)
335 logger.log (Component.CRYPTO, "we read {0} bytes",
336 Integer.valueOf (l));
337 if (l == -1)
338 {
339 outBuffer = cipher.doFinal ();
340 eof = true;
341 return;
342 }
343
344 outOffset = 0;
345 outBuffer = cipher.update (buf, 0, l);
346 }
347 }
348 catch (BadPaddingException bpe)
349 {
350 IOException ioe = new IOException ("bad padding");
351 ioe.initCause (bpe);
352 throw ioe;
353 }
354 catch (IllegalBlockSizeException ibse)
355 {
356 IOException ioe = new IOException ("illegal block size");
357 ioe.initCause (ibse);
358 throw ioe;
359 }
360 finally
361 {
362 if (Configuration.DEBUG)
363 logger.log (Component.CRYPTO,
364 "decrypted {0} bytes for reading",
365 Integer.valueOf (outBuffer.length));
366 }
367 }
368 }