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 }