1 /*
2 * Copyright (c) 1996, 2011, 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 java.security;
27
28 import java.util.*;
29 import java.lang.*;
30 import java.io.IOException;
31 import java.io.ByteArrayOutputStream;
32 import java.io.PrintStream;
33 import java.io.InputStream;
34 import java.io.ByteArrayInputStream;
35
36 import java.nio.ByteBuffer;
37
38 /**
39 * This MessageDigest class provides applications the functionality of a
40 * message digest algorithm, such as SHA-1 or SHA-256.
41 * Message digests are secure one-way hash functions that take arbitrary-sized
42 * data and output a fixed-length hash value.
43 *
44 * <p>A MessageDigest object starts out initialized. The data is
45 * processed through it using the {@link #update(byte) update}
46 * methods. At any point {@link #reset() reset} can be called
47 * to reset the digest. Once all the data to be updated has been
48 * updated, one of the {@link #digest() digest} methods should
49 * be called to complete the hash computation.
50 *
51 * <p>The <code>digest</code> method can be called once for a given number
52 * of updates. After <code>digest</code> has been called, the MessageDigest
53 * object is reset to its initialized state.
54 *
55 * <p>Implementations are free to implement the Cloneable interface.
56 * Client applications can test cloneability by attempting cloning
57 * and catching the CloneNotSupportedException: <p>
58 *
59 * <pre>
60 * MessageDigest md = MessageDigest.getInstance("SHA");
61 *
62 * try {
63 * md.update(toChapter1);
64 * MessageDigest tc1 = md.clone();
65 * byte[] toChapter1Digest = tc1.digest();
66 * md.update(toChapter2);
67 * ...etc.
68 * } catch (CloneNotSupportedException cnse) {
69 * throw new DigestException("couldn't make digest of partial content");
70 * }
71 * </pre>
72 *
73 * <p>Note that if a given implementation is not cloneable, it is
74 * still possible to compute intermediate digests by instantiating
75 * several instances, if the number of digests is known in advance.
76 *
77 * <p>Note that this class is abstract and extends from
78 * <code>MessageDigestSpi</code> for historical reasons.
79 * Application developers should only take notice of the methods defined in
80 * this <code>MessageDigest</code> class; all the methods in
81 * the superclass are intended for cryptographic service providers who wish to
82 * supply their own implementations of message digest algorithms.
83 *
84 * <p> Every implementation of the Java platform is required to support
85 * the following standard <code>MessageDigest</code> algorithms:
86 * <ul>
87 * <li><tt>MD5</tt></li>
88 * <li><tt>SHA-1</tt></li>
89 * <li><tt>SHA-256</tt></li>
90 * </ul>
91 * These algorithms are described in the <a href=
92 * "{@docRoot}/../technotes/guides/security/StandardNames.html#MessageDigest">
93 * MessageDigest section</a> of the
94 * Java Cryptography Architecture Standard Algorithm Name Documentation.
95 * Consult the release documentation for your implementation to see if any
96 * other algorithms are supported.
97 *
98 * @author Benjamin Renaud
99 *
100 * @see DigestInputStream
101 * @see DigestOutputStream
102 */
103
104 public abstract class MessageDigest extends MessageDigestSpi {
105
106 private String algorithm;
107
108 // The state of this digest
109 private static final int INITIAL = 0;
110 private static final int IN_PROGRESS = 1;
111 private int state = INITIAL;
112
113 // The provider
114 private Provider provider;
115
116 /**
117 * Creates a message digest with the specified algorithm name.
118 *
119 * @param algorithm the standard name of the digest algorithm.
120 * See the MessageDigest section in the <a href=
121 * "{@docRoot}/../technotes/guides/security/StandardNames.html#MessageDigest">
122 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
123 * for information about standard algorithm names.
124 */
125 protected MessageDigest(String algorithm) {
126 this.algorithm = algorithm;
127 }
128
129 /**
130 * Returns a MessageDigest object that implements the specified digest
131 * algorithm.
132 *
133 * <p> This method traverses the list of registered security Providers,
134 * starting with the most preferred Provider.
135 * A new MessageDigest object encapsulating the
136 * MessageDigestSpi implementation from the first
137 * Provider that supports the specified algorithm is returned.
138 *
139 * <p> Note that the list of registered providers may be retrieved via
140 * the {@link Security#getProviders() Security.getProviders()} method.
141 *
142 * @param algorithm the name of the algorithm requested.
143 * See the MessageDigest section in the <a href=
144 * "{@docRoot}/../technotes/guides/security/StandardNames.html#MessageDigest">
145 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
146 * for information about standard algorithm names.
147 *
148 * @return a Message Digest object that implements the specified algorithm.
149 *
150 * @exception NoSuchAlgorithmException if no Provider supports a
151 * MessageDigestSpi implementation for the
152 * specified algorithm.
153 *
154 * @see Provider
155 */
156 public static MessageDigest getInstance(String algorithm)
157 throws NoSuchAlgorithmException {
158 try {
159 Object[] objs = Security.getImpl(algorithm, "MessageDigest",
160 (String)null);
161 if (objs[0] instanceof MessageDigest) {
162 MessageDigest md = (MessageDigest)objs[0];
163 md.provider = (Provider)objs[1];
164 return md;
165 } else {
166 MessageDigest delegate =
167 new Delegate((MessageDigestSpi)objs[0], algorithm);
168 delegate.provider = (Provider)objs[1];
169 return delegate;
170 }
171 } catch(NoSuchProviderException e) {
172 throw new NoSuchAlgorithmException(algorithm + " not found");
173 }
174 }
175
176 /**
177 * Returns a MessageDigest object that implements the specified digest
178 * algorithm.
179 *
180 * <p> A new MessageDigest object encapsulating the
181 * MessageDigestSpi implementation from the specified provider
182 * is returned. The specified provider must be registered
183 * in the security provider list.
184 *
185 * <p> Note that the list of registered providers may be retrieved via
186 * the {@link Security#getProviders() Security.getProviders()} method.
187 *
188 * @param algorithm the name of the algorithm requested.
189 * See the MessageDigest section in the <a href=
190 * "{@docRoot}/../technotes/guides/security/StandardNames.html#MessageDigest">
191 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
192 * for information about standard algorithm names.
193 *
194 * @param provider the name of the provider.
195 *
196 * @return a MessageDigest object that implements the specified algorithm.
197 *
198 * @exception NoSuchAlgorithmException if a MessageDigestSpi
199 * implementation for the specified algorithm is not
200 * available from the specified provider.
201 *
202 * @exception NoSuchProviderException if the specified provider is not
203 * registered in the security provider list.
204 *
205 * @exception IllegalArgumentException if the provider name is null
206 * or empty.
207 *
208 * @see Provider
209 */
210 public static MessageDigest getInstance(String algorithm, String provider)
211 throws NoSuchAlgorithmException, NoSuchProviderException
212 {
213 if (provider == null || provider.length() == 0)
214 throw new IllegalArgumentException("missing provider");
215 Object[] objs = Security.getImpl(algorithm, "MessageDigest", provider);
216 if (objs[0] instanceof MessageDigest) {
217 MessageDigest md = (MessageDigest)objs[0];
218 md.provider = (Provider)objs[1];
219 return md;
220 } else {
221 MessageDigest delegate =
222 new Delegate((MessageDigestSpi)objs[0], algorithm);
223 delegate.provider = (Provider)objs[1];
224 return delegate;
225 }
226 }
227
228 /**
229 * Returns a MessageDigest object that implements the specified digest
230 * algorithm.
231 *
232 * <p> A new MessageDigest object encapsulating the
233 * MessageDigestSpi implementation from the specified Provider
234 * object is returned. Note that the specified Provider object
235 * does not have to be registered in the provider list.
236 *
237 * @param algorithm the name of the algorithm requested.
238 * See the MessageDigest section in the <a href=
239 * "{@docRoot}/../technotes/guides/security/StandardNames.html#MessageDigest">
240 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
241 * for information about standard algorithm names.
242 *
243 * @param provider the provider.
244 *
245 * @return a MessageDigest object that implements the specified algorithm.
246 *
247 * @exception NoSuchAlgorithmException if a MessageDigestSpi
248 * implementation for the specified algorithm is not available
249 * from the specified Provider object.
250 *
251 * @exception IllegalArgumentException if the specified provider is null.
252 *
253 * @see Provider
254 *
255 * @since 1.4
256 */
257 public static MessageDigest getInstance(String algorithm,
258 Provider provider)
259 throws NoSuchAlgorithmException
260 {
261 if (provider == null)
262 throw new IllegalArgumentException("missing provider");
263 Object[] objs = Security.getImpl(algorithm, "MessageDigest", provider);
264 if (objs[0] instanceof MessageDigest) {
265 MessageDigest md = (MessageDigest)objs[0];
266 md.provider = (Provider)objs[1];
267 return md;
268 } else {
269 MessageDigest delegate =
270 new Delegate((MessageDigestSpi)objs[0], algorithm);
271 delegate.provider = (Provider)objs[1];
272 return delegate;
273 }
274 }
275
276 /**
277 * Returns the provider of this message digest object.
278 *
279 * @return the provider of this message digest object
280 */
281 public final Provider getProvider() {
282 return this.provider;
283 }
284
285 /**
286 * Updates the digest using the specified byte.
287 *
288 * @param input the byte with which to update the digest.
289 */
290 public void update(byte input) {
291 engineUpdate(input);
292 state = IN_PROGRESS;
293 }
294
295 /**
296 * Updates the digest using the specified array of bytes, starting
297 * at the specified offset.
298 *
299 * @param input the array of bytes.
300 *
301 * @param offset the offset to start from in the array of bytes.
302 *
303 * @param len the number of bytes to use, starting at
304 * <code>offset</code>.
305 */
306 public void update(byte[] input, int offset, int len) {
307 if (input == null) {
308 throw new IllegalArgumentException("No input buffer given");
309 }
310 if (input.length - offset < len) {
311 throw new IllegalArgumentException("Input buffer too short");
312 }
313 engineUpdate(input, offset, len);
314 state = IN_PROGRESS;
315 }
316
317 /**
318 * Updates the digest using the specified array of bytes.
319 *
320 * @param input the array of bytes.
321 */
322 public void update(byte[] input) {
323 engineUpdate(input, 0, input.length);
324 state = IN_PROGRESS;
325 }
326
327 /**
328 * Update the digest using the specified ByteBuffer. The digest is
329 * updated using the <code>input.remaining()</code> bytes starting
330 * at <code>input.position()</code>.
331 * Upon return, the buffer's position will be equal to its limit;
332 * its limit will not have changed.
333 *
334 * @param input the ByteBuffer
335 * @since 1.5
336 */
337 public final void update(ByteBuffer input) {
338 if (input == null) {
339 throw new NullPointerException();
340 }
341 engineUpdate(input);
342 state = IN_PROGRESS;
343 }
344
345 /**
346 * Completes the hash computation by performing final operations
347 * such as padding. The digest is reset after this call is made.
348 *
349 * @return the array of bytes for the resulting hash value.
350 */
351 public byte[] digest() {
352 /* Resetting is the responsibility of implementors. */
353 byte[] result = engineDigest();
354 state = INITIAL;
355 return result;
356 }
357
358 /**
359 * Completes the hash computation by performing final operations
360 * such as padding. The digest is reset after this call is made.
361 *
362 * @param buf output buffer for the computed digest
363 *
364 * @param offset offset into the output buffer to begin storing the digest
365 *
366 * @param len number of bytes within buf allotted for the digest
367 *
368 * @return the number of bytes placed into <code>buf</code>
369 *
370 * @exception DigestException if an error occurs.
371 */
372 public int digest(byte[] buf, int offset, int len) throws DigestException {
373 if (buf == null) {
374 throw new IllegalArgumentException("No output buffer given");
375 }
376 if (buf.length - offset < len) {
377 throw new IllegalArgumentException
378 ("Output buffer too small for specified offset and length");
379 }
380 int numBytes = engineDigest(buf, offset, len);
381 state = INITIAL;
382 return numBytes;
383 }
384
385 /**
386 * Performs a final update on the digest using the specified array
387 * of bytes, then completes the digest computation. That is, this
388 * method first calls {@link #update(byte[]) update(input)},
389 * passing the <i>input</i> array to the <code>update</code> method,
390 * then calls {@link #digest() digest()}.
391 *
392 * @param input the input to be updated before the digest is
393 * completed.
394 *
395 * @return the array of bytes for the resulting hash value.
396 */
397 public byte[] digest(byte[] input) {
398 update(input);
399 return digest();
400 }
401
402 /**
403 * Returns a string representation of this message digest object.
404 */
405 public String toString() {
406 ByteArrayOutputStream baos = new ByteArrayOutputStream();
407 PrintStream p = new PrintStream(baos);
408 p.print(algorithm+" Message Digest from "+provider.getName()+", ");
409 switch (state) {
410 case INITIAL:
411 p.print("<initialized>");
412 break;
413 case IN_PROGRESS:
414 p.print("<in progress>");
415 break;
416 }
417 p.println();
418 return (baos.toString());
419 }
420
421 /**
422 * Compares two digests for equality. Does a simple byte compare.
423 *
424 * @param digesta one of the digests to compare.
425 *
426 * @param digestb the other digest to compare.
427 *
428 * @return true if the digests are equal, false otherwise.
429 */
430 public static boolean isEqual(byte[] digesta, byte[] digestb) {
431 if (digesta.length != digestb.length) {
432 return false;
433 }
434
435 int result = 0;
436 // time-constant comparison
437 for (int i = 0; i < digesta.length; i++) {
438 result |= digesta[i] ^ digestb[i];
439 }
440 return result == 0;
441 }
442
443 /**
444 * Resets the digest for further use.
445 */
446 public void reset() {
447 engineReset();
448 state = INITIAL;
449 }
450
451 /**
452 * Returns a string that identifies the algorithm, independent of
453 * implementation details. The name should be a standard
454 * Java Security name (such as "SHA", "MD5", and so on).
455 * See the MessageDigest section in the <a href=
456 * "{@docRoot}/../technotes/guides/security/StandardNames.html#MessageDigest">
457 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
458 * for information about standard algorithm names.
459 *
460 * @return the name of the algorithm
461 */
462 public final String getAlgorithm() {
463 return this.algorithm;
464 }
465
466 /**
467 * Returns the length of the digest in bytes, or 0 if this operation is
468 * not supported by the provider and the implementation is not cloneable.
469 *
470 * @return the digest length in bytes, or 0 if this operation is not
471 * supported by the provider and the implementation is not cloneable.
472 *
473 * @since 1.2
474 */
475 public final int getDigestLength() {
476 int digestLen = engineGetDigestLength();
477 if (digestLen == 0) {
478 try {
479 MessageDigest md = (MessageDigest)clone();
480 byte[] digest = md.digest();
481 return digest.length;
482 } catch (CloneNotSupportedException e) {
483 return digestLen;
484 }
485 }
486 return digestLen;
487 }
488
489 /**
490 * Returns a clone if the implementation is cloneable.
491 *
492 * @return a clone if the implementation is cloneable.
493 *
494 * @exception CloneNotSupportedException if this is called on an
495 * implementation that does not support <code>Cloneable</code>.
496 */
497 public Object clone() throws CloneNotSupportedException {
498 if (this instanceof Cloneable) {
499 return super.clone();
500 } else {
501 throw new CloneNotSupportedException();
502 }
503 }
504
505
506
507
508 /*
509 * The following class allows providers to extend from MessageDigestSpi
510 * rather than from MessageDigest. It represents a MessageDigest with an
511 * encapsulated, provider-supplied SPI object (of type MessageDigestSpi).
512 * If the provider implementation is an instance of MessageDigestSpi,
513 * the getInstance() methods above return an instance of this class, with
514 * the SPI object encapsulated.
515 *
516 * Note: All SPI methods from the original MessageDigest class have been
517 * moved up the hierarchy into a new class (MessageDigestSpi), which has
518 * been interposed in the hierarchy between the API (MessageDigest)
519 * and its original parent (Object).
520 */
521
522 static class Delegate extends MessageDigest {
523
524 // The provider implementation (delegate)
525 private MessageDigestSpi digestSpi;
526
527 // constructor
528 public Delegate(MessageDigestSpi digestSpi, String algorithm) {
529 super(algorithm);
530 this.digestSpi = digestSpi;
531 }
532
533 /**
534 * Returns a clone if the delegate is cloneable.
535 *
536 * @return a clone if the delegate is cloneable.
537 *
538 * @exception CloneNotSupportedException if this is called on a
539 * delegate that does not support <code>Cloneable</code>.
540 */
541 public Object clone() throws CloneNotSupportedException {
542 if (digestSpi instanceof Cloneable) {
543 MessageDigestSpi digestSpiClone =
544 (MessageDigestSpi)digestSpi.clone();
545 // Because 'algorithm', 'provider', and 'state' are private
546 // members of our supertype, we must perform a cast to
547 // access them.
548 MessageDigest that =
549 new Delegate(digestSpiClone,
550 ((MessageDigest)this).algorithm);
551 that.provider = ((MessageDigest)this).provider;
552 that.state = ((MessageDigest)this).state;
553 return that;
554 } else {
555 throw new CloneNotSupportedException();
556 }
557 }
558
559 protected int engineGetDigestLength() {
560 return digestSpi.engineGetDigestLength();
561 }
562
563 protected void engineUpdate(byte input) {
564 digestSpi.engineUpdate(input);
565 }
566
567 protected void engineUpdate(byte[] input, int offset, int len) {
568 digestSpi.engineUpdate(input, offset, len);
569 }
570
571 protected void engineUpdate(ByteBuffer input) {
572 digestSpi.engineUpdate(input);
573 }
574
575 protected byte[] engineDigest() {
576 return digestSpi.engineDigest();
577 }
578
579 protected int engineDigest(byte[] buf, int offset, int len)
580 throws DigestException {
581 return digestSpi.engineDigest(buf, offset, len);
582 }
583
584 protected void engineReset() {
585 digestSpi.engineReset();
586 }
587 }
588 }