1 /*
2 * Copyright (c) 1999, 2010, 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.security.AlgorithmParameters;
29 import java.security.Provider;
30 import java.security.Key;
31 import java.security.Security;
32 import java.security.NoSuchAlgorithmException;
33 import java.security.NoSuchProviderException;
34 import java.security.InvalidKeyException;
35 import java.security.InvalidAlgorithmParameterException;
36 import java.security.spec.AlgorithmParameterSpec;
37
38 import sun.security.jca.GetInstance.Instance;
39
40 /**
41 * This class provides the functionality of an exemption mechanism, examples
42 * of which are <i>key recovery</i>, <i>key weakening</i>, and
43 * <i>key escrow</i>.
44 *
45 * <p>Applications or applets that use an exemption mechanism may be granted
46 * stronger encryption capabilities than those which don't.
47 *
48 * @since 1.4
49 */
50
51 public class ExemptionMechanism {
52
53 // The provider
54 private Provider provider;
55
56 // The provider implementation (delegate)
57 private ExemptionMechanismSpi exmechSpi;
58
59 // The name of the exemption mechanism.
60 private String mechanism;
61
62 // Flag which indicates whether this ExemptionMechanism
63 // result is generated successfully.
64 private boolean done = false;
65
66 // State information
67 private boolean initialized = false;
68
69 // Store away the key at init() time for later comparison.
70 private Key keyStored = null;
71
72 /**
73 * Creates a ExemptionMechanism object.
74 *
75 * @param exmechSpi the delegate
76 * @param provider the provider
77 * @param mechanism the exemption mechanism
78 */
79 protected ExemptionMechanism(ExemptionMechanismSpi exmechSpi,
80 Provider provider,
81 String mechanism) {
82 this.exmechSpi = exmechSpi;
83 this.provider = provider;
84 this.mechanism = mechanism;
85 }
86
87 /**
88 * Returns the exemption mechanism name of this
89 * <code>ExemptionMechanism</code> object.
90 *
91 * <p>This is the same name that was specified in one of the
92 * <code>getInstance</code> calls that created this
93 * <code>ExemptionMechanism</code> object.
94 *
95 * @return the exemption mechanism name of this
96 * <code>ExemptionMechanism</code> object.
97 */
98 public final String getName() {
99 return this.mechanism;
100 }
101
102 /**
103 * Returns an <code>ExemptionMechanism</code> object that implements the
104 * specified exemption mechanism algorithm.
105 *
106 * <p> This method traverses the list of registered security Providers,
107 * starting with the most preferred Provider.
108 * A new ExemptionMechanism object encapsulating the
109 * ExemptionMechanismSpi implementation from the first
110 * Provider that supports the specified algorithm is returned.
111 *
112 * <p> Note that the list of registered providers may be retrieved via
113 * the {@link Security#getProviders() Security.getProviders()} method.
114 *
115 * @param algorithm the standard name of the requested exemption
116 * mechanism.
117 * See the ExemptionMechanism section in the
118 * <a href=
119 * "{docRoot}/../technotes/guides/security/StandardNames.html#Exemption">
120 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
121 * for information about standard exemption mechanism names.
122 *
123 * @return the new <code>ExemptionMechanism</code> object.
124 *
125 * @exception NullPointerException if <code>algorithm</code>
126 * is null.
127 *
128 * @exception NoSuchAlgorithmException if no Provider supports an
129 * ExemptionMechanismSpi implementation for the
130 * specified algorithm.
131 *
132 * @see java.security.Provider
133 */
134 public static final ExemptionMechanism getInstance(String algorithm)
135 throws NoSuchAlgorithmException {
136 Instance instance = JceSecurity.getInstance("ExemptionMechanism",
137 ExemptionMechanismSpi.class, algorithm);
138 return new ExemptionMechanism((ExemptionMechanismSpi)instance.impl,
139 instance.provider, algorithm);
140 }
141
142
143 /**
144 * Returns an <code>ExemptionMechanism</code> object that implements the
145 * specified exemption mechanism algorithm.
146 *
147 * <p> A new ExemptionMechanism object encapsulating the
148 * ExemptionMechanismSpi implementation from the specified provider
149 * is returned. The specified provider must be registered
150 * in the security provider list.
151 *
152 * <p> Note that the list of registered providers may be retrieved via
153 * the {@link Security#getProviders() Security.getProviders()} method.
154
155 * @param algorithm the standard name of the requested exemption mechanism.
156 * See the ExemptionMechanism section in the
157 * <a href=
158 * "{docRoot}/../technotes/guides/security/StandardNames.html#Exemption">
159 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
160 * for information about standard exemption mechanism names.
161 *
162 * @param provider the name of the provider.
163 *
164 * @return the new <code>ExemptionMechanism</code> object.
165 *
166 * @exception NullPointerException if <code>algorithm</code>
167 * is null.
168 *
169 * @exception NoSuchAlgorithmException if an ExemptionMechanismSpi
170 * implementation for the specified algorithm is not
171 * available from the specified provider.
172 *
173 * @exception NoSuchProviderException if the specified provider is not
174 * registered in the security provider list.
175 *
176 * @exception IllegalArgumentException if the <code>provider</code>
177 * is null or empty.
178 *
179 * @see java.security.Provider
180 */
181 public static final ExemptionMechanism getInstance(String algorithm,
182 String provider) throws NoSuchAlgorithmException,
183 NoSuchProviderException {
184 Instance instance = JceSecurity.getInstance("ExemptionMechanism",
185 ExemptionMechanismSpi.class, algorithm, provider);
186 return new ExemptionMechanism((ExemptionMechanismSpi)instance.impl,
187 instance.provider, algorithm);
188 }
189
190 /**
191 * Returns an <code>ExemptionMechanism</code> object that implements the
192 * specified exemption mechanism algorithm.
193 *
194 * <p> A new ExemptionMechanism object encapsulating the
195 * ExemptionMechanismSpi implementation from the specified Provider
196 * object is returned. Note that the specified Provider object
197 * does not have to be registered in the provider list.
198 *
199 * @param algorithm the standard name of the requested exemption mechanism.
200 * See the ExemptionMechanism section in the
201 * <a href=
202 * "{docRoot}/../technotes/guides/security/StandardNames.html#Exemption">
203 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
204 * for information about standard exemption mechanism names.
205 *
206 * @param provider the provider.
207 *
208 * @return the new <code>ExemptionMechanism</code> object.
209 *
210 * @exception NullPointerException if <code>algorithm</code>
211 * is null.
212 *
213 * @exception NoSuchAlgorithmException if an ExemptionMechanismSpi
214 * implementation for the specified algorithm is not available
215 * from the specified Provider object.
216 *
217 * @exception IllegalArgumentException if the <code>provider</code>
218 * is null.
219 *
220 * @see java.security.Provider
221 */
222 public static final ExemptionMechanism getInstance(String algorithm,
223 Provider provider) throws NoSuchAlgorithmException {
224 Instance instance = JceSecurity.getInstance("ExemptionMechanism",
225 ExemptionMechanismSpi.class, algorithm, provider);
226 return new ExemptionMechanism((ExemptionMechanismSpi)instance.impl,
227 instance.provider, algorithm);
228 }
229
230 /**
231 * Returns the provider of this <code>ExemptionMechanism</code> object.
232 *
233 * @return the provider of this <code>ExemptionMechanism</code> object.
234 */
235 public final Provider getProvider() {
236 return this.provider;
237 }
238
239 /**
240 * Returns whether the result blob has been generated successfully by this
241 * exemption mechanism.
242 *
243 * <p>The method also makes sure that the key passed in is the same as
244 * the one this exemption mechanism used in initializing and generating
245 * phases.
246 *
247 * @param key the key the crypto is going to use.
248 *
249 * @return whether the result blob of the same key has been generated
250 * successfully by this exemption mechanism; false if <code>key</code>
251 * is null.
252 *
253 * @exception ExemptionMechanismException if problem(s) encountered
254 * while determining whether the result blob has been generated successfully
255 * by this exemption mechanism object.
256 */
257 public final boolean isCryptoAllowed(Key key)
258 throws ExemptionMechanismException {
259 boolean ret = false;
260 if (done && (key != null)) {
261 // Check if the key passed in is the same as the one
262 // this exemption mechanism used.
263 ret = keyStored.equals(key);
264 }
265 return ret;
266 }
267
268 /**
269 * Returns the length in bytes that an output buffer would need to be in
270 * order to hold the result of the next
271 * {@link #genExemptionBlob(byte[]) genExemptionBlob}
272 * operation, given the input length <code>inputLen</code> (in bytes).
273 *
274 * <p>The actual output length of the next
275 * {@link #genExemptionBlob(byte[]) genExemptionBlob}
276 * call may be smaller than the length returned by this method.
277 *
278 * @param inputLen the input length (in bytes)
279 *
280 * @return the required output buffer size (in bytes)
281 *
282 * @exception IllegalStateException if this exemption mechanism is in a
283 * wrong state (e.g., has not yet been initialized)
284 */
285 public final int getOutputSize(int inputLen) throws IllegalStateException {
286 if (!initialized) {
287 throw new IllegalStateException(
288 "ExemptionMechanism not initialized");
289 }
290 if (inputLen < 0) {
291 throw new IllegalArgumentException(
292 "Input size must be equal to " + "or greater than zero");
293 }
294 return exmechSpi.engineGetOutputSize(inputLen);
295 }
296
297 /**
298 * Initializes this exemption mechanism with a key.
299 *
300 * <p>If this exemption mechanism requires any algorithm parameters
301 * that cannot be derived from the given <code>key</code>, the
302 * underlying exemption mechanism implementation is supposed to
303 * generate the required parameters itself (using provider-specific
304 * default values); in the case that algorithm parameters must be
305 * specified by the caller, an <code>InvalidKeyException</code> is raised.
306 *
307 * @param key the key for this exemption mechanism
308 *
309 * @exception InvalidKeyException if the given key is inappropriate for
310 * this exemption mechanism.
311 * @exception ExemptionMechanismException if problem(s) encountered in the
312 * process of initializing.
313 */
314 public final void init(Key key)
315 throws InvalidKeyException, ExemptionMechanismException {
316 done = false;
317 initialized = false;
318
319 keyStored = key;
320 exmechSpi.engineInit(key);
321 initialized = true;
322 }
323
324 /**
325 * Initializes this exemption mechanism with a key and a set of algorithm
326 * parameters.
327 *
328 * <p>If this exemption mechanism requires any algorithm parameters
329 * and <code>params</code> is null, the underlying exemption
330 * mechanism implementation is supposed to generate the required
331 * parameters itself (using provider-specific default values); in the case
332 * that algorithm parameters must be specified by the caller, an
333 * <code>InvalidAlgorithmParameterException</code> is raised.
334 *
335 * @param key the key for this exemption mechanism
336 * @param params the algorithm parameters
337 *
338 * @exception InvalidKeyException if the given key is inappropriate for
339 * this exemption mechanism.
340 * @exception InvalidAlgorithmParameterException if the given algorithm
341 * parameters are inappropriate for this exemption mechanism.
342 * @exception ExemptionMechanismException if problem(s) encountered in the
343 * process of initializing.
344 */
345 public final void init(Key key, AlgorithmParameterSpec params)
346 throws InvalidKeyException, InvalidAlgorithmParameterException,
347 ExemptionMechanismException {
348 done = false;
349 initialized = false;
350
351 keyStored = key;
352 exmechSpi.engineInit(key, params);
353 initialized = true;
354 }
355
356 /**
357 * Initializes this exemption mechanism with a key and a set of algorithm
358 * parameters.
359 *
360 * <p>If this exemption mechanism requires any algorithm parameters
361 * and <code>params</code> is null, the underlying exemption mechanism
362 * implementation is supposed to generate the required parameters itself
363 * (using provider-specific default values); in the case that algorithm
364 * parameters must be specified by the caller, an
365 * <code>InvalidAlgorithmParameterException</code> is raised.
366 *
367 * @param key the key for this exemption mechanism
368 * @param params the algorithm parameters
369 *
370 * @exception InvalidKeyException if the given key is inappropriate for
371 * this exemption mechanism.
372 * @exception InvalidAlgorithmParameterException if the given algorithm
373 * parameters are inappropriate for this exemption mechanism.
374 * @exception ExemptionMechanismException if problem(s) encountered in the
375 * process of initializing.
376 */
377 public final void init(Key key, AlgorithmParameters params)
378 throws InvalidKeyException, InvalidAlgorithmParameterException,
379 ExemptionMechanismException {
380 done = false;
381 initialized = false;
382
383 keyStored = key;
384 exmechSpi.engineInit(key, params);
385 initialized = true;
386 }
387
388 /**
389 * Generates the exemption mechanism key blob.
390 *
391 * @return the new buffer with the result key blob.
392 *
393 * @exception IllegalStateException if this exemption mechanism is in
394 * a wrong state (e.g., has not been initialized).
395 * @exception ExemptionMechanismException if problem(s) encountered in the
396 * process of generating.
397 */
398 public final byte[] genExemptionBlob() throws IllegalStateException,
399 ExemptionMechanismException {
400 if (!initialized) {
401 throw new IllegalStateException(
402 "ExemptionMechanism not initialized");
403 }
404 byte[] blob = exmechSpi.engineGenExemptionBlob();
405 done = true;
406 return blob;
407 }
408
409 /**
410 * Generates the exemption mechanism key blob, and stores the result in
411 * the <code>output</code> buffer.
412 *
413 * <p>If the <code>output</code> buffer is too small to hold the result,
414 * a <code>ShortBufferException</code> is thrown. In this case, repeat this
415 * call with a larger output buffer. Use
416 * {@link #getOutputSize(int) getOutputSize} to determine how big
417 * the output buffer should be.
418 *
419 * @param output the buffer for the result
420 *
421 * @return the number of bytes stored in <code>output</code>
422 *
423 * @exception IllegalStateException if this exemption mechanism is in
424 * a wrong state (e.g., has not been initialized).
425 * @exception ShortBufferException if the given output buffer is too small
426 * to hold the result.
427 * @exception ExemptionMechanismException if problem(s) encountered in the
428 * process of generating.
429 */
430 public final int genExemptionBlob(byte[] output)
431 throws IllegalStateException, ShortBufferException,
432 ExemptionMechanismException {
433 if (!initialized) {
434 throw new IllegalStateException
435 ("ExemptionMechanism not initialized");
436 }
437 int n = exmechSpi.engineGenExemptionBlob(output, 0);
438 done = true;
439 return n;
440 }
441
442 /**
443 * Generates the exemption mechanism key blob, and stores the result in
444 * the <code>output</code> buffer, starting at <code>outputOffset</code>
445 * inclusive.
446 *
447 * <p>If the <code>output</code> buffer is too small to hold the result,
448 * a <code>ShortBufferException</code> is thrown. In this case, repeat this
449 * call with a larger output buffer. Use
450 * {@link #getOutputSize(int) getOutputSize} to determine how big
451 * the output buffer should be.
452 *
453 * @param output the buffer for the result
454 * @param outputOffset the offset in <code>output</code> where the result
455 * is stored
456 *
457 * @return the number of bytes stored in <code>output</code>
458 *
459 * @exception IllegalStateException if this exemption mechanism is in
460 * a wrong state (e.g., has not been initialized).
461 * @exception ShortBufferException if the given output buffer is too small
462 * to hold the result.
463 * @exception ExemptionMechanismException if problem(s) encountered in the
464 * process of generating.
465 */
466 public final int genExemptionBlob(byte[] output, int outputOffset)
467 throws IllegalStateException, ShortBufferException,
468 ExemptionMechanismException {
469 if (!initialized) {
470 throw new IllegalStateException
471 ("ExemptionMechanism not initialized");
472 }
473 int n = exmechSpi.engineGenExemptionBlob(output, outputOffset);
474 done = true;
475 return n;
476 }
477
478 /**
479 * Ensures that the key stored away by this ExemptionMechanism
480 * object will be wiped out when there are no more references to it.
481 */
482 protected void finalize() {
483 keyStored = null;
484 // Are there anything else we could do?
485 }
486 }