1 /*
2 * Copyright (c) 1997, 2014, 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.util.*;
29
30 import java.security.*;
31 import java.security.Provider.Service;
32 import java.security.spec.*;
33
34 import sun.security.jca.*;
35 import sun.security.jca.GetInstance.Instance;
36 import sun.security.util.Debug;
37
38 /**
39 * This class provides the functionality of a secret (symmetric) key generator.
40 *
41 * <p>Key generators are constructed using one of the {@code getInstance}
42 * class methods of this class.
43 *
44 * <p>KeyGenerator objects are reusable, i.e., after a key has been
45 * generated, the same KeyGenerator object can be re-used to generate further
46 * keys.
47 *
48 * <p>There are two ways to generate a key: in an algorithm-independent
49 * manner, and in an algorithm-specific manner.
50 * The only difference between the two is the initialization of the object:
51 *
52 * <ul>
53 * <li><b>Algorithm-Independent Initialization</b>
54 * <p>All key generators share the concepts of a <i>keysize</i> and a
55 * <i>source of randomness</i>.
56 * There is an
57 * {@link #init(int, java.security.SecureRandom) init}
58 * method in this KeyGenerator class that takes these two universally
59 * shared types of arguments. There is also one that takes just a
60 * {@code keysize} argument, and uses the SecureRandom implementation
61 * of the highest-priority installed provider as the source of randomness
62 * (or a system-provided source of randomness if none of the installed
63 * providers supply a SecureRandom implementation), and one that takes just a
64 * source of randomness.
65 *
66 * <p>Since no other parameters are specified when you call the above
67 * algorithm-independent {@code init} methods, it is up to the
68 * provider what to do about the algorithm-specific parameters (if any) to be
69 * associated with each of the keys.
70 *
71 * <li><b>Algorithm-Specific Initialization</b>
72 * <p>For situations where a set of algorithm-specific parameters already
73 * exists, there are two
74 * {@link #init(java.security.spec.AlgorithmParameterSpec) init}
75 * methods that have an {@code AlgorithmParameterSpec}
76 * argument. One also has a {@code SecureRandom} argument, while the
77 * other uses the SecureRandom implementation
78 * of the highest-priority installed provider as the source of randomness
79 * (or a system-provided source of randomness if none of the installed
80 * providers supply a SecureRandom implementation).
81 * </ul>
82 *
83 * <p>In case the client does not explicitly initialize the KeyGenerator
84 * (via a call to an {@code init} method), each provider must
85 * supply (and document) a default initialization.
86 *
87 * <p> Every implementation of the Java platform is required to support the
88 * following standard {@code KeyGenerator} algorithms with the keysizes in
89 * parentheses:
90 * <ul>
91 * <li>{@code AES} (128)</li>
92 * <li>{@code DES} (56)</li>
93 * <li>{@code DESede} (168)</li>
94 * <li>{@code HmacSHA1}</li>
95 * <li>{@code HmacSHA256}</li>
96 * </ul>
97 * These algorithms are described in the <a href=
98 * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyGenerator">
99 * KeyGenerator section</a> of the
100 * Java Cryptography Architecture Standard Algorithm Name Documentation.
101 * Consult the release documentation for your implementation to see if any
102 * other algorithms are supported.
103 *
104 * @author Jan Luehe
105 *
106 * @see SecretKey
107 * @since 1.4
108 */
109
110 public class KeyGenerator {
111
112 private static final Debug pdebug =
113 Debug.getInstance("provider", "Provider");
114 private static final boolean skipDebug =
115 Debug.isOn("engine=") && !Debug.isOn("keygenerator");
116
117 // see java.security.KeyPairGenerator for failover notes
118
119 private final static int I_NONE = 1;
120 private final static int I_RANDOM = 2;
121 private final static int I_PARAMS = 3;
122 private final static int I_SIZE = 4;
123
124 // The provider
125 private Provider provider;
126
127 // The provider implementation (delegate)
128 private volatile KeyGeneratorSpi spi;
129
130 // The algorithm
131 private final String algorithm;
132
133 private final Object lock = new Object();
134
135 private Iterator<Service> serviceIterator;
136
137 private int initType;
138 private int initKeySize;
139 private AlgorithmParameterSpec initParams;
140 private SecureRandom initRandom;
141
142 /**
143 * Creates a KeyGenerator object.
144 *
145 * @param keyGenSpi the delegate
146 * @param provider the provider
147 * @param algorithm the algorithm
148 */
149 protected KeyGenerator(KeyGeneratorSpi keyGenSpi, Provider provider,
150 String algorithm) {
151 this.spi = keyGenSpi;
152 this.provider = provider;
153 this.algorithm = algorithm;
154
155 if (!skipDebug && pdebug != null) {
156 pdebug.println("KeyGenerator." + algorithm + " algorithm from: " +
157 this.provider.getName());
158 }
159 }
160
161 private KeyGenerator(String algorithm) throws NoSuchAlgorithmException {
162 this.algorithm = algorithm;
163 List<Service> list =
164 GetInstance.getServices("KeyGenerator", algorithm);
165 serviceIterator = list.iterator();
166 initType = I_NONE;
167 // fetch and instantiate initial spi
168 if (nextSpi(null, false) == null) {
169 throw new NoSuchAlgorithmException
170 (algorithm + " KeyGenerator not available");
171 }
172
173 if (!skipDebug && pdebug != null) {
174 pdebug.println("KeyGenerator." + algorithm + " algorithm from: " +
175 this.provider.getName());
176 }
177 }
178
179 /**
180 * Returns the algorithm name of this {@code KeyGenerator} object.
181 *
182 * <p>This is the same name that was specified in one of the
183 * {@code getInstance} calls that created this
184 * {@code KeyGenerator} object.
185 *
186 * @return the algorithm name of this {@code KeyGenerator} object.
187 */
188 public final String getAlgorithm() {
189 return this.algorithm;
190 }
191
192 /**
193 * Returns a {@code KeyGenerator} object that generates secret keys
194 * for the specified algorithm.
195 *
196 * <p> This method traverses the list of registered security Providers,
197 * starting with the most preferred Provider.
198 * A new KeyGenerator object encapsulating the
199 * KeyGeneratorSpi implementation from the first
200 * Provider that supports the specified algorithm is returned.
201 *
202 * <p> Note that the list of registered providers may be retrieved via
203 * the {@link Security#getProviders() Security.getProviders()} method.
204 *
205 * @param algorithm the standard name of the requested key algorithm.
206 * See the KeyGenerator section in the <a href=
207 * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyGenerator">
208 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
209 * for information about standard algorithm names.
210 *
211 * @return the new {@code KeyGenerator} object.
212 *
213 * @exception NullPointerException if the specified algorithm is null.
214 *
215 * @exception NoSuchAlgorithmException if no Provider supports a
216 * KeyGeneratorSpi implementation for the
217 * specified algorithm.
218 *
219 * @see java.security.Provider
220 */
221 public static final KeyGenerator getInstance(String algorithm)
222 throws NoSuchAlgorithmException {
223 return new KeyGenerator(algorithm);
224 }
225
226 /**
227 * Returns a {@code KeyGenerator} object that generates secret keys
228 * for the specified algorithm.
229 *
230 * <p> A new KeyGenerator object encapsulating the
231 * KeyGeneratorSpi implementation from the specified provider
232 * is returned. The specified provider must be registered
233 * in the security provider list.
234 *
235 * <p> Note that the list of registered providers may be retrieved via
236 * the {@link Security#getProviders() Security.getProviders()} method.
237 *
238 * @param algorithm the standard name of the requested key algorithm.
239 * See the KeyGenerator section in the <a href=
240 * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyGenerator">
241 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
242 * for information about standard algorithm names.
243 *
244 * @param provider the name of the provider.
245 *
246 * @return the new {@code KeyGenerator} object.
247 *
248 * @exception NullPointerException if the specified algorithm is null.
249 *
250 * @exception NoSuchAlgorithmException if a KeyGeneratorSpi
251 * implementation for the specified algorithm is not
252 * available from the specified provider.
253 *
254 * @exception NoSuchProviderException if the specified provider is not
255 * registered in the security provider list.
256 *
257 * @exception IllegalArgumentException if the {@code provider}
258 * is null or empty.
259 *
260 * @see java.security.Provider
261 */
262 public static final KeyGenerator getInstance(String algorithm,
263 String provider) throws NoSuchAlgorithmException,
264 NoSuchProviderException {
265 Instance instance = JceSecurity.getInstance("KeyGenerator",
266 KeyGeneratorSpi.class, algorithm, provider);
267 return new KeyGenerator((KeyGeneratorSpi)instance.impl,
268 instance.provider, algorithm);
269 }
270
271 /**
272 * Returns a {@code KeyGenerator} object that generates secret keys
273 * for the specified algorithm.
274 *
275 * <p> A new KeyGenerator object encapsulating the
276 * KeyGeneratorSpi implementation from the specified Provider
277 * object is returned. Note that the specified Provider object
278 * does not have to be registered in the provider list.
279 *
280 * @param algorithm the standard name of the requested key algorithm.
281 * See the KeyGenerator section in the <a href=
282 * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyGenerator">
283 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
284 * for information about standard algorithm names.
285 *
286 * @param provider the provider.
287 *
288 * @return the new {@code KeyGenerator} object.
289 *
290 * @exception NullPointerException if the specified algorithm is null.
291 *
292 * @exception NoSuchAlgorithmException if a KeyGeneratorSpi
293 * implementation for the specified algorithm is not available
294 * from the specified Provider object.
295 *
296 * @exception IllegalArgumentException if the {@code provider}
297 * is null.
298 *
299 * @see java.security.Provider
300 */
301 public static final KeyGenerator getInstance(String algorithm,
302 Provider provider) throws NoSuchAlgorithmException {
303 Instance instance = JceSecurity.getInstance("KeyGenerator",
304 KeyGeneratorSpi.class, algorithm, provider);
305 return new KeyGenerator((KeyGeneratorSpi)instance.impl,
306 instance.provider, algorithm);
307 }
308
309 /**
310 * Returns the provider of this {@code KeyGenerator} object.
311 *
312 * @return the provider of this {@code KeyGenerator} object
313 */
314 public final Provider getProvider() {
315 synchronized (lock) {
316 disableFailover();
317 return provider;
318 }
319 }
320
321 /**
322 * Update the active spi of this class and return the next
323 * implementation for failover. If no more implementations are
324 * available, this method returns null. However, the active spi of
325 * this class is never set to null.
326 */
327 private KeyGeneratorSpi nextSpi(KeyGeneratorSpi oldSpi,
328 boolean reinit) {
329 synchronized (lock) {
330 // somebody else did a failover concurrently
331 // try that spi now
332 if ((oldSpi != null) && (oldSpi != spi)) {
333 return spi;
334 }
335 if (serviceIterator == null) {
336 return null;
337 }
338 while (serviceIterator.hasNext()) {
339 Service s = serviceIterator.next();
340 if (JceSecurity.canUseProvider(s.getProvider()) == false) {
341 continue;
342 }
343 try {
344 Object inst = s.newInstance(null);
345 // ignore non-spis
346 if (inst instanceof KeyGeneratorSpi == false) {
347 continue;
348 }
349 KeyGeneratorSpi spi = (KeyGeneratorSpi)inst;
350 if (reinit) {
351 if (initType == I_SIZE) {
352 spi.engineInit(initKeySize, initRandom);
353 } else if (initType == I_PARAMS) {
354 spi.engineInit(initParams, initRandom);
355 } else if (initType == I_RANDOM) {
356 spi.engineInit(initRandom);
357 } else if (initType != I_NONE) {
358 throw new AssertionError
359 ("KeyGenerator initType: " + initType);
360 }
361 }
362 provider = s.getProvider();
363 this.spi = spi;
364 return spi;
365 } catch (Exception e) {
366 // ignore
367 }
368 }
369 disableFailover();
370 return null;
371 }
372 }
373
374 void disableFailover() {
375 serviceIterator = null;
376 initType = 0;
377 initParams = null;
378 initRandom = null;
379 }
380
381 /**
382 * Initializes this key generator.
383 *
384 * @param random the source of randomness for this generator
385 */
386 public final void init(SecureRandom random) {
387 if (serviceIterator == null) {
388 spi.engineInit(random);
389 return;
390 }
391 RuntimeException failure = null;
392 KeyGeneratorSpi mySpi = spi;
393 do {
394 try {
395 mySpi.engineInit(random);
396 initType = I_RANDOM;
397 initKeySize = 0;
398 initParams = null;
399 initRandom = random;
400 return;
401 } catch (RuntimeException e) {
402 if (failure == null) {
403 failure = e;
404 }
405 mySpi = nextSpi(mySpi, false);
406 }
407 } while (mySpi != null);
408 throw failure;
409 }
410
411 /**
412 * Initializes this key generator with the specified parameter set.
413 *
414 * <p> If this key generator requires any random bytes, it will get them
415 * using the
416 * {@link java.security.SecureRandom}
417 * implementation of the highest-priority installed
418 * provider as the source of randomness.
419 * (If none of the installed providers supply an implementation of
420 * SecureRandom, a system-provided source of randomness will be used.)
421 *
422 * @param params the key generation parameters
423 *
424 * @exception InvalidAlgorithmParameterException if the given parameters
425 * are inappropriate for this key generator
426 */
427 public final void init(AlgorithmParameterSpec params)
428 throws InvalidAlgorithmParameterException
429 {
430 init(params, JceSecurity.RANDOM);
431 }
432
433 /**
434 * Initializes this key generator with the specified parameter
435 * set and a user-provided source of randomness.
436 *
437 * @param params the key generation parameters
438 * @param random the source of randomness for this key generator
439 *
440 * @exception InvalidAlgorithmParameterException if {@code params} is
441 * inappropriate for this key generator
442 */
443 public final void init(AlgorithmParameterSpec params, SecureRandom random)
444 throws InvalidAlgorithmParameterException
445 {
446 if (serviceIterator == null) {
447 spi.engineInit(params, random);
448 return;
449 }
450 Exception failure = null;
451 KeyGeneratorSpi mySpi = spi;
452 do {
453 try {
454 mySpi.engineInit(params, random);
455 initType = I_PARAMS;
456 initKeySize = 0;
457 initParams = params;
458 initRandom = random;
459 return;
460 } catch (Exception e) {
461 if (failure == null) {
462 failure = e;
463 }
464 mySpi = nextSpi(mySpi, false);
465 }
466 } while (mySpi != null);
467 if (failure instanceof InvalidAlgorithmParameterException) {
468 throw (InvalidAlgorithmParameterException)failure;
469 }
470 if (failure instanceof RuntimeException) {
471 throw (RuntimeException)failure;
472 }
473 throw new InvalidAlgorithmParameterException("init() failed", failure);
474 }
475
476 /**
477 * Initializes this key generator for a certain keysize.
478 *
479 * <p> If this key generator requires any random bytes, it will get them
480 * using the
481 * {@link java.security.SecureRandom}
482 * implementation of the highest-priority installed
483 * provider as the source of randomness.
484 * (If none of the installed providers supply an implementation of
485 * SecureRandom, a system-provided source of randomness will be used.)
486 *
487 * @param keysize the keysize. This is an algorithm-specific metric,
488 * specified in number of bits.
489 *
490 * @exception InvalidParameterException if the keysize is wrong or not
491 * supported.
492 */
493 public final void init(int keysize) {
494 init(keysize, JceSecurity.RANDOM);
495 }
496
497 /**
498 * Initializes this key generator for a certain keysize, using a
499 * user-provided source of randomness.
500 *
501 * @param keysize the keysize. This is an algorithm-specific metric,
502 * specified in number of bits.
503 * @param random the source of randomness for this key generator
504 *
505 * @exception InvalidParameterException if the keysize is wrong or not
506 * supported.
507 */
508 public final void init(int keysize, SecureRandom random) {
509 if (serviceIterator == null) {
510 spi.engineInit(keysize, random);
511 return;
512 }
513 RuntimeException failure = null;
514 KeyGeneratorSpi mySpi = spi;
515 do {
516 try {
517 mySpi.engineInit(keysize, random);
518 initType = I_SIZE;
519 initKeySize = keysize;
520 initParams = null;
521 initRandom = random;
522 return;
523 } catch (RuntimeException e) {
524 if (failure == null) {
525 failure = e;
526 }
527 mySpi = nextSpi(mySpi, false);
528 }
529 } while (mySpi != null);
530 throw failure;
531 }
532
533 /**
534 * Generates a secret key.
535 *
536 * @return the new key
537 */
538 public final SecretKey generateKey() {
539 if (serviceIterator == null) {
540 return spi.engineGenerateKey();
541 }
542 RuntimeException failure = null;
543 KeyGeneratorSpi mySpi = spi;
544 do {
545 try {
546 return mySpi.engineGenerateKey();
547 } catch (RuntimeException e) {
548 if (failure == null) {
549 failure = e;
550 }
551 mySpi = nextSpi(mySpi, true);
552 }
553 } while (mySpi != null);
554 throw failure;
555 }
556 }