1 /*
2 * Copyright (c) 1997, 2015, 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 static final int I_NONE = 1;
120 private static final int I_RANDOM = 2;
121 private static final int I_PARAMS = 3;
122 private static final 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 * @implNote
206 * The JDK Reference Implementation additionally uses the
207 * {@code jdk.security.provider.preferred} property to determine
208 * the preferred provider order for the specified algorithm. This
209 * may be different than the order of providers returned by
210 * {@link Security#getProviders() Security.getProviders()}.
211 *
212 * @param algorithm the standard name of the requested key algorithm.
213 * See the KeyGenerator section in the <a href=
214 * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyGenerator">
215 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
216 * for information about standard algorithm names.
217 *
218 * @return the new {@code KeyGenerator} object.
219 *
220 * @exception NullPointerException if the specified algorithm is null.
221 *
222 * @exception NoSuchAlgorithmException if no Provider supports a
223 * KeyGeneratorSpi implementation for the
224 * specified algorithm.
225 *
226 * @see java.security.Provider
227 */
228 public static final KeyGenerator getInstance(String algorithm)
229 throws NoSuchAlgorithmException {
230 return new KeyGenerator(algorithm);
231 }
232
233 /**
234 * Returns a {@code KeyGenerator} object that generates secret keys
235 * for the specified algorithm.
236 *
237 * <p> A new KeyGenerator object encapsulating the
238 * KeyGeneratorSpi implementation from the specified provider
239 * is returned. The specified provider must be registered
240 * in the security provider list.
241 *
242 * <p> Note that the list of registered providers may be retrieved via
243 * the {@link Security#getProviders() Security.getProviders()} method.
244 *
245 * @param algorithm the standard name of the requested key algorithm.
246 * See the KeyGenerator section in the <a href=
247 * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyGenerator">
248 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
249 * for information about standard algorithm names.
250 *
251 * @param provider the name of the provider.
252 *
253 * @return the new {@code KeyGenerator} object.
254 *
255 * @exception NullPointerException if the specified algorithm is null.
256 *
257 * @exception NoSuchAlgorithmException if a KeyGeneratorSpi
258 * implementation for the specified algorithm is not
259 * available from the specified provider.
260 *
261 * @exception NoSuchProviderException if the specified provider is not
262 * registered in the security provider list.
263 *
264 * @exception IllegalArgumentException if the {@code provider}
265 * is null or empty.
266 *
267 * @see java.security.Provider
268 */
269 public static final KeyGenerator getInstance(String algorithm,
270 String provider) throws NoSuchAlgorithmException,
271 NoSuchProviderException {
272 Instance instance = JceSecurity.getInstance("KeyGenerator",
273 KeyGeneratorSpi.class, algorithm, provider);
274 return new KeyGenerator((KeyGeneratorSpi)instance.impl,
275 instance.provider, algorithm);
276 }
277
278 /**
279 * Returns a {@code KeyGenerator} object that generates secret keys
280 * for the specified algorithm.
281 *
282 * <p> A new KeyGenerator object encapsulating the
283 * KeyGeneratorSpi implementation from the specified Provider
284 * object is returned. Note that the specified Provider object
285 * does not have to be registered in the provider list.
286 *
287 * @param algorithm the standard name of the requested key algorithm.
288 * See the KeyGenerator section in the <a href=
289 * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyGenerator">
290 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
291 * for information about standard algorithm names.
292 *
293 * @param provider the provider.
294 *
295 * @return the new {@code KeyGenerator} object.
296 *
297 * @exception NullPointerException if the specified algorithm is null.
298 *
299 * @exception NoSuchAlgorithmException if a KeyGeneratorSpi
300 * implementation for the specified algorithm is not available
301 * from the specified Provider object.
302 *
303 * @exception IllegalArgumentException if the {@code provider}
304 * is null.
305 *
306 * @see java.security.Provider
307 */
308 public static final KeyGenerator getInstance(String algorithm,
309 Provider provider) throws NoSuchAlgorithmException {
310 Instance instance = JceSecurity.getInstance("KeyGenerator",
311 KeyGeneratorSpi.class, algorithm, provider);
312 return new KeyGenerator((KeyGeneratorSpi)instance.impl,
313 instance.provider, algorithm);
314 }
315
316 /**
317 * Returns the provider of this {@code KeyGenerator} object.
318 *
319 * @return the provider of this {@code KeyGenerator} object
320 */
321 public final Provider getProvider() {
322 synchronized (lock) {
323 disableFailover();
324 return provider;
325 }
326 }
327
328 /**
329 * Update the active spi of this class and return the next
330 * implementation for failover. If no more implementations are
331 * available, this method returns null. However, the active spi of
332 * this class is never set to null.
333 */
334 private KeyGeneratorSpi nextSpi(KeyGeneratorSpi oldSpi,
335 boolean reinit) {
336 synchronized (lock) {
337 // somebody else did a failover concurrently
338 // try that spi now
339 if ((oldSpi != null) && (oldSpi != spi)) {
340 return spi;
341 }
342 if (serviceIterator == null) {
343 return null;
344 }
345 while (serviceIterator.hasNext()) {
346 Service s = serviceIterator.next();
347 if (JceSecurity.canUseProvider(s.getProvider()) == false) {
348 continue;
349 }
350 try {
351 Object inst = s.newInstance(null);
352 // ignore non-spis
353 if (inst instanceof KeyGeneratorSpi == false) {
354 continue;
355 }
356 KeyGeneratorSpi spi = (KeyGeneratorSpi)inst;
357 if (reinit) {
358 if (initType == I_SIZE) {
359 spi.engineInit(initKeySize, initRandom);
360 } else if (initType == I_PARAMS) {
361 spi.engineInit(initParams, initRandom);
362 } else if (initType == I_RANDOM) {
363 spi.engineInit(initRandom);
364 } else if (initType != I_NONE) {
365 throw new AssertionError
366 ("KeyGenerator initType: " + initType);
367 }
368 }
369 provider = s.getProvider();
370 this.spi = spi;
371 return spi;
372 } catch (Exception e) {
373 // ignore
374 }
375 }
376 disableFailover();
377 return null;
378 }
379 }
380
381 void disableFailover() {
382 serviceIterator = null;
383 initType = 0;
384 initParams = null;
385 initRandom = null;
386 }
387
388 /**
389 * Initializes this key generator.
390 *
391 * @param random the source of randomness for this generator
392 */
393 public final void init(SecureRandom random) {
394 if (serviceIterator == null) {
395 spi.engineInit(random);
396 return;
397 }
398 RuntimeException failure = null;
399 KeyGeneratorSpi mySpi = spi;
400 do {
401 try {
402 mySpi.engineInit(random);
403 initType = I_RANDOM;
404 initKeySize = 0;
405 initParams = null;
406 initRandom = random;
407 return;
408 } catch (RuntimeException e) {
409 if (failure == null) {
410 failure = e;
411 }
412 mySpi = nextSpi(mySpi, false);
413 }
414 } while (mySpi != null);
415 throw failure;
416 }
417
418 /**
419 * Initializes this key generator with the specified parameter set.
420 *
421 * <p> If this key generator requires any random bytes, it will get them
422 * using the
423 * {@link java.security.SecureRandom}
424 * implementation of the highest-priority installed
425 * provider as the source of randomness.
426 * (If none of the installed providers supply an implementation of
427 * SecureRandom, a system-provided source of randomness will be used.)
428 *
429 * @param params the key generation parameters
430 *
431 * @exception InvalidAlgorithmParameterException if the given parameters
432 * are inappropriate for this key generator
433 */
434 public final void init(AlgorithmParameterSpec params)
435 throws InvalidAlgorithmParameterException
436 {
437 init(params, JceSecurity.RANDOM);
438 }
439
440 /**
441 * Initializes this key generator with the specified parameter
442 * set and a user-provided source of randomness.
443 *
444 * @param params the key generation parameters
445 * @param random the source of randomness for this key generator
446 *
447 * @exception InvalidAlgorithmParameterException if {@code params} is
448 * inappropriate for this key generator
449 */
450 public final void init(AlgorithmParameterSpec params, SecureRandom random)
451 throws InvalidAlgorithmParameterException
452 {
453 if (serviceIterator == null) {
454 spi.engineInit(params, random);
455 return;
456 }
457 Exception failure = null;
458 KeyGeneratorSpi mySpi = spi;
459 do {
460 try {
461 mySpi.engineInit(params, random);
462 initType = I_PARAMS;
463 initKeySize = 0;
464 initParams = params;
465 initRandom = random;
466 return;
467 } catch (Exception e) {
468 if (failure == null) {
469 failure = e;
470 }
471 mySpi = nextSpi(mySpi, false);
472 }
473 } while (mySpi != null);
474 if (failure instanceof InvalidAlgorithmParameterException) {
475 throw (InvalidAlgorithmParameterException)failure;
476 }
477 if (failure instanceof RuntimeException) {
478 throw (RuntimeException)failure;
479 }
480 throw new InvalidAlgorithmParameterException("init() failed", failure);
481 }
482
483 /**
484 * Initializes this key generator for a certain keysize.
485 *
486 * <p> If this key generator requires any random bytes, it will get them
487 * using the
488 * {@link java.security.SecureRandom}
489 * implementation of the highest-priority installed
490 * provider as the source of randomness.
491 * (If none of the installed providers supply an implementation of
492 * SecureRandom, a system-provided source of randomness will be used.)
493 *
494 * @param keysize the keysize. This is an algorithm-specific metric,
495 * specified in number of bits.
496 *
497 * @exception InvalidParameterException if the keysize is wrong or not
498 * supported.
499 */
500 public final void init(int keysize) {
501 init(keysize, JceSecurity.RANDOM);
502 }
503
504 /**
505 * Initializes this key generator for a certain keysize, using a
506 * user-provided source of randomness.
507 *
508 * @param keysize the keysize. This is an algorithm-specific metric,
509 * specified in number of bits.
510 * @param random the source of randomness for this key generator
511 *
512 * @exception InvalidParameterException if the keysize is wrong or not
513 * supported.
514 */
515 public final void init(int keysize, SecureRandom random) {
516 if (serviceIterator == null) {
517 spi.engineInit(keysize, random);
518 return;
519 }
520 RuntimeException failure = null;
521 KeyGeneratorSpi mySpi = spi;
522 do {
523 try {
524 mySpi.engineInit(keysize, random);
525 initType = I_SIZE;
526 initKeySize = keysize;
527 initParams = null;
528 initRandom = random;
529 return;
530 } catch (RuntimeException e) {
531 if (failure == null) {
532 failure = e;
533 }
534 mySpi = nextSpi(mySpi, false);
535 }
536 } while (mySpi != null);
537 throw failure;
538 }
539
540 /**
541 * Generates a secret key.
542 *
543 * @return the new key
544 */
545 public final SecretKey generateKey() {
546 if (serviceIterator == null) {
547 return spi.engineGenerateKey();
548 }
549 RuntimeException failure = null;
550 KeyGeneratorSpi mySpi = spi;
551 do {
552 try {
553 return mySpi.engineGenerateKey();
554 } catch (RuntimeException e) {
555 if (failure == null) {
556 failure = e;
557 }
558 mySpi = nextSpi(mySpi, true);
559 }
560 } while (mySpi != null);
561 throw failure;
562 }
563 }