1 /*
2 * Copyright (c) 1997, 2016, 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}
208 * {@link Security#getProperty(String) Security} property to determine
209 * the preferred provider order for the specified algorithm. This
210 * may be different than the order of providers returned by
211 * {@link Security#getProviders() Security.getProviders()}.
212 *
213 * @param algorithm the standard name of the requested key algorithm.
214 * See the KeyGenerator section in the <a href=
215 * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyGenerator">
216 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
217 * for information about standard algorithm names.
218 *
219 * @return the new {@code KeyGenerator} object.
220 *
221 * @exception NullPointerException if the specified algorithm is null.
222 *
223 * @exception NoSuchAlgorithmException if no Provider supports a
224 * KeyGeneratorSpi implementation for the
225 * specified algorithm.
226 *
227 * @see java.security.Provider
228 */
229 public static final KeyGenerator getInstance(String algorithm)
230 throws NoSuchAlgorithmException {
231 return new KeyGenerator(algorithm);
232 }
233
234 /**
235 * Returns a {@code KeyGenerator} object that generates secret keys
236 * for the specified algorithm.
237 *
238 * <p> A new KeyGenerator object encapsulating the
239 * KeyGeneratorSpi implementation from the specified provider
240 * is returned. The specified provider must be registered
241 * in the security provider list.
242 *
243 * <p> Note that the list of registered providers may be retrieved via
244 * the {@link Security#getProviders() Security.getProviders()} method.
245 *
246 * @param algorithm the standard name of the requested key algorithm.
247 * See the KeyGenerator section in the <a href=
248 * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyGenerator">
249 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
250 * for information about standard algorithm names.
251 *
252 * @param provider the name of the provider.
253 *
254 * @return the new {@code KeyGenerator} object.
255 *
256 * @exception NullPointerException if the specified algorithm is null.
257 *
258 * @exception NoSuchAlgorithmException if a KeyGeneratorSpi
259 * implementation for the specified algorithm is not
260 * available from the specified provider.
261 *
262 * @exception NoSuchProviderException if the specified provider is not
263 * registered in the security provider list.
264 *
265 * @exception IllegalArgumentException if the {@code provider}
266 * is null or empty.
267 *
268 * @see java.security.Provider
269 */
270 public static final KeyGenerator getInstance(String algorithm,
271 String provider) throws NoSuchAlgorithmException,
272 NoSuchProviderException {
273 Instance instance = JceSecurity.getInstance("KeyGenerator",
274 KeyGeneratorSpi.class, algorithm, provider);
275 return new KeyGenerator((KeyGeneratorSpi)instance.impl,
276 instance.provider, algorithm);
277 }
278
279 /**
280 * Returns a {@code KeyGenerator} object that generates secret keys
281 * for the specified algorithm.
282 *
283 * <p> A new KeyGenerator object encapsulating the
284 * KeyGeneratorSpi implementation from the specified Provider
285 * object is returned. Note that the specified Provider object
286 * does not have to be registered in the provider list.
287 *
288 * @param algorithm the standard name of the requested key algorithm.
289 * See the KeyGenerator section in the <a href=
290 * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyGenerator">
291 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
292 * for information about standard algorithm names.
293 *
294 * @param provider the provider.
295 *
296 * @return the new {@code KeyGenerator} object.
297 *
298 * @exception NullPointerException if the specified algorithm is null.
299 *
300 * @exception NoSuchAlgorithmException if a KeyGeneratorSpi
301 * implementation for the specified algorithm is not available
302 * from the specified Provider object.
303 *
304 * @exception IllegalArgumentException if the {@code provider}
305 * is null.
306 *
307 * @see java.security.Provider
308 */
309 public static final KeyGenerator getInstance(String algorithm,
310 Provider provider) throws NoSuchAlgorithmException {
311 Instance instance = JceSecurity.getInstance("KeyGenerator",
312 KeyGeneratorSpi.class, algorithm, provider);
313 return new KeyGenerator((KeyGeneratorSpi)instance.impl,
314 instance.provider, algorithm);
315 }
316
317 /**
318 * Returns the provider of this {@code KeyGenerator} object.
319 *
320 * @return the provider of this {@code KeyGenerator} object
321 */
322 public final Provider getProvider() {
323 synchronized (lock) {
324 disableFailover();
325 return provider;
326 }
327 }
328
329 /**
330 * Update the active spi of this class and return the next
331 * implementation for failover. If no more implementations are
332 * available, this method returns null. However, the active spi of
333 * this class is never set to null.
334 */
335 private KeyGeneratorSpi nextSpi(KeyGeneratorSpi oldSpi,
336 boolean reinit) {
337 synchronized (lock) {
338 // somebody else did a failover concurrently
339 // try that spi now
340 if ((oldSpi != null) && (oldSpi != spi)) {
341 return spi;
342 }
343 if (serviceIterator == null) {
344 return null;
345 }
346 while (serviceIterator.hasNext()) {
347 Service s = serviceIterator.next();
348 if (JceSecurity.canUseProvider(s.getProvider()) == false) {
349 continue;
350 }
351 try {
352 Object inst = s.newInstance(null);
353 // ignore non-spis
354 if (inst instanceof KeyGeneratorSpi == false) {
355 continue;
356 }
357 KeyGeneratorSpi spi = (KeyGeneratorSpi)inst;
358 if (reinit) {
359 if (initType == I_SIZE) {
360 spi.engineInit(initKeySize, initRandom);
361 } else if (initType == I_PARAMS) {
362 spi.engineInit(initParams, initRandom);
363 } else if (initType == I_RANDOM) {
364 spi.engineInit(initRandom);
365 } else if (initType != I_NONE) {
366 throw new AssertionError
367 ("KeyGenerator initType: " + initType);
368 }
369 }
370 provider = s.getProvider();
371 this.spi = spi;
372 return spi;
373 } catch (Exception e) {
374 // ignore
375 }
376 }
377 disableFailover();
378 return null;
379 }
380 }
381
382 void disableFailover() {
383 serviceIterator = null;
384 initType = 0;
385 initParams = null;
386 initRandom = null;
387 }
388
389 /**
390 * Initializes this key generator.
391 *
392 * @param random the source of randomness for this generator
393 */
394 public final void init(SecureRandom random) {
395 if (serviceIterator == null) {
396 spi.engineInit(random);
397 return;
398 }
399 RuntimeException failure = null;
400 KeyGeneratorSpi mySpi = spi;
401 do {
402 try {
403 mySpi.engineInit(random);
404 initType = I_RANDOM;
405 initKeySize = 0;
406 initParams = null;
407 initRandom = random;
408 return;
409 } catch (RuntimeException e) {
410 if (failure == null) {
411 failure = e;
412 }
413 mySpi = nextSpi(mySpi, false);
414 }
415 } while (mySpi != null);
416 throw failure;
417 }
418
419 /**
420 * Initializes this key generator with the specified parameter set.
421 *
422 * <p> If this key generator requires any random bytes, it will get them
423 * using the
424 * {@link java.security.SecureRandom}
425 * implementation of the highest-priority installed
426 * provider as the source of randomness.
427 * (If none of the installed providers supply an implementation of
428 * SecureRandom, a system-provided source of randomness will be used.)
429 *
430 * @param params the key generation parameters
431 *
432 * @exception InvalidAlgorithmParameterException if the given parameters
433 * are inappropriate for this key generator
434 */
435 public final void init(AlgorithmParameterSpec params)
436 throws InvalidAlgorithmParameterException
437 {
438 init(params, JceSecurity.RANDOM);
439 }
440
441 /**
442 * Initializes this key generator with the specified parameter
443 * set and a user-provided source of randomness.
444 *
445 * @param params the key generation parameters
446 * @param random the source of randomness for this key generator
447 *
448 * @exception InvalidAlgorithmParameterException if {@code params} is
449 * inappropriate for this key generator
450 */
451 public final void init(AlgorithmParameterSpec params, SecureRandom random)
452 throws InvalidAlgorithmParameterException
453 {
454 if (serviceIterator == null) {
455 spi.engineInit(params, random);
456 return;
457 }
458 Exception failure = null;
459 KeyGeneratorSpi mySpi = spi;
460 do {
461 try {
462 mySpi.engineInit(params, random);
463 initType = I_PARAMS;
464 initKeySize = 0;
465 initParams = params;
466 initRandom = random;
467 return;
468 } catch (Exception e) {
469 if (failure == null) {
470 failure = e;
471 }
472 mySpi = nextSpi(mySpi, false);
473 }
474 } while (mySpi != null);
475 if (failure instanceof InvalidAlgorithmParameterException) {
476 throw (InvalidAlgorithmParameterException)failure;
477 }
478 if (failure instanceof RuntimeException) {
479 throw (RuntimeException)failure;
480 }
481 throw new InvalidAlgorithmParameterException("init() failed", failure);
482 }
483
484 /**
485 * Initializes this key generator for a certain keysize.
486 *
487 * <p> If this key generator requires any random bytes, it will get them
488 * using the
489 * {@link java.security.SecureRandom}
490 * implementation of the highest-priority installed
491 * provider as the source of randomness.
492 * (If none of the installed providers supply an implementation of
493 * SecureRandom, a system-provided source of randomness will be used.)
494 *
495 * @param keysize the keysize. This is an algorithm-specific metric,
496 * specified in number of bits.
497 *
498 * @exception InvalidParameterException if the keysize is wrong or not
499 * supported.
500 */
501 public final void init(int keysize) {
502 init(keysize, JceSecurity.RANDOM);
503 }
504
505 /**
506 * Initializes this key generator for a certain keysize, using a
507 * user-provided source of randomness.
508 *
509 * @param keysize the keysize. This is an algorithm-specific metric,
510 * specified in number of bits.
511 * @param random the source of randomness for this key generator
512 *
513 * @exception InvalidParameterException if the keysize is wrong or not
514 * supported.
515 */
516 public final void init(int keysize, SecureRandom random) {
517 if (serviceIterator == null) {
518 spi.engineInit(keysize, random);
519 return;
520 }
521 RuntimeException failure = null;
522 KeyGeneratorSpi mySpi = spi;
523 do {
524 try {
525 mySpi.engineInit(keysize, random);
526 initType = I_SIZE;
527 initKeySize = keysize;
528 initParams = null;
529 initRandom = random;
530 return;
531 } catch (RuntimeException e) {
532 if (failure == null) {
533 failure = e;
534 }
535 mySpi = nextSpi(mySpi, false);
536 }
537 } while (mySpi != null);
538 throw failure;
539 }
540
541 /**
542 * Generates a secret key.
543 *
544 * @return the new key
545 */
546 public final SecretKey generateKey() {
547 if (serviceIterator == null) {
548 return spi.engineGenerateKey();
549 }
550 RuntimeException failure = null;
551 KeyGeneratorSpi mySpi = spi;
552 do {
553 try {
554 return mySpi.engineGenerateKey();
555 } catch (RuntimeException e) {
556 if (failure == null) {
557 failure = e;
558 }
559 mySpi = nextSpi(mySpi, true);
560 }
561 } while (mySpi != null);
562 throw failure;
563 }
564 }