1 /*
2 * Copyright (c) 1996, 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 java.security;
27
28 import java.util.*;
29 import java.util.regex.*;
30
31 import java.security.Provider.Service;
32
33 import sun.security.jca.*;
34 import sun.security.jca.GetInstance.Instance;
35 import sun.security.util.Debug;
36
37 /**
38 * This class provides a cryptographically strong random number
39 * generator (RNG).
40 *
41 * <p>A cryptographically strong random number minimally complies with the
42 * statistical random number generator tests specified in
43 * <a href="http://csrc.nist.gov/publications/fips/fips140-2/fips1402.pdf">
44 * <i>FIPS 140-2, Security Requirements for Cryptographic Modules</i></a>,
45 * section 4.9.1.
46 * Additionally, {@code SecureRandom} must produce non-deterministic output.
47 * Therefore any seed material passed to a {@code SecureRandom} object must be
48 * unpredictable, and all {@code SecureRandom} output sequences must be
49 * cryptographically strong, as described in
50 * <a href="http://tools.ietf.org/html/rfc4086">
51 * <i>RFC 4086: Randomness Requirements for Security</i></a>.
52 *
53 * <p> Many {@code SecureRandom} implementations are in the form of a
54 * pseudo-random number generator (PRNG, also known as deterministic random
55 * bits generator or DRBG), which means they use a deterministic algorithm
56 * to produce a pseudo-random sequence from a random seed.
57 * Other implementations may produce true random numbers,
58 * and yet others may use a combination of both techniques.
59 *
60 * <p>A caller obtains a {@code SecureRandom} instance via the
61 * no-argument constructor or one of the {@code getInstance} methods.
62 * For example:
63 *
64 * <blockquote><pre>
65 * SecureRandom r1 = new SecureRandom();
66 * SecureRandom r2 = SecureRandom.getInstance("NativePRNG");
67 * SecureRandom r3 = SecureRandom("DRBG",
68 * DrbgParameters.Instantiation(128, RESEED_ONLY, null));</pre>
69 * </blockquote>
70 *
71 * <p> The third statement above returns a {@code SecureRandom} object of the
72 * specific algorithm supporting the specific instantiate parameters. The
73 * implementation's effective instantiated parameters must match this minimum
74 * request but is not necessarily the same. For example, even if the request
75 * does not require a certain feature, the actual instantiation can provide
76 * the feature. An implementation may lazily instantiate a {@code SecureRandom}
77 * until it's actually used, but the effective instantiate parameters must be
78 * determined right after it's created and {@link #getParameters()} should
79 * always return the same result unchanged.
80 *
81 * <p> Typical callers of {@code SecureRandom} invoke the following methods
82 * to retrieve random bytes:
83 *
84 * <blockquote><pre>
85 * SecureRandom random = new SecureRandom();
86 * byte[] bytes = new byte[20];
87 * random.nextBytes(bytes);</pre>
88 * </blockquote>
89 *
90 * <p> Callers may also invoke the {@link #generateSeed} method
91 * to generate a given number of seed bytes (to seed other random number
92 * generators, for example):
93 *
94 * <blockquote><pre>
95 * byte[] seed = random.generateSeed(20);</pre>
96 * </blockquote>
97 *
98 * <p> A newly created PRNG {@code SecureRandom} object is not seeded (except
99 * if it is created by {@link #SecureRandom(byte[])}). The first call to
100 * {@code nextBytes} will force it to seed itself from an implementation-
101 * specific entropy source. This self-seeding will not occur if {@code setSeed}
102 * was previously called.
103 *
104 * <p> A {@code SecureRandom} can be reseeded at any time by calling the
105 * {@code reseed} or {@code setSeed} method. The {@code reseed} method
106 * reads entropy input from its entropy source to reseed itself.
107 * The {@code setSeed} method requires the caller to provide the seed.
108 *
109 * <p> Please note that {@code reseed} may not be supported by all
110 * {@code SecureRandom} implementations.
111 *
112 * <p> Some {@code SecureRandom} implementations may accept a
113 * {@link SecureRandomParameters} parameter in its
114 * {@link #nextBytes(byte[], SecureRandomParameters)} and
115 * {@link #reseed(SecureRandomParameters)} methods to further
116 * control the behavior of the methods.
117 *
118 * <p> Note: Depending on the implementation, the {@code generateSeed},
119 * {@code reseed} and {@code nextBytes} methods may block as entropy is being
120 * gathered, for example, if the entropy source is /dev/random on various
121 * Unix-like operating systems.
122 *
123 * @see java.security.SecureRandomSpi
124 * @see java.util.Random
125 *
126 * @author Benjamin Renaud
127 * @author Josh Bloch
128 */
129
130 public class SecureRandom extends java.util.Random {
131
132 private static final Debug pdebug =
133 Debug.getInstance("provider", "Provider");
134 private static final boolean skipDebug =
135 Debug.isOn("engine=") && !Debug.isOn("securerandom");
136
137 /**
138 * The provider.
139 *
140 * @serial
141 * @since 1.2
142 */
143 private Provider provider = null;
144
145 /**
146 * The provider implementation.
147 *
148 * @serial
149 * @since 1.2
150 */
151 private SecureRandomSpi secureRandomSpi = null;
152
153 /*
154 * The algorithm name of null if unknown.
155 *
156 * @serial
157 * @since 1.5
158 */
159 private String algorithm;
160
161 // Seed Generator
162 private static volatile SecureRandom seedGenerator;
163
164 /**
165 * Constructs a secure random number generator (RNG) implementing the
166 * default random number algorithm.
167 *
168 * <p> This constructor traverses the list of registered security Providers,
169 * starting with the most preferred Provider.
170 * A new {@code SecureRandom} object encapsulating the
171 * {@code SecureRandomSpi} implementation from the first
172 * Provider that supports a {@code SecureRandom} (RNG) algorithm is returned.
173 * If none of the Providers support a RNG algorithm,
174 * then an implementation-specific default is returned.
175 *
176 * <p> Note that the list of registered providers may be retrieved via
177 * the {@link Security#getProviders() Security.getProviders()} method.
178 *
179 * <p> See the {@code SecureRandom} section in the <a href=
180 * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom">
181 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
182 * for information about standard RNG algorithm names.
183 */
184 public SecureRandom() {
185 /*
186 * This call to our superclass constructor will result in a call
187 * to our own {@code setSeed} method, which will return
188 * immediately when it is passed zero.
189 */
190 super(0);
191 getDefaultPRNG(false, null);
192 }
193
194 /**
195 * Constructs a secure random number generator (RNG) implementing the
196 * default random number algorithm.
197 * The {@code SecureRandom} instance is seeded with the specified seed bytes.
198 *
199 * <p> This constructor traverses the list of registered security Providers,
200 * starting with the most preferred Provider.
201 * A new {@code SecureRandom} object encapsulating the
202 * {@code SecureRandomSpi} implementation from the first
203 * Provider that supports a {@code SecureRandom} (RNG) algorithm is returned.
204 * If none of the Providers support a RNG algorithm,
205 * then an implementation-specific default is returned.
206 *
207 * <p> Note that the list of registered providers may be retrieved via
208 * the {@link Security#getProviders() Security.getProviders()} method.
209 *
210 * <p> See the {@code SecureRandom} section in the <a href=
211 * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom">
212 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
213 * for information about standard RNG algorithm names.
214 *
215 * @param seed the seed.
216 */
217 public SecureRandom(byte[] seed) {
218 super(0);
219 getDefaultPRNG(true, seed);
220 }
221
222 private void getDefaultPRNG(boolean setSeed, byte[] seed) {
223 String prng = getPrngAlgorithm();
224 if (prng == null) {
225 // bummer, get the SUN implementation
226 prng = "SHA1PRNG";
227 this.secureRandomSpi = new sun.security.provider.SecureRandom();
228 this.provider = Providers.getSunProvider();
229 if (setSeed) {
230 this.secureRandomSpi.engineSetSeed(seed);
231 }
232 } else {
233 try {
234 SecureRandom random = SecureRandom.getInstance(prng);
235 this.secureRandomSpi = random.getSecureRandomSpi();
236 this.provider = random.getProvider();
237 if (setSeed) {
238 this.secureRandomSpi.engineSetSeed(seed);
239 }
240 } catch (NoSuchAlgorithmException nsae) {
241 // never happens, because we made sure the algorithm exists
242 throw new RuntimeException(nsae);
243 }
244 }
245 // JDK 1.1 based implementations subclass SecureRandom instead of
246 // SecureRandomSpi. They will also go through this code path because
247 // they must call a SecureRandom constructor as it is their superclass.
248 // If we are dealing with such an implementation, do not set the
249 // algorithm value as it would be inaccurate.
250 if (getClass() == SecureRandom.class) {
251 this.algorithm = prng;
252 }
253 }
254
255 /**
256 * Creates a {@code SecureRandom} object.
257 *
258 * @param secureRandomSpi the {@code SecureRandom} implementation.
259 * @param provider the provider.
260 */
261 protected SecureRandom(SecureRandomSpi secureRandomSpi,
262 Provider provider) {
263 this(secureRandomSpi, provider, null);
264 }
265
266 private SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider,
267 String algorithm) {
268 super(0);
269 this.secureRandomSpi = secureRandomSpi;
270 this.provider = provider;
271 this.algorithm = algorithm;
272
273 if (!skipDebug && pdebug != null) {
274 pdebug.println("SecureRandom." + algorithm +
275 " algorithm from: " + this.provider.getName());
276 }
277 }
278
279 /**
280 * Returns a {@code SecureRandom} object that implements the specified
281 * Random Number Generator (RNG) algorithm.
282 *
283 * <p> This method traverses the list of registered security Providers,
284 * starting with the most preferred Provider.
285 * A new {@code SecureRandom} object encapsulating the
286 * {@code SecureRandomSpi} implementation from the first
287 * Provider that supports the specified algorithm is returned.
288 *
289 * <p> Note that the list of registered providers may be retrieved via
290 * the {@link Security#getProviders() Security.getProviders()} method.
291 *
292 * @implNote
293 * The JDK Reference Implementation additionally uses the
294 * {@code jdk.security.provider.preferred}
295 * {@link Security#getProperty(String) Security} property to determine
296 * the preferred provider order for the specified algorithm. This
297 * may be different than the order of providers returned by
298 * {@link Security#getProviders() Security.getProviders()}.
299 *
300 * @param algorithm the name of the RNG algorithm.
301 * See the {@code SecureRandom} section in the <a href=
302 * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom">
303 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
304 * for information about standard RNG algorithm names.
305 *
306 * @return the new {@code SecureRandom} object.
307 *
308 * @exception NoSuchAlgorithmException if no Provider supports a
309 * {@code SecureRandomSpi} implementation for the
310 * specified algorithm.
311 *
312 * @see Provider
313 *
314 * @since 1.2
315 */
316 public static SecureRandom getInstance(String algorithm)
317 throws NoSuchAlgorithmException {
318 Instance instance = GetInstance.getInstance("SecureRandom",
319 SecureRandomSpi.class, algorithm);
320 return new SecureRandom((SecureRandomSpi)instance.impl,
321 instance.provider, algorithm);
322 }
323
324 /**
325 * Returns a {@code SecureRandom} object that implements the specified
326 * Random Number Generator (RNG) algorithm.
327 *
328 * <p> A new {@code SecureRandom} object encapsulating the
329 * {@code SecureRandomSpi} implementation from the specified provider
330 * is returned. The specified provider must be registered
331 * in the security provider list.
332 *
333 * <p> Note that the list of registered providers may be retrieved via
334 * the {@link Security#getProviders() Security.getProviders()} method.
335 *
336 * @param algorithm the name of the RNG algorithm.
337 * See the {@code SecureRandom} section in the <a href=
338 * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom">
339 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
340 * for information about standard RNG algorithm names.
341 *
342 * @param provider the name of the provider.
343 *
344 * @return the new {@code SecureRandom} object.
345 *
346 * @throws NoSuchAlgorithmException if a {@code SecureRandomSpi}
347 * implementation for the specified algorithm is not
348 * available from the specified provider.
349 *
350 * @throws NoSuchProviderException if the specified provider is not
351 * registered in the security provider list.
352 *
353 * @throws IllegalArgumentException if the provider name is null
354 * or empty.
355 *
356 * @see Provider
357 *
358 * @since 1.2
359 */
360 public static SecureRandom getInstance(String algorithm, String provider)
361 throws NoSuchAlgorithmException, NoSuchProviderException {
362 Instance instance = GetInstance.getInstance("SecureRandom",
363 SecureRandomSpi.class, algorithm, provider);
364 return new SecureRandom((SecureRandomSpi)instance.impl,
365 instance.provider, algorithm);
366 }
367
368 /**
369 * Returns a {@code SecureRandom} object that implements the specified
370 * Random Number Generator (RNG) algorithm.
371 *
372 * <p> A new {@code SecureRandom} object encapsulating the
373 * {@code SecureRandomSpi} implementation from the specified {@code Provider}
374 * object is returned. Note that the specified {@code Provider} object
375 * does not have to be registered in the provider list.
376 *
377 * @param algorithm the name of the RNG algorithm.
378 * See the {@code SecureRandom} section in the <a href=
379 * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom">
380 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
381 * for information about standard RNG algorithm names.
382 *
383 * @param provider the provider.
384 *
385 * @return the new {@code SecureRandom} object.
386 *
387 * @throws NoSuchAlgorithmException if a {@code SecureRandomSpi}
388 * implementation for the specified algorithm is not available
389 * from the specified {@code Provider} object.
390 *
391 * @throws IllegalArgumentException if the specified provider is null.
392 *
393 * @see Provider
394 *
395 * @since 1.4
396 */
397 public static SecureRandom getInstance(String algorithm,
398 Provider provider) throws NoSuchAlgorithmException {
399 Instance instance = GetInstance.getInstance("SecureRandom",
400 SecureRandomSpi.class, algorithm, provider);
401 return new SecureRandom((SecureRandomSpi)instance.impl,
402 instance.provider, algorithm);
403 }
404
405 /**
406 * Returns a {@code SecureRandom} object that implements the specified
407 * Random Number Generator (RNG) algorithm and supports the specified
408 * {@code SecureRandomParameters} request.
409 *
410 * <p> This method traverses the list of registered security Providers,
411 * starting with the most preferred Provider.
412 * A new {@code SecureRandom} object encapsulating the
413 * {@code SecureRandomSpi} implementation from the first
414 * Provider that supports the specified algorithm and the specified
415 * {@code SecureRandomParameters} is returned.
416 *
417 * <p> Note that the list of registered providers may be retrieved via
418 * the {@link Security#getProviders() Security.getProviders()} method.
419 *
420 * @implNote
421 * The JDK Reference Implementation additionally uses the
422 * {@code jdk.security.provider.preferred} property to determine
423 * the preferred provider order for the specified algorithm. This
424 * may be different than the order of providers returned by
425 * {@link Security#getProviders() Security.getProviders()}.
426 *
427 * @param algorithm the name of the RNG algorithm.
428 * See the {@code SecureRandom} section in the <a href=
429 * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom">
430 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
431 * for information about standard RNG algorithm names.
432 *
433 * @param params the {@code SecureRandomParameters}
434 * the newly created {@code SecureRandom} object must support.
435 *
436 * @return the new {@code SecureRandom} object.
437 *
438 * @throws NoSuchAlgorithmException if no Provider supports a
439 * {@code SecureRandomSpi} implementation for the specified
440 * algorithm and parameters.
441 *
442 * @throws IllegalArgumentException if the specified params is null.
443 *
444 * @see Provider
445 *
446 * @since 9
447 */
448 public static SecureRandom getInstance(
449 String algorithm, SecureRandomParameters params)
450 throws NoSuchAlgorithmException {
451 if (params == null) {
452 throw new IllegalArgumentException("params cannot be null");
453 }
454 Instance instance = GetInstance.getInstance("SecureRandom",
455 SecureRandomSpi.class, algorithm, params);
456 return new SecureRandom((SecureRandomSpi)instance.impl,
457 instance.provider, algorithm);
458 }
459
460 /**
461 * Returns a {@code SecureRandom} object that implements the specified
462 * Random Number Generator (RNG) algorithm and supports the specified
463 * {@code SecureRandomParameters} request.
464 *
465 * <p> A new {@code SecureRandom} object encapsulating the
466 * {@code SecureRandomSpi} implementation from the specified provider
467 * is returned. The specified provider must be registered
468 * in the security provider list.
469 *
470 * <p> Note that the list of registered providers may be retrieved via
471 * the {@link Security#getProviders() Security.getProviders()} method.
472 *
473 * @param algorithm the name of the RNG algorithm.
474 * See the {@code SecureRandom} section in the <a href=
475 * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom">
476 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
477 * for information about standard RNG algorithm names.
478 *
479 * @param params the {@code SecureRandomParameters}
480 * the newly created {@code SecureRandom} object must support.
481 *
482 * @param provider the name of the provider.
483 *
484 * @return the new {@code SecureRandom} object.
485 *
486 * @throws NoSuchAlgorithmException if the specified provider does not
487 * support a {@code SecureRandomSpi} implementation for the
488 * specified algorithm and parameters.
489 *
490 * @throws NoSuchProviderException if the specified provider is not
491 * registered in the security provider list.
492 *
493 * @throws IllegalArgumentException if the provider name is null
494 * or empty, or params is null.
495 *
496 * @see Provider
497 *
498 * @since 9
499 */
500 public static SecureRandom getInstance(String algorithm,
501 SecureRandomParameters params, String provider)
502 throws NoSuchAlgorithmException, NoSuchProviderException {
503 if (params == null) {
504 throw new IllegalArgumentException("params cannot be null");
505 }
506 Instance instance = GetInstance.getInstance("SecureRandom",
507 SecureRandomSpi.class, algorithm, params, provider);
508 return new SecureRandom((SecureRandomSpi)instance.impl,
509 instance.provider, algorithm);
510 }
511
512 /**
513 * Returns a {@code SecureRandom} object that implements the specified
514 * Random Number Generator (RNG) algorithm and supports the specified
515 * {@code SecureRandomParameters} request.
516 *
517 * <p> A new {@code SecureRandom} object encapsulating the
518 * {@code SecureRandomSpi} implementation from the specified
519 * {@code Provider} object is returned. Note that the specified
520 * {@code Provider} object does not have to be registered in the
521 * provider list.
522 *
523 * @param algorithm the name of the RNG algorithm.
524 * See the {@code SecureRandom} section in the <a href=
525 * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom">
526 * Java Cryptography Architecture Standard Algorithm Name Documentation</a>
527 * for information about standard RNG algorithm names.
528 *
529 * @param params the {@code SecureRandomParameters}
530 * the newly created {@code SecureRandom} object must support.
531 *
532 * @param provider the provider.
533 *
534 * @return the new {@code SecureRandom} object.
535 *
536 * @throws NoSuchAlgorithmException if the specified provider does not
537 * support a {@code SecureRandomSpi} implementation for the
538 * specified algorithm and parameters.
539 *
540 * @throws IllegalArgumentException if the specified provider or params
541 * is null.
542 *
543 * @see Provider
544 *
545 * @since 9
546 */
547 public static SecureRandom getInstance(String algorithm,
548 SecureRandomParameters params, Provider provider)
549 throws NoSuchAlgorithmException {
550 if (params == null) {
551 throw new IllegalArgumentException("params cannot be null");
552 }
553 Instance instance = GetInstance.getInstance("SecureRandom",
554 SecureRandomSpi.class, algorithm, params, provider);
555 return new SecureRandom((SecureRandomSpi)instance.impl,
556 instance.provider, algorithm);
557 }
558
559 /**
560 * Returns the {@code SecureRandomSpi} of this {@code SecureRandom} object.
561 */
562 SecureRandomSpi getSecureRandomSpi() {
563 return secureRandomSpi;
564 }
565
566 /**
567 * Returns the provider of this {@code SecureRandom} object.
568 *
569 * @return the provider of this {@code SecureRandom} object.
570 */
571 public final Provider getProvider() {
572 return provider;
573 }
574
575 /**
576 * Returns the name of the algorithm implemented by this
577 * {@code SecureRandom} object.
578 *
579 * @return the name of the algorithm or {@code unknown}
580 * if the algorithm name cannot be determined.
581 * @since 1.5
582 */
583 public String getAlgorithm() {
584 return Objects.toString(algorithm, "unknown");
585 }
586
587 /**
588 * Returns a Human-readable string representation of this
589 * {@code SecureRandom}.
590 *
591 * @return the string representation
592 *
593 * @since 9
594 */
595 @Override
596 public String toString() {
597 return secureRandomSpi.toString();
598 }
599
600 /**
601 * Returns the effective {@link SecureRandomParameters} for this
602 * {@code SecureRandom} instance.
603 * <p>
604 * The returned value can be different from the
605 * {@code SecureRandomParameters} object passed into a {@code getInstance}
606 * method, but it cannot change during the lifetime of this
607 * {@code SecureRandom} object.
608 * <p>
609 * A caller can use the returned value to find out what features this
610 * {@code SecureRandom} supports.
611 *
612 * @return the effective {@link SecureRandomParameters} parameters,
613 * or {@code null} if no parameters were used.
614 *
615 * @since 9
616 * @see SecureRandomSpi
617 */
618 public SecureRandomParameters getParameters() {
619 return secureRandomSpi.engineGetParameters();
620 }
621
622 /**
623 * Reseeds this random object with the given seed. The seed supplements,
624 * rather than replaces, the existing seed. Thus, repeated calls are
625 * guaranteed never to reduce randomness.
626 * <p>
627 * A PRNG {@code SecureRandom} will not seed itself automatically if
628 * {@code setSeed} is called before any {@code nextBytes} or {@code reseed}
629 * calls. The caller should make sure that the {@code seed} argument
630 * contains enough entropy for the security of this {@code SecureRandom}.
631 *
632 * @param seed the seed.
633 *
634 * @see #getSeed
635 */
636 public synchronized void setSeed(byte[] seed) {
637 secureRandomSpi.engineSetSeed(seed);
638 }
639
640 /**
641 * Reseeds this random object, using the eight bytes contained
642 * in the given {@code long seed}. The given seed supplements,
643 * rather than replaces, the existing seed. Thus, repeated calls
644 * are guaranteed never to reduce randomness.
645 *
646 * <p>This method is defined for compatibility with
647 * {@code java.util.Random}.
648 *
649 * @param seed the seed.
650 *
651 * @see #getSeed
652 */
653 @Override
654 public void setSeed(long seed) {
655 /*
656 * Ignore call from super constructor (as well as any other calls
657 * unfortunate enough to be passing 0). It's critical that we
658 * ignore call from superclass constructor, as digest has not
659 * yet been initialized at that point.
660 */
661 if (seed != 0) {
662 this.secureRandomSpi.engineSetSeed(longToByteArray(seed));
663 }
664 }
665
666 /**
667 * Generates a user-specified number of random bytes.
668 *
669 * @param bytes the array to be filled in with random bytes.
670 */
671 @Override
672 public void nextBytes(byte[] bytes) {
673 secureRandomSpi.engineNextBytes(bytes);
674 }
675
676 /**
677 * Generates a user-specified number of random bytes with
678 * additional parameters.
679 *
680 * @param bytes the array to be filled in with random bytes
681 * @param params additional parameters
682 * @throws NullPointerException if {@code bytes} is null
683 * @throws UnsupportedOperationException if the underlying provider
684 * implementation has not overridden this method
685 * @throws IllegalArgumentException if {@code params} is {@code null},
686 * illegal or unsupported by this {@code SecureRandom}
687 *
688 * @since 9
689 */
690 public synchronized void nextBytes(
691 byte[] bytes, SecureRandomParameters params) {
692 if (params == null) {
693 throw new IllegalArgumentException("params cannot be null");
694 }
695 secureRandomSpi.engineNextBytes(Objects.requireNonNull(bytes), params);
696 }
697
698 /**
699 * Generates an integer containing the user-specified number of
700 * pseudo-random bits (right justified, with leading zeros). This
701 * method overrides a {@code java.util.Random} method, and serves
702 * to provide a source of random bits to all of the methods inherited
703 * from that class (for example, {@code nextInt},
704 * {@code nextLong}, and {@code nextFloat}).
705 *
706 * @param numBits number of pseudo-random bits to be generated, where
707 * {@code 0 <= numBits <= 32}.
708 *
709 * @return an {@code int} containing the user-specified number
710 * of pseudo-random bits (right justified, with leading zeros).
711 */
712 @Override
713 protected final int next(int numBits) {
714 int numBytes = (numBits+7)/8;
715 byte[] b = new byte[numBytes];
716 int next = 0;
717
718 nextBytes(b);
719 for (int i = 0; i < numBytes; i++) {
720 next = (next << 8) + (b[i] & 0xFF);
721 }
722
723 return next >>> (numBytes*8 - numBits);
724 }
725
726 /**
727 * Returns the given number of seed bytes, computed using the seed
728 * generation algorithm that this class uses to seed itself. This
729 * call may be used to seed other random number generators.
730 *
731 * <p>This method is only included for backwards compatibility.
732 * The caller is encouraged to use one of the alternative
733 * {@code getInstance} methods to obtain a {@code SecureRandom} object, and
734 * then call the {@code generateSeed} method to obtain seed bytes
735 * from that object.
736 *
737 * @param numBytes the number of seed bytes to generate.
738 *
739 * @return the seed bytes.
740 *
741 * @see #setSeed
742 */
743 public static byte[] getSeed(int numBytes) {
744 SecureRandom seedGen = seedGenerator;
745 if (seedGen == null) {
746 seedGen = new SecureRandom();
747 seedGenerator = seedGen;
748 }
749 return seedGen.generateSeed(numBytes);
750 }
751
752 /**
753 * Returns the given number of seed bytes, computed using the seed
754 * generation algorithm that this class uses to seed itself. This
755 * call may be used to seed other random number generators.
756 *
757 * @param numBytes the number of seed bytes to generate.
758 * @throws IllegalArgumentException if {@code numBytes} is negative
759 * @return the seed bytes.
760 */
761 public byte[] generateSeed(int numBytes) {
762 if (numBytes < 0) {
763 throw new IllegalArgumentException("numBytes cannot be negative");
764 }
765 return secureRandomSpi.engineGenerateSeed(numBytes);
766 }
767
768 /**
769 * Helper function to convert a long into a byte array (least significant
770 * byte first).
771 */
772 private static byte[] longToByteArray(long l) {
773 byte[] retVal = new byte[8];
774
775 for (int i = 0; i < 8; i++) {
776 retVal[i] = (byte) l;
777 l >>= 8;
778 }
779
780 return retVal;
781 }
782
783 /**
784 * Gets a default PRNG algorithm by looking through all registered
785 * providers. Returns the first PRNG algorithm of the first provider that
786 * has registered a {@code SecureRandom} implementation, or null if none of
787 * the registered providers supplies a {@code SecureRandom} implementation.
788 */
789 private static String getPrngAlgorithm() {
790 for (Provider p : Providers.getProviderList().providers()) {
791 for (Service s : p.getServices()) {
792 if (s.getType().equals("SecureRandom")) {
793 return s.getAlgorithm();
794 }
795 }
796 }
797 return null;
798 }
799
800 /*
801 * Lazily initialize since Pattern.compile() is heavy.
802 * Effective Java (2nd Edition), Item 71.
803 */
804 private static final class StrongPatternHolder {
805 /*
806 * Entries are alg:prov separated by ,
807 * Allow for prepended/appended whitespace between entries.
808 *
809 * Capture groups:
810 * 1 - alg
811 * 2 - :prov (optional)
812 * 3 - prov (optional)
813 * 4 - ,nextEntry (optional)
814 * 5 - nextEntry (optional)
815 */
816 private static Pattern pattern =
817 Pattern.compile(
818 "\\s*([\\S&&[^:,]]*)(\\:([\\S&&[^,]]*))?\\s*(\\,(.*))?");
819 }
820
821 /**
822 * Returns a {@code SecureRandom} object that was selected by using
823 * the algorithms/providers specified in the {@code
824 * securerandom.strongAlgorithms} {@link Security} property.
825 * <p>
826 * Some situations require strong random values, such as when
827 * creating high-value/long-lived secrets like RSA public/private
828 * keys. To help guide applications in selecting a suitable strong
829 * {@code SecureRandom} implementation, Java distributions
830 * include a list of known strong {@code SecureRandom}
831 * implementations in the {@code securerandom.strongAlgorithms}
832 * Security property.
833 * <p>
834 * Every implementation of the Java platform is required to
835 * support at least one strong {@code SecureRandom} implementation.
836 *
837 * @return a strong {@code SecureRandom} implementation as indicated
838 * by the {@code securerandom.strongAlgorithms} Security property
839 *
840 * @throws NoSuchAlgorithmException if no algorithm is available
841 *
842 * @see Security#getProperty(String)
843 *
844 * @since 1.8
845 */
846 public static SecureRandom getInstanceStrong()
847 throws NoSuchAlgorithmException {
848
849 String property = AccessController.doPrivileged(
850 new PrivilegedAction<>() {
851 @Override
852 public String run() {
853 return Security.getProperty(
854 "securerandom.strongAlgorithms");
855 }
856 });
857
858 if ((property == null) || (property.length() == 0)) {
859 throw new NoSuchAlgorithmException(
860 "Null/empty securerandom.strongAlgorithms Security Property");
861 }
862
863 String remainder = property;
864 while (remainder != null) {
865 Matcher m;
866 if ((m = StrongPatternHolder.pattern.matcher(
867 remainder)).matches()) {
868
869 String alg = m.group(1);
870 String prov = m.group(3);
871
872 try {
873 if (prov == null) {
874 return SecureRandom.getInstance(alg);
875 } else {
876 return SecureRandom.getInstance(alg, prov);
877 }
878 } catch (NoSuchAlgorithmException |
879 NoSuchProviderException e) {
880 }
881 remainder = m.group(5);
882 } else {
883 remainder = null;
884 }
885 }
886
887 throw new NoSuchAlgorithmException(
888 "No strong SecureRandom impls available: " + property);
889 }
890
891 /**
892 * Reseeds this {@code SecureRandom} with entropy input read from its
893 * entropy source.
894 *
895 * @throws UnsupportedOperationException if the underlying provider
896 * implementation has not overridden this method.
897 *
898 * @since 9
899 */
900 public synchronized void reseed() {
901 secureRandomSpi.engineReseed(null);
902 }
903
904 /**
905 * Reseeds this {@code SecureRandom} with entropy input read from its
906 * entropy source with additional parameters.
907 * <p>
908 * Note that entropy is obtained from an entropy source. While
909 * some data in {@code params} may contain entropy, its main usage is to
910 * provide diversity.
911 *
912 * @param params extra parameters
913 * @throws UnsupportedOperationException if the underlying provider
914 * implementation has not overridden this method.
915 * @throws IllegalArgumentException if {@code params} is {@code null},
916 * illegal or unsupported by this {@code SecureRandom}
917 *
918 * @since 9
919 */
920 public synchronized void reseed(SecureRandomParameters params) {
921 if (params == null) {
922 throw new IllegalArgumentException("params cannot be null");
923 }
924 secureRandomSpi.engineReseed(params);
925 }
926
927 // Declare serialVersionUID to be compatible with JDK1.1
928 static final long serialVersionUID = 4940670005562187L;
929
930 // Retain unused values serialized from JDK1.1
931 /**
932 * @serial
933 */
934 private byte[] state;
935 /**
936 * @serial
937 */
938 private MessageDigest digest = null;
939 /**
940 * @serial
941 *
942 * We know that the MessageDigest class does not implement
943 * java.io.Serializable. However, since this field is no longer
944 * used, it will always be NULL and won't affect the serialization
945 * of the {@code SecureRandom} class itself.
946 */
947 private byte[] randomBytes;
948 /**
949 * @serial
950 */
951 private int randomBytesUsed;
952 /**
953 * @serial
954 */
955 private long counter;
956 }