1 /* 2 * Copyright (c) 1996, 2013, 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 import java.util.function.Function; 33 34 import dalvik.system.VMRuntime; 35 import sun.security.jca.*; 36 import sun.security.jca.GetInstance.Instance; 37 38 /** 39 * This class provides a cryptographically strong random number 40 * generator (RNG). 41 * 42 * <p>A cryptographically strong random number 43 * minimally complies with the statistical random number generator tests 44 * specified in <a href="http://csrc.nist.gov/cryptval/140-2.htm"> 45 * <i>FIPS 140-2, Security Requirements for Cryptographic Modules</i></a>, 46 * section 4.9.1. 47 * Additionally, SecureRandom must produce non-deterministic output. 48 * Therefore any seed material passed to a SecureRandom object must be 49 * unpredictable, and all SecureRandom output sequences must be 50 * cryptographically strong, as described in 51 * <a href="http://www.ietf.org/rfc/rfc1750.txt"> 52 * <i>RFC 1750: Randomness Recommendations for Security</i></a>. 53 * 54 * <p>A caller obtains a SecureRandom instance via the 55 * no-argument constructor or one of the {@code getInstance} methods: 56 * 57 * <pre> 58 * SecureRandom random = new SecureRandom(); 59 * </pre> 60 * 61 * <p> Many SecureRandom implementations are in the form of a pseudo-random 62 * number generator (PRNG), which means they use a deterministic algorithm 63 * to produce a pseudo-random sequence from a true random seed. 64 * Other implementations may produce true random numbers, 65 * and yet others may use a combination of both techniques. 66 * 67 * <p> Typical callers of SecureRandom invoke the following methods 68 * to retrieve random bytes: 69 * 70 * <pre> 71 * SecureRandom random = new SecureRandom(); 72 * byte bytes[] = new byte[20]; 73 * random.nextBytes(bytes); 74 * </pre> 75 * 76 * <p> Callers may also invoke the {@code generateSeed} method 77 * to generate a given number of seed bytes (to seed other random number 78 * generators, for example): 79 * <pre> 80 * byte seed[] = random.generateSeed(20); 81 * </pre> 82 * 83 * Note: Depending on the implementation, the {@code generateSeed} and 84 * {@code nextBytes} methods may block as entropy is being gathered, 85 * for example, if they need to read from /dev/random on various Unix-like 86 * operating systems. 87 * 88 * The SHA1PRNG algorithm from the Crypto provider has been deprecated as it was insecure, and also 89 * incorrectly used by some apps as a key derivation function. See 90 * <a href="http://android-developers.blogspot.com/2016/06/security-crypto-provider-deprecated-in.html"> 91 * Security "Crypto" provider deprecated in Android N</a> for details. 92 * 93 * @see java.security.SecureRandomSpi 94 * @see java.util.Random 95 * 96 * @author Benjamin Renaud 97 * @author Josh Bloch 98 */ 99 100 public class SecureRandom extends java.util.Random { 101 102 // Android-removed: this debugging mechanism is not used in Android. 103 /* 104 private static final Debug pdebug = 105 Debug.getInstance("provider", "Provider"); 106 private static final boolean skipDebug = 107 Debug.isOn("engine=") && !Debug.isOn("securerandom"); 108 */ 109 // END Android-removed 110 111 /** 112 * The provider. 113 * 114 * @serial 115 * @since 1.2 116 */ 117 private Provider provider = null; 118 119 /** 120 * The provider implementation. 121 * 122 * @serial 123 * @since 1.2 124 */ 125 private SecureRandomSpi secureRandomSpi = null; 126 127 /* 128 * The algorithm name of null if unknown. 129 * 130 * @serial 131 * @since 1.5 132 */ 133 private String algorithm; 134 135 // Seed Generator 136 private static volatile SecureRandom seedGenerator = null; 137 138 /** 139 * Constructs a secure random number generator (RNG) implementing the 140 * default random number algorithm. 141 * 142 * <p> This constructor traverses the list of registered security Providers, 143 * starting with the most preferred Provider. 144 * A new SecureRandom object encapsulating the 145 * SecureRandomSpi implementation from the first 146 * Provider that supports a SecureRandom (RNG) algorithm is returned. 147 * If none of the Providers support a RNG algorithm, 148 * then an implementation-specific default is returned. 149 * 150 * <p> Note that the list of registered providers may be retrieved via 151 * the {@link Security#getProviders() Security.getProviders()} method. 152 * 153 * <p> See the SecureRandom section in the <a href= 154 * "{@docRoot}openjdk-redirect.html?v=8&path=/technotes/guides/security/StandardNames.html#SecureRandom"> 155 * Java Cryptography Architecture Standard Algorithm Name Documentation</a> 156 * for information about standard RNG algorithm names. 157 * 158 * <p> The returned SecureRandom object has not been seeded. To seed the 159 * returned object, call the {@code setSeed} method. 160 * If {@code setSeed} is not called, the first call to 161 * {@code nextBytes} will force the SecureRandom object to seed itself. 162 * This self-seeding will not occur if {@code setSeed} was 163 * previously called. 164 */ 165 public SecureRandom() { 166 /* 167 * This call to our superclass constructor will result in a call 168 * to our own {@code setSeed} method, which will return 169 * immediately when it is passed zero. 170 */ 171 super(0); 172 getDefaultPRNG(false, null); 173 } 174 175 /** 176 * Constructs a secure random number generator (RNG) implementing the 177 * default random number algorithm. 178 * The SecureRandom instance is seeded with the specified seed bytes. 179 * 180 * <p> This constructor traverses the list of registered security Providers, 181 * starting with the most preferred Provider. 182 * A new SecureRandom object encapsulating the 183 * SecureRandomSpi implementation from the first 184 * Provider that supports a SecureRandom (RNG) algorithm is returned. 185 * If none of the Providers support a RNG algorithm, 186 * then an implementation-specific default is returned. 187 * 188 * <p> Note that the list of registered providers may be retrieved via 189 * the {@link Security#getProviders() Security.getProviders()} method. 190 * 191 * <p> See the SecureRandom section in the <a href= 192 * "{@docRoot}openjdk-redirect.html?v=8&path=/technotes/guides/security/StandardNames.html#SecureRandom"> 193 * Java Cryptography Architecture Standard Algorithm Name Documentation</a> 194 * for information about standard RNG algorithm names. 195 * 196 * @param seed the seed. 197 */ 198 public SecureRandom(byte seed[]) { 199 super(0); 200 getDefaultPRNG(true, seed); 201 } 202 203 private void getDefaultPRNG(boolean setSeed, byte[] seed) { 204 String prng = getPrngAlgorithm(); 205 if (prng == null) { 206 // Android-changed: This should never happen, we always provide a SecureRandom 207 throw new IllegalStateException("No SecureRandom implementation!"); 208 } else { 209 try { 210 SecureRandom random = SecureRandom.getInstance(prng); 211 this.secureRandomSpi = random.getSecureRandomSpi(); 212 this.provider = random.getProvider(); 213 if (setSeed) { 214 this.secureRandomSpi.engineSetSeed(seed); 215 } 216 } catch (NoSuchAlgorithmException nsae) { 217 // never happens, because we made sure the algorithm exists 218 throw new RuntimeException(nsae); 219 } 220 } 221 // JDK 1.1 based implementations subclass SecureRandom instead of 222 // SecureRandomSpi. They will also go through this code path because 223 // they must call a SecureRandom constructor as it is their superclass. 224 // If we are dealing with such an implementation, do not set the 225 // algorithm value as it would be inaccurate. 226 if (getClass() == SecureRandom.class) { 227 this.algorithm = prng; 228 } 229 } 230 231 /** 232 * Creates a SecureRandom object. 233 * 234 * @param secureRandomSpi the SecureRandom implementation. 235 * @param provider the provider. 236 */ 237 protected SecureRandom(SecureRandomSpi secureRandomSpi, 238 Provider provider) { 239 this(secureRandomSpi, provider, null); 240 } 241 242 private SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider, 243 String algorithm) { 244 super(0); 245 this.secureRandomSpi = secureRandomSpi; 246 this.provider = provider; 247 this.algorithm = algorithm; 248 249 // BEGIN Android-removed: this debugging mechanism is not supported in Android. 250 /* 251 if (!skipDebug && pdebug != null) { 252 pdebug.println("SecureRandom." + algorithm + 253 " algorithm from: " + this.provider.getName()); 254 } 255 */ 256 // END Android-removed 257 } 258 259 /** 260 * Returns a SecureRandom object that implements the specified 261 * Random Number Generator (RNG) algorithm. 262 * 263 * <p> This method traverses the list of registered security Providers, 264 * starting with the most preferred Provider. 265 * A new SecureRandom object encapsulating the 266 * SecureRandomSpi implementation from the first 267 * Provider that supports the specified algorithm is returned. 268 * 269 * <p> Note that the list of registered providers may be retrieved via 270 * the {@link Security#getProviders() Security.getProviders()} method. 271 * 272 * <p> The returned SecureRandom object has not been seeded. To seed the 273 * returned object, call the {@code setSeed} method. 274 * If {@code setSeed} is not called, the first call to 275 * {@code nextBytes} will force the SecureRandom object to seed itself. 276 * This self-seeding will not occur if {@code setSeed} was 277 * previously called. 278 * 279 * @param algorithm the name of the RNG algorithm. 280 * See the SecureRandom section in the <a href= 281 * "{@docRoot}openjdk-redirect.html?v=8&path=/technotes/guides/security/StandardNames.html#SecureRandom"> 282 * Java Cryptography Architecture Standard Algorithm Name Documentation</a> 283 * for information about standard RNG algorithm names. 284 * 285 * @return the new SecureRandom object. 286 * 287 * @exception NoSuchAlgorithmException if no Provider supports a 288 * SecureRandomSpi implementation for the 289 * specified algorithm. 290 * 291 * @see Provider 292 * 293 * @since 1.2 294 */ 295 public static SecureRandom getInstance(String algorithm) 296 throws NoSuchAlgorithmException { 297 Instance instance = GetInstance.getInstance("SecureRandom", 298 SecureRandomSpi.class, algorithm); 299 return new SecureRandom((SecureRandomSpi)instance.impl, 300 instance.provider, algorithm); 301 } 302 303 // BEGIN Android-added: Support for Crypto provider workaround 304 /** 305 * Maximum SDK version for which the workaround for the Crypto provider is in place. 306 * 307 * <p> We provide instances from the Crypto provider (although the provider is not installed) to 308 * apps targeting M or earlier versions of the SDK. 309 * 310 * <p> Default is 23 (M). We have it as a field for testability and it shouldn't be changed. 311 * 312 * @hide 313 */ 314 public static final int DEFAULT_SDK_TARGET_FOR_CRYPTO_PROVIDER_WORKAROUND = 23; 315 316 private static int sdkTargetForCryptoProviderWorkaround = 317 DEFAULT_SDK_TARGET_FOR_CRYPTO_PROVIDER_WORKAROUND; 318 319 /** 320 * Only for testing. 321 * 322 * @hide 323 */ 324 public static void setSdkTargetForCryptoProviderWorkaround(int sdkTargetVersion) { 325 sdkTargetForCryptoProviderWorkaround = sdkTargetVersion; 326 } 327 328 /** 329 * Only for testing. 330 * 331 * @hide 332 */ 333 public static int getSdkTargetForCryptoProviderWorkaround() { 334 return sdkTargetForCryptoProviderWorkaround; 335 } 336 // END Android-added: Support for Crypto provider workaround 337 338 /** 339 * Returns a SecureRandom object that implements the specified 340 * Random Number Generator (RNG) algorithm. 341 * 342 * <p> A new SecureRandom object encapsulating the 343 * SecureRandomSpi implementation from the specified provider 344 * is returned. The specified provider must be registered 345 * in the security provider list. 346 * 347 * <p> Note that the list of registered providers may be retrieved via 348 * the {@link Security#getProviders() Security.getProviders()} method. 349 * 350 * <p> The returned SecureRandom object has not been seeded. To seed the 351 * returned object, call the {@code setSeed} method. 352 * If {@code setSeed} is not called, the first call to 353 * {@code nextBytes} will force the SecureRandom object to seed itself. 354 * This self-seeding will not occur if {@code setSeed} was 355 * previously called. 356 * 357 * @param algorithm the name of the RNG algorithm. 358 * See the SecureRandom section in the <a href= 359 * "{@docRoot}openjdk-redirect.html?v=8&path=/technotes/guides/security/StandardNames.html#SecureRandom"> 360 * Java Cryptography Architecture Standard Algorithm Name Documentation</a> 361 * for information about standard RNG algorithm names. 362 * 363 * @param provider the name of the provider. 364 * 365 * @return the new SecureRandom object. 366 * 367 * @exception NoSuchAlgorithmException if a SecureRandomSpi 368 * implementation for the specified algorithm is not 369 * available from the specified provider. 370 * 371 * @exception NoSuchProviderException if the specified provider is not 372 * registered in the security provider list. 373 * 374 * @exception IllegalArgumentException if the provider name is null 375 * or empty. 376 * 377 * @see Provider 378 * 379 * @since 1.2 380 */ 381 public static SecureRandom getInstance(String algorithm, String provider) 382 throws NoSuchAlgorithmException, NoSuchProviderException { 383 try { 384 Instance instance = GetInstance.getInstance("SecureRandom", 385 SecureRandomSpi.class, algorithm, provider); 386 return new SecureRandom((SecureRandomSpi) instance.impl, 387 instance.provider, algorithm); 388 // BEGIN Android-added: Crypto provider deprecation 389 } catch (NoSuchProviderException nspe) { 390 if ("Crypto".equals(provider)) { 391 System.logE(" ********** PLEASE READ ************ "); 392 System.logE(" * "); 393 System.logE(" * New versions of the Android SDK no longer support the Crypto provider."); 394 System.logE(" * If your app was relying on setSeed() to derive keys from strings, you"); 395 System.logE(" * should switch to using SecretKeySpec to load raw key bytes directly OR"); 396 System.logE(" * use a real key derivation function (KDF). See advice here : "); 397 System.logE(" * http://android-developers.blogspot.com/2016/06/security-crypto-provider-deprecated-in.html "); 398 System.logE(" *********************************** "); 399 if (VMRuntime.getRuntime().getTargetSdkVersion() 400 <= sdkTargetForCryptoProviderWorkaround) { 401 System.logE(" Returning an instance of SecureRandom from the Crypto provider"); 402 System.logE(" as a temporary measure so that the apps targeting earlier SDKs"); 403 System.logE(" keep working. Please do not rely on the presence of the Crypto"); 404 System.logE(" provider in the codebase, as our plan is to delete it"); 405 System.logE(" completely in the future."); 406 return getInstanceFromCryptoProvider(algorithm); 407 } 408 } 409 410 throw nspe; 411 } 412 } 413 414 private static SecureRandom getInstanceFromCryptoProvider(String algorithm) 415 throws NoSuchAlgorithmException { 416 Provider cryptoProvider; 417 try { 418 cryptoProvider = (Provider) SecureRandom.class.getClassLoader() 419 .loadClass( 420 "org.apache.harmony.security.provider.crypto.CryptoProvider") 421 .newInstance(); 422 } catch (Exception e) { 423 throw new RuntimeException(e); 424 } 425 Service service = cryptoProvider.getService("SecureRandom", algorithm); 426 Instance instance = GetInstance.getInstance(service, SecureRandomSpi.class); 427 return new SecureRandom( 428 (SecureRandomSpi) instance.impl, instance.provider, algorithm); 429 } 430 // END Android-added: Crypto provider deprecation 431 432 /** 433 * Returns a SecureRandom object that implements the specified 434 * Random Number Generator (RNG) algorithm. 435 * 436 * <p> A new SecureRandom object encapsulating the 437 * SecureRandomSpi implementation from the specified Provider 438 * object is returned. Note that the specified Provider object 439 * does not have to be registered in the provider list. 440 * 441 * <p> The returned SecureRandom object has not been seeded. To seed the 442 * returned object, call the {@code setSeed} method. 443 * If {@code setSeed} is not called, the first call to 444 * {@code nextBytes} will force the SecureRandom object to seed itself. 445 * This self-seeding will not occur if {@code setSeed} was 446 * previously called. 447 * 448 * @param algorithm the name of the RNG algorithm. 449 * See the SecureRandom section in the <a href= 450 * "{@docRoot}openjdk-redirect.html?v=8&path=/technotes/guides/security/StandardNames.html#SecureRandom"> 451 * Java Cryptography Architecture Standard Algorithm Name Documentation</a> 452 * for information about standard RNG algorithm names. 453 * 454 * @param provider the provider. 455 * 456 * @return the new SecureRandom object. 457 * 458 * @exception NoSuchAlgorithmException if a SecureRandomSpi 459 * implementation for the specified algorithm is not available 460 * from the specified Provider object. 461 * 462 * @exception IllegalArgumentException if the specified provider is null. 463 * 464 * @see Provider 465 * 466 * @since 1.4 467 */ 468 public static SecureRandom getInstance(String algorithm, 469 Provider provider) throws NoSuchAlgorithmException { 470 Instance instance = GetInstance.getInstance("SecureRandom", 471 SecureRandomSpi.class, algorithm, provider); 472 return new SecureRandom((SecureRandomSpi)instance.impl, 473 instance.provider, algorithm); 474 } 475 476 /** 477 * Returns the SecureRandomSpi of this SecureRandom object. 478 */ 479 SecureRandomSpi getSecureRandomSpi() { 480 return secureRandomSpi; 481 } 482 483 /** 484 * Returns the provider of this SecureRandom object. 485 * 486 * @return the provider of this SecureRandom object. 487 */ 488 public final Provider getProvider() { 489 return provider; 490 } 491 492 /** 493 * Returns the name of the algorithm implemented by this SecureRandom 494 * object. 495 * 496 * @return the name of the algorithm or {@code unknown} 497 * if the algorithm name cannot be determined. 498 * @since 1.5 499 */ 500 public String getAlgorithm() { 501 return (algorithm != null) ? algorithm : "unknown"; 502 } 503 504 /** 505 * Reseeds this random object. The given seed supplements, rather than 506 * replaces, the existing seed. Thus, repeated calls are guaranteed 507 * never to reduce randomness. 508 * 509 * @param seed the seed. 510 * 511 * @see #getSeed 512 */ 513 synchronized public void setSeed(byte[] seed) { 514 secureRandomSpi.engineSetSeed(seed); 515 } 516 517 /** 518 * Reseeds this random object, using the eight bytes contained 519 * in the given {@code long seed}. The given seed supplements, 520 * rather than replaces, the existing seed. Thus, repeated calls 521 * are guaranteed never to reduce randomness. 522 * 523 * <p>This method is defined for compatibility with 524 * {@code java.util.Random}. 525 * 526 * @param seed the seed. 527 * 528 * @see #getSeed 529 */ 530 @Override 531 public void setSeed(long seed) { 532 /* 533 * Ignore call from super constructor (as well as any other calls 534 * unfortunate enough to be passing 0). It's critical that we 535 * ignore call from superclass constructor, as digest has not 536 * yet been initialized at that point. 537 */ 538 if (seed != 0) { 539 secureRandomSpi.engineSetSeed(longToByteArray(seed)); 540 } 541 } 542 543 /** 544 * Generates a user-specified number of random bytes. 545 * 546 * <p> If a call to {@code setSeed} had not occurred previously, 547 * the first call to this method forces this SecureRandom object 548 * to seed itself. This self-seeding will not occur if 549 * {@code setSeed} was previously called. 550 * 551 * @param bytes the array to be filled in with random bytes. 552 */ 553 @Override 554 // Android-changed: Added synchronized 555 // This method has been synchronized at least since Cupcake, so it would probably 556 // lead to problems if it was removed. 557 synchronized public void nextBytes(byte[] bytes) { 558 secureRandomSpi.engineNextBytes(bytes); 559 } 560 561 /** 562 * Generates an integer containing the user-specified number of 563 * pseudo-random bits (right justified, with leading zeros). This 564 * method overrides a {@code java.util.Random} method, and serves 565 * to provide a source of random bits to all of the methods inherited 566 * from that class (for example, {@code nextInt}, 567 * {@code nextLong}, and {@code nextFloat}). 568 * 569 * @param numBits number of pseudo-random bits to be generated, where 570 * {@code 0 <= numBits <= 32}. 571 * 572 * @return an {@code int} containing the user-specified number 573 * of pseudo-random bits (right justified, with leading zeros). 574 */ 575 @Override 576 final protected int next(int numBits) { 577 int numBytes = (numBits+7)/8; 578 byte b[] = new byte[numBytes]; 579 int next = 0; 580 581 nextBytes(b); 582 for (int i = 0; i < numBytes; i++) { 583 next = (next << 8) + (b[i] & 0xFF); 584 } 585 586 return next >>> (numBytes*8 - numBits); 587 } 588 589 /** 590 * Returns the given number of seed bytes, computed using the seed 591 * generation algorithm that this class uses to seed itself. This 592 * call may be used to seed other random number generators. 593 * 594 * <p>This method is only included for backwards compatibility. 595 * The caller is encouraged to use one of the alternative 596 * {@code getInstance} methods to obtain a SecureRandom object, and 597 * then call the {@code generateSeed} method to obtain seed bytes 598 * from that object. 599 * 600 * @param numBytes the number of seed bytes to generate. 601 * 602 * @return the seed bytes. 603 * 604 * @see #setSeed 605 */ 606 public static byte[] getSeed(int numBytes) { 607 if (seedGenerator == null) { 608 seedGenerator = new SecureRandom(); 609 } 610 return seedGenerator.generateSeed(numBytes); 611 } 612 613 /** 614 * Returns the given number of seed bytes, computed using the seed 615 * generation algorithm that this class uses to seed itself. This 616 * call may be used to seed other random number generators. 617 * 618 * @param numBytes the number of seed bytes to generate. 619 * 620 * @return the seed bytes. 621 */ 622 public byte[] generateSeed(int numBytes) { 623 return secureRandomSpi.engineGenerateSeed(numBytes); 624 } 625 626 /** 627 * Helper function to convert a long into a byte array (least significant 628 * byte first). 629 */ 630 private static byte[] longToByteArray(long l) { 631 byte[] retVal = new byte[8]; 632 633 for (int i = 0; i < 8; i++) { 634 retVal[i] = (byte) l; 635 l >>= 8; 636 } 637 638 return retVal; 639 } 640 641 /** 642 * Gets a default PRNG algorithm by looking through all registered 643 * providers. Returns the first PRNG algorithm of the first provider that 644 * has registered a SecureRandom implementation, or null if none of the 645 * registered providers supplies a SecureRandom implementation. 646 */ 647 private static String getPrngAlgorithm() { 648 for (Provider p : Providers.getProviderList().providers()) { 649 for (Service s : p.getServices()) { 650 if (s.getType().equals("SecureRandom")) { 651 return s.getAlgorithm(); 652 } 653 } 654 } 655 return null; 656 } 657 658 /* 659 * Lazily initialize since Pattern.compile() is heavy. 660 * Effective Java (2nd Edition), Item 71. 661 */ 662 private static final class StrongPatternHolder { 663 /* 664 * Entries are alg:prov separated by , 665 * Allow for prepended/appended whitespace between entries. 666 * 667 * Capture groups: 668 * 1 - alg 669 * 2 - :prov (optional) 670 * 3 - prov (optional) 671 * 4 - ,nextEntry (optional) 672 * 5 - nextEntry (optional) 673 */ 674 private static Pattern pattern = 675 Pattern.compile( 676 "\\s*([\\S&&[^:,]]*)(\\:([\\S&&[^,]]*))?\\s*(\\,(.*))?"); 677 } 678 679 /** 680 * Returns a {@code SecureRandom} object. 681 * 682 * In Android this is equivalent to get a SHA1PRNG from OpenSSLProvider. 683 * 684 * Some situations require strong random values, such as when 685 * creating high-value/long-lived secrets like RSA public/private 686 * keys. To help guide applications in selecting a suitable strong 687 * {@code SecureRandom} implementation, Java distributions 688 * include a list of known strong {@code SecureRandom} 689 * implementations in the {@code securerandom.strongAlgorithms} 690 * Security property. 691 * <p> 692 * Every implementation of the Java platform is required to 693 * support at least one strong {@code SecureRandom} implementation. 694 * 695 * @return a strong {@code SecureRandom} implementation 696 * 697 * @throws NoSuchAlgorithmException if no algorithm is available 698 * 699 * @see Security#getProperty(String) 700 * 701 * @since 1.8 702 */ 703 public static SecureRandom getInstanceStrong() 704 throws NoSuchAlgorithmException { 705 706 String property = AccessController.doPrivileged( 707 new PrivilegedAction<String>() { 708 @Override 709 public String run() { 710 return Security.getProperty( 711 "securerandom.strongAlgorithms"); 712 } 713 }); 714 715 if ((property == null) || (property.length() == 0)) { 716 throw new NoSuchAlgorithmException( 717 "Null/empty securerandom.strongAlgorithms Security Property"); 718 } 719 720 String remainder = property; 721 while (remainder != null) { 722 Matcher m; 723 if ((m = StrongPatternHolder.pattern.matcher( 724 remainder)).matches()) { 725 726 String alg = m.group(1); 727 String prov = m.group(3); 728 729 try { 730 if (prov == null) { 731 return SecureRandom.getInstance(alg); 732 } else { 733 return SecureRandom.getInstance(alg, prov); 734 } 735 } catch (NoSuchAlgorithmException | 736 NoSuchProviderException e) { 737 } 738 remainder = m.group(5); 739 } else { 740 remainder = null; 741 } 742 } 743 744 throw new NoSuchAlgorithmException( 745 "No strong SecureRandom impls available: " + property); 746 } 747 748 // Declare serialVersionUID to be compatible with JDK1.1 749 static final long serialVersionUID = 4940670005562187L; 750 751 // Retain unused values serialized from JDK1.1 752 /** 753 * @serial 754 */ 755 private byte[] state; 756 /** 757 * @serial 758 */ 759 private MessageDigest digest = null; 760 /** 761 * @serial 762 * 763 * We know that the MessageDigest class does not implement 764 * java.io.Serializable. However, since this field is no longer 765 * used, it will always be NULL and won't affect the serialization 766 * of the SecureRandom class itself. 767 */ 768 private byte[] randomBytes; 769 /** 770 * @serial 771 */ 772 private int randomBytesUsed; 773 /** 774 * @serial 775 */ 776 private long counter; 777 } 778