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| 1 | /* | ||
| 2 | * Copyright (c) 1996, 2011, 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 | |||
| 30 | import java.security.Provider.Service; | ||
| 31 | |||
| 32 | import sun.security.jca.*; | ||
| 33 | import sun.security.jca.GetInstance.Instance; | ||
| 34 | |||
| 35 | /** | ||
| 36 | * This class provides a cryptographically strong random number | ||
| 37 | * generator (RNG). | ||
| 38 | * | ||
| 39 | * <p>A cryptographically strong random number | ||
| 40 | * minimally complies with the statistical random number generator tests | ||
| 41 | * specified in <a href="http://csrc.nist.gov/cryptval/140-2.htm"> | ||
| 42 | * <i>FIPS 140-2, Security Requirements for Cryptographic Modules</i></a>, | ||
| 43 | * section 4.9.1. | ||
| 44 | * Additionally, SecureRandom must produce non-deterministic output. | ||
| 45 | * Therefore any seed material passed to a SecureRandom object must be | ||
| 46 | * unpredictable, and all SecureRandom output sequences must be | ||
| 47 | * cryptographically strong, as described in | ||
| 48 | * <a href="http://www.ietf.org/rfc/rfc1750.txt"> | ||
| 49 | * <i>RFC 1750: Randomness Recommendations for Security</i></a>. | ||
| 50 | * | ||
| 51 | * <p>A caller obtains a SecureRandom instance via the | ||
| 52 | * no-argument constructor or one of the <code>getInstance</code> methods: | ||
| 53 | * | ||
| 54 | * <pre> | ||
| 55 | * SecureRandom random = new SecureRandom(); | ||
| 56 | * </pre> | ||
| 57 | * | ||
| 58 | * <p> Many SecureRandom implementations are in the form of a pseudo-random | ||
| 59 | * number generator (PRNG), which means they use a deterministic algorithm | ||
| 60 | * to produce a pseudo-random sequence from a true random seed. | ||
| 61 | * Other implementations may produce true random numbers, | ||
| 62 | * and yet others may use a combination of both techniques. | ||
| 63 | * | ||
| 64 | * <p> Typical callers of SecureRandom invoke the following methods | ||
| 65 | * to retrieve random bytes: | ||
| 66 | * | ||
| 67 | * <pre> | ||
| 68 | * SecureRandom random = new SecureRandom(); | ||
| 69 | * byte bytes[] = new byte[20]; | ||
| 70 | * random.nextBytes(bytes); | ||
| 71 | * </pre> | ||
| 72 | * | ||
| 73 | * <p> Callers may also invoke the <code>generateSeed</code> method | ||
| 74 | * to generate a given number of seed bytes (to seed other random number | ||
| 75 | * generators, for example): | ||
| 76 | * <pre> | ||
| 77 | * byte seed[] = random.generateSeed(20); | ||
| 78 | * </pre> | ||
| 79 | * | ||
| 80 | * Note: Depending on the implementation, the <code>generateSeed</code> and | ||
| 81 | * <code>nextBytes</code> methods may block as entropy is being gathered, | ||
| 82 | * for example, if they need to read from /dev/random on various unix-like | ||
| 83 | * operating systems. | ||
| 84 | * | ||
| 85 | * @see java.security.SecureRandomSpi | ||
| 86 | * @see java.util.Random | ||
| 87 | * | ||
| 88 | * @author Benjamin Renaud | ||
| 89 | * @author Josh Bloch | ||
| 90 | */ | ||
| 91 | |||
| 92 | public class SecureRandom extends java.util.Random { | ||
| 93 | |||
| 94 | /** | ||
| 95 | * The provider. | ||
| 96 | * | ||
| 97 | * @serial | ||
| 98 | * @since 1.2 | ||
| 99 | */ | ||
| 100 | private Provider provider = null; | ||
| 101 | |||
| 102 | /** | ||
| 103 | * The provider implementation. | ||
| 104 | * | ||
| 105 | * @serial | ||
| 106 | * @since 1.2 | ||
| 107 | */ | ||
| 108 | private SecureRandomSpi secureRandomSpi = null; | ||
| 109 | |||
| 110 | /* | ||
| 111 | * The algorithm name of null if unknown. | ||
| 112 | * | ||
| 113 | * @serial | ||
| 114 | * @since 1.5 | ||
| 115 | */ | ||
| 116 | private String algorithm; | ||
| 117 | |||
| 118 | // Seed Generator | ||
| 119 | private static volatile SecureRandom seedGenerator = null; | ||
| 120 | |||
| 121 | /** | ||
| 122 | * Constructs a secure random number generator (RNG) implementing the | ||
| 123 | * default random number algorithm. | ||
| 124 | * | ||
| 125 | * <p> This constructor traverses the list of registered security Providers, | ||
| 126 | * starting with the most preferred Provider. | ||
| 127 | * A new SecureRandom object encapsulating the | ||
| 128 | * SecureRandomSpi implementation from the first | ||
| 129 | * Provider that supports a SecureRandom (RNG) algorithm is returned. | ||
| 130 | * If none of the Providers support a RNG algorithm, | ||
| 131 | * then an implementation-specific default is returned. | ||
| 132 | * | ||
| 133 | * <p> Note that the list of registered providers may be retrieved via | ||
| 134 | * the {@link Security#getProviders() Security.getProviders()} method. | ||
| 135 | * | ||
| 136 | * <p> See the SecureRandom section in the <a href= | ||
| 137 | * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom"> | ||
| 138 | * Java Cryptography Architecture Standard Algorithm Name Documentation</a> | ||
| 139 | * for information about standard RNG algorithm names. | ||
| 140 | * | ||
| 141 | * <p> The returned SecureRandom object has not been seeded. To seed the | ||
| 142 | * returned object, call the <code>setSeed</code> method. | ||
| 143 | * If <code>setSeed</code> is not called, the first call to | ||
| 144 | * <code>nextBytes</code> will force the SecureRandom object to seed itself. | ||
| 145 | * This self-seeding will not occur if <code>setSeed</code> was | ||
| 146 | * previously called. | ||
| 147 | */ | ||
| 148 | public SecureRandom() { | ||
| 149 | /* | ||
| 150 | * This call to our superclass constructor will result in a call | ||
| 151 | * to our own <code>setSeed</code> method, which will return | ||
| 152 | * immediately when it is passed zero. | ||
| 153 | */ | ||
| 154 | super(0); | ||
| 155 | getDefaultPRNG(false, null); | ||
| 156 | } | ||
| 157 | |||
| 158 | /** | ||
| 159 | * Constructs a secure random number generator (RNG) implementing the | ||
| 160 | * default random number algorithm. | ||
| 161 | * The SecureRandom instance is seeded with the specified seed bytes. | ||
| 162 | * | ||
| 163 | * <p> This constructor traverses the list of registered security Providers, | ||
| 164 | * starting with the most preferred Provider. | ||
| 165 | * A new SecureRandom object encapsulating the | ||
| 166 | * SecureRandomSpi implementation from the first | ||
| 167 | * Provider that supports a SecureRandom (RNG) algorithm is returned. | ||
| 168 | * If none of the Providers support a RNG algorithm, | ||
| 169 | * then an implementation-specific default is returned. | ||
| 170 | * | ||
| 171 | * <p> Note that the list of registered providers may be retrieved via | ||
| 172 | * the {@link Security#getProviders() Security.getProviders()} method. | ||
| 173 | * | ||
| 174 | * <p> See the SecureRandom section in the <a href= | ||
| 175 | * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom"> | ||
| 176 | * Java Cryptography Architecture Standard Algorithm Name Documentation</a> | ||
| 177 | * for information about standard RNG algorithm names. | ||
| 178 | * | ||
| 179 | * @param seed the seed. | ||
| 180 | */ | ||
| 181 | public SecureRandom(byte seed[]) { | ||
| 182 | super(0); | ||
| 183 | getDefaultPRNG(true, seed); | ||
| 184 | } | ||
| 185 | |||
| 186 | private void getDefaultPRNG(boolean setSeed, byte[] seed) { | ||
| 187 | String prng = getPrngAlgorithm(); | ||
| 188 | if (prng == null) { | ||
| 189 | // bummer, get the SUN implementation | ||
| 190 | prng = "SHA1PRNG"; | ||
| 191 | this.secureRandomSpi = new sun.security.provider.SecureRandom(); | ||
| 192 | this.provider = Providers.getSunProvider(); | ||
| 193 | if (setSeed) { | ||
| 194 | this.secureRandomSpi.engineSetSeed(seed); | ||
| 195 | } | ||
| 196 | } else { | ||
| 197 | try { | ||
| 198 | SecureRandom random = SecureRandom.getInstance(prng); | ||
| 199 | this.secureRandomSpi = random.getSecureRandomSpi(); | ||
| 200 | this.provider = random.getProvider(); | ||
| 201 | if (setSeed) { | ||
| 202 | this.secureRandomSpi.engineSetSeed(seed); | ||
| 203 | } | ||
| 204 | } catch (NoSuchAlgorithmException nsae) { | ||
| 205 | // never happens, because we made sure the algorithm exists | ||
| 206 | throw new RuntimeException(nsae); | ||
| 207 | } | ||
| 208 | } | ||
| 209 | // JDK 1.1 based implementations subclass SecureRandom instead of | ||
| 210 | // SecureRandomSpi. They will also go through this code path because | ||
| 211 | // they must call a SecureRandom constructor as it is their superclass. | ||
| 212 | // If we are dealing with such an implementation, do not set the | ||
| 213 | // algorithm value as it would be inaccurate. | ||
| 214 | if (getClass() == SecureRandom.class) { | ||
| 215 | this.algorithm = prng; | ||
| 216 | } | ||
| 217 | } | ||
| 218 | |||
| 219 | /** | ||
| 220 | * Creates a SecureRandom object. | ||
| 221 | * | ||
| 222 | * @param secureRandomSpi the SecureRandom implementation. | ||
| 223 | * @param provider the provider. | ||
| 224 | */ | ||
| 225 | protected SecureRandom(SecureRandomSpi secureRandomSpi, | ||
| 226 | Provider provider) { | ||
| 227 | this(secureRandomSpi, provider, null); | ||
| 228 | } | ||
| 229 | |||
| 230 | private SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider, | ||
| 231 | String algorithm) { | ||
| 232 | super(0); | ||
| 233 | this.secureRandomSpi = secureRandomSpi; | ||
| 234 | this.provider = provider; | ||
| 235 | this.algorithm = algorithm; | ||
| 236 | } | ||
| 237 | |||
| 238 | /** | ||
| 239 | * Returns a SecureRandom object that implements the specified | ||
| 240 | * Random Number Generator (RNG) algorithm. | ||
| 241 | * | ||
| 242 | * <p> This method traverses the list of registered security Providers, | ||
| 243 | * starting with the most preferred Provider. | ||
| 244 | * A new SecureRandom object encapsulating the | ||
| 245 | * SecureRandomSpi implementation from the first | ||
| 246 | * Provider that supports the specified algorithm is returned. | ||
| 247 | * | ||
| 248 | * <p> Note that the list of registered providers may be retrieved via | ||
| 249 | * the {@link Security#getProviders() Security.getProviders()} method. | ||
| 250 | * | ||
| 251 | * <p> The returned SecureRandom object has not been seeded. To seed the | ||
| 252 | * returned object, call the <code>setSeed</code> method. | ||
| 253 | * If <code>setSeed</code> is not called, the first call to | ||
| 254 | * <code>nextBytes</code> will force the SecureRandom object to seed itself. | ||
| 255 | * This self-seeding will not occur if <code>setSeed</code> was | ||
| 256 | * previously called. | ||
| 257 | * | ||
| 258 | * @param algorithm the name of the RNG algorithm. | ||
| 259 | * See the SecureRandom section in the <a href= | ||
| 260 | * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom"> | ||
| 261 | * Java Cryptography Architecture Standard Algorithm Name Documentation</a> | ||
| 262 | * for information about standard RNG algorithm names. | ||
| 263 | * | ||
| 264 | * @return the new SecureRandom object. | ||
| 265 | * | ||
| 266 | * @exception NoSuchAlgorithmException if no Provider supports a | ||
| 267 | * SecureRandomSpi implementation for the | ||
| 268 | * specified algorithm. | ||
| 269 | * | ||
| 270 | * @see Provider | ||
| 271 | * | ||
| 272 | * @since 1.2 | ||
| 273 | */ | ||
| 274 | public static SecureRandom getInstance(String algorithm) | ||
| 275 | throws NoSuchAlgorithmException { | ||
| 276 | Instance instance = GetInstance.getInstance("SecureRandom", | ||
| 277 | SecureRandomSpi.class, algorithm); | ||
| 278 | return new SecureRandom((SecureRandomSpi)instance.impl, | ||
| 279 | instance.provider, algorithm); | ||
| 280 | } | ||
| 281 | |||
| 282 | /** | ||
| 283 | * Returns a SecureRandom object that implements the specified | ||
| 284 | * Random Number Generator (RNG) algorithm. | ||
| 285 | * | ||
| 286 | * <p> A new SecureRandom object encapsulating the | ||
| 287 | * SecureRandomSpi implementation from the specified provider | ||
| 288 | * is returned. The specified provider must be registered | ||
| 289 | * in the security provider list. | ||
| 290 | * | ||
| 291 | * <p> Note that the list of registered providers may be retrieved via | ||
| 292 | * the {@link Security#getProviders() Security.getProviders()} method. | ||
| 293 | * | ||
| 294 | * <p> The returned SecureRandom object has not been seeded. To seed the | ||
| 295 | * returned object, call the <code>setSeed</code> method. | ||
| 296 | * If <code>setSeed</code> is not called, the first call to | ||
| 297 | * <code>nextBytes</code> will force the SecureRandom object to seed itself. | ||
| 298 | * This self-seeding will not occur if <code>setSeed</code> was | ||
| 299 | * previously called. | ||
| 300 | * | ||
| 301 | * @param algorithm the name of the RNG algorithm. | ||
| 302 | * See the SecureRandom section in the <a href= | ||
| 303 | * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom"> | ||
| 304 | * Java Cryptography Architecture Standard Algorithm Name Documentation</a> | ||
| 305 | * for information about standard RNG algorithm names. | ||
| 306 | * | ||
| 307 | * @param provider the name of the provider. | ||
| 308 | * | ||
| 309 | * @return the new SecureRandom object. | ||
| 310 | * | ||
| 311 | * @exception NoSuchAlgorithmException if a SecureRandomSpi | ||
| 312 | * implementation for the specified algorithm is not | ||
| 313 | * available from the specified provider. | ||
| 314 | * | ||
| 315 | * @exception NoSuchProviderException if the specified provider is not | ||
| 316 | * registered in the security provider list. | ||
| 317 | * | ||
| 318 | * @exception IllegalArgumentException if the provider name is null | ||
| 319 | * or empty. | ||
| 320 | * | ||
| 321 | * @see Provider | ||
| 322 | * | ||
| 323 | * @since 1.2 | ||
| 324 | */ | ||
| 325 | public static SecureRandom getInstance(String algorithm, String provider) | ||
| 326 | throws NoSuchAlgorithmException, NoSuchProviderException { | ||
| 327 | Instance instance = GetInstance.getInstance("SecureRandom", | ||
| 328 | SecureRandomSpi.class, algorithm, provider); | ||
| 329 | return new SecureRandom((SecureRandomSpi)instance.impl, | ||
| 330 | instance.provider, algorithm); | ||
| 331 | } | ||
| 332 | |||
| 333 | /** | ||
| 334 | * Returns a SecureRandom object that implements the specified | ||
| 335 | * Random Number Generator (RNG) algorithm. | ||
| 336 | * | ||
| 337 | * <p> A new SecureRandom object encapsulating the | ||
| 338 | * SecureRandomSpi implementation from the specified Provider | ||
| 339 | * object is returned. Note that the specified Provider object | ||
| 340 | * does not have to be registered in the provider list. | ||
| 341 | * | ||
| 342 | * <p> The returned SecureRandom object has not been seeded. To seed the | ||
| 343 | * returned object, call the <code>setSeed</code> method. | ||
| 344 | * If <code>setSeed</code> is not called, the first call to | ||
| 345 | * <code>nextBytes</code> will force the SecureRandom object to seed itself. | ||
| 346 | * This self-seeding will not occur if <code>setSeed</code> was | ||
| 347 | * previously called. | ||
| 348 | * | ||
| 349 | * @param algorithm the name of the RNG algorithm. | ||
| 350 | * See the SecureRandom section in the <a href= | ||
| 351 | * "{@docRoot}/../technotes/guides/security/StandardNames.html#SecureRandom"> | ||
| 352 | * Java Cryptography Architecture Standard Algorithm Name Documentation</a> | ||
| 353 | * for information about standard RNG algorithm names. | ||
| 354 | * | ||
| 355 | * @param provider the provider. | ||
| 356 | * | ||
| 357 | * @return the new SecureRandom object. | ||
| 358 | * | ||
| 359 | * @exception NoSuchAlgorithmException if a SecureRandomSpi | ||
| 360 | * implementation for the specified algorithm is not available | ||
| 361 | * from the specified Provider object. | ||
| 362 | * | ||
| 363 | * @exception IllegalArgumentException if the specified provider is null. | ||
| 364 | * | ||
| 365 | * @see Provider | ||
| 366 | * | ||
| 367 | * @since 1.4 | ||
| 368 | */ | ||
| 369 | public static SecureRandom getInstance(String algorithm, | ||
| 370 | Provider provider) throws NoSuchAlgorithmException { | ||
| 371 | Instance instance = GetInstance.getInstance("SecureRandom", | ||
| 372 | SecureRandomSpi.class, algorithm, provider); | ||
| 373 | return new SecureRandom((SecureRandomSpi)instance.impl, | ||
| 374 | instance.provider, algorithm); | ||
| 375 | } | ||
| 376 | |||
| 377 | /** | ||
| 378 | * Returns the SecureRandomSpi of this SecureRandom object. | ||
| 379 | */ | ||
| 380 | SecureRandomSpi getSecureRandomSpi() { | ||
| 381 | return secureRandomSpi; | ||
| 382 | } | ||
| 383 | |||
| 384 | /** | ||
| 385 | * Returns the provider of this SecureRandom object. | ||
| 386 | * | ||
| 387 | * @return the provider of this SecureRandom object. | ||
| 388 | */ | ||
| 389 | public final Provider getProvider() { | ||
| 390 | return provider; | ||
| 391 | } | ||
| 392 | |||
| 393 | /** | ||
| 394 | * Returns the name of the algorithm implemented by this SecureRandom | ||
| 395 | * object. | ||
| 396 | * | ||
| 397 | * @return the name of the algorithm or <code>unknown</code> | ||
| 398 | * if the algorithm name cannot be determined. | ||
| 399 | * @since 1.5 | ||
| 400 | */ | ||
| 401 | public String getAlgorithm() { | ||
| 402 | return (algorithm != null) ? algorithm : "unknown"; | ||
| 403 | } | ||
| 404 | |||
| 405 | /** | ||
| 406 | * Reseeds this random object. The given seed supplements, rather than | ||
| 407 | * replaces, the existing seed. Thus, repeated calls are guaranteed | ||
| 408 | * never to reduce randomness. | ||
| 409 | * | ||
| 410 | * @param seed the seed. | ||
| 411 | * | ||
| 412 | * @see #getSeed | ||
| 413 | */ | ||
| 414 | synchronized public void setSeed(byte[] seed) { | ||
| 415 | secureRandomSpi.engineSetSeed(seed); | ||
| 416 | } | ||
| 417 | |||
| 418 | /** | ||
| 419 | * Reseeds this random object, using the eight bytes contained | ||
| 420 | * in the given <code>long seed</code>. The given seed supplements, | ||
| 421 | * rather than replaces, the existing seed. Thus, repeated calls | ||
| 422 | * are guaranteed never to reduce randomness. | ||
| 423 | * | ||
| 424 | * <p>This method is defined for compatibility with | ||
| 425 | * <code>java.util.Random</code>. | ||
| 426 | * | ||
| 427 | * @param seed the seed. | ||
| 428 | * | ||
| 429 | * @see #getSeed | ||
| 430 | */ | ||
| 431 | public void setSeed(long seed) { | ||
| 432 | /* | ||
| 433 | * Ignore call from super constructor (as well as any other calls | ||
| 434 | * unfortunate enough to be passing 0). It's critical that we | ||
| 435 | * ignore call from superclass constructor, as digest has not | ||
| 436 | * yet been initialized at that point. | ||
| 437 | */ | ||
| 438 | if (seed != 0) { | ||
| 439 | secureRandomSpi.engineSetSeed(longToByteArray(seed)); | ||
| 440 | } | ||
| 441 | } | ||
| 442 | |||
| 443 | /** | ||
| 444 | * Generates a user-specified number of random bytes. | ||
| 445 | * | ||
| 446 | * <p> If a call to <code>setSeed</code> had not occurred previously, | ||
| 447 | * the first call to this method forces this SecureRandom object | ||
| 448 | * to seed itself. This self-seeding will not occur if | ||
| 449 | * <code>setSeed</code> was previously called. | ||
| 450 | * | ||
| 451 | * @param bytes the array to be filled in with random bytes. | ||
| 452 | */ | ||
| 453 | |||
| 454 | synchronized public void nextBytes(byte[] bytes) { | ||
| 455 | secureRandomSpi.engineNextBytes(bytes); | ||
| 456 | } | ||
| 457 | |||
| 458 | /** | ||
| 459 | * Generates an integer containing the user-specified number of | ||
| 460 | * pseudo-random bits (right justified, with leading zeros). This | ||
| 461 | * method overrides a <code>java.util.Random</code> method, and serves | ||
| 462 | * to provide a source of random bits to all of the methods inherited | ||
| 463 | * from that class (for example, <code>nextInt</code>, | ||
| 464 | * <code>nextLong</code>, and <code>nextFloat</code>). | ||
| 465 | * | ||
| 466 | * @param numBits number of pseudo-random bits to be generated, where | ||
| 467 | * 0 <= <code>numBits</code> <= 32. | ||
| 468 | * | ||
| 469 | * @return an <code>int</code> containing the user-specified number | ||
| 470 | * of pseudo-random bits (right justified, with leading zeros). | ||
| 471 | */ | ||
| 472 | final protected int next(int numBits) { | ||
| 473 | int numBytes = (numBits+7)/8; | ||
| 474 | byte b[] = new byte[numBytes]; | ||
| 475 | int next = 0; | ||
| 476 | |||
| 477 | nextBytes(b); | ||
| 478 | for (int i = 0; i < numBytes; i++) | ||
| 479 | next = (next << 8) + (b[i] & 0xFF); | ||
| 480 | |||
| 481 | return next >>> (numBytes*8 - numBits); | ||
| 482 | } | ||
| 483 | |||
| 484 | /** | ||
| 485 | * Returns the given number of seed bytes, computed using the seed | ||
| 486 | * generation algorithm that this class uses to seed itself. This | ||
| 487 | * call may be used to seed other random number generators. | ||
| 488 | * | ||
| 489 | * <p>This method is only included for backwards compatibility. | ||
| 490 | * The caller is encouraged to use one of the alternative | ||
| 491 | * <code>getInstance</code> methods to obtain a SecureRandom object, and | ||
| 492 | * then call the <code>generateSeed</code> method to obtain seed bytes | ||
| 493 | * from that object. | ||
| 494 | * | ||
| 495 | * @param numBytes the number of seed bytes to generate. | ||
| 496 | * | ||
| 497 | * @return the seed bytes. | ||
| 498 | * | ||
| 499 | * @see #setSeed | ||
| 500 | */ | ||
| 501 | public static byte[] getSeed(int numBytes) { | ||
| 502 | if (seedGenerator == null) | ||
| 503 | seedGenerator = new SecureRandom(); | ||
| 504 | return seedGenerator.generateSeed(numBytes); | ||
| 505 | } | ||
| 506 | |||
| 507 | /** | ||
| 508 | * Returns the given number of seed bytes, computed using the seed | ||
| 509 | * generation algorithm that this class uses to seed itself. This | ||
| 510 | * call may be used to seed other random number generators. | ||
| 511 | * | ||
| 512 | * @param numBytes the number of seed bytes to generate. | ||
| 513 | * | ||
| 514 | * @return the seed bytes. | ||
| 515 | */ | ||
| 516 | public byte[] generateSeed(int numBytes) { | ||
| 517 | return secureRandomSpi.engineGenerateSeed(numBytes); | ||
| 518 | } | ||
| 519 | |||
| 520 | /** | ||
| 521 | * Helper function to convert a long into a byte array (least significant | ||
| 522 | * byte first). | ||
| 523 | */ | ||
| 524 | private static byte[] longToByteArray(long l) { | ||
| 525 | byte[] retVal = new byte[8]; | ||
| 526 | |||
| 527 | for (int i = 0; i < 8; i++) { | ||
| 528 | retVal[i] = (byte) l; | ||
| 529 | l >>= 8; | ||
| 530 | } | ||
| 531 | |||
| 532 | return retVal; | ||
| 533 | } | ||
| 534 | |||
| 535 | /** | ||
| 536 | * Gets a default PRNG algorithm by looking through all registered | ||
| 537 | * providers. Returns the first PRNG algorithm of the first provider that | ||
| 538 | * has registered a SecureRandom implementation, or null if none of the | ||
| 539 | * registered providers supplies a SecureRandom implementation. | ||
| 540 | */ | ||
| 541 | private static String getPrngAlgorithm() { | ||
| 542 | for (Provider p : Providers.getProviderList().providers()) { | ||
| 543 | for (Service s : p.getServices()) { | ||
| 544 | if (s.getType().equals("SecureRandom")) { | ||
| 545 | return s.getAlgorithm(); | ||
| 546 | } | ||
| 547 | } | ||
| 548 | } | ||
| 549 | return null; | ||
| 550 | } | ||
| 551 | |||
| 552 | // Declare serialVersionUID to be compatible with JDK1.1 | ||
| 553 | static final long serialVersionUID = 4940670005562187L; | ||
| 554 | |||
| 555 | // Retain unused values serialized from JDK1.1 | ||
| 556 | /** | ||
| 557 | * @serial | ||
| 558 | */ | ||
| 559 | private byte[] state; | ||
| 560 | /** | ||
| 561 | * @serial | ||
| 562 | */ | ||
| 563 | private MessageDigest digest = null; | ||
| 564 | /** | ||
| 565 | * @serial | ||
| 566 | * | ||
| 567 | * We know that the MessageDigest class does not implement | ||
| 568 | * java.io.Serializable. However, since this field is no longer | ||
| 569 | * used, it will always be NULL and won't affect the serialization | ||
| 570 | * of the SecureRandom class itself. | ||
| 571 | */ | ||
| 572 | private byte[] randomBytes; | ||
| 573 | /** | ||
| 574 | * @serial | ||
| 575 | */ | ||
| 576 | private int randomBytesUsed; | ||
| 577 | /** | ||
| 578 | * @serial | ||
| 579 | */ | ||
| 580 | private long counter; | ||
| 581 | } | ||