001/* SecureRandom.java --- Secure Random class implementation 002 Copyright (C) 1999, 2001, 2002, 2003, 2005, 2006 003 Free Software Foundation, Inc. 004 005This file is part of GNU Classpath. 006 007GNU Classpath is free software; you can redistribute it and/or modify 008it under the terms of the GNU General Public License as published by 009the Free Software Foundation; either version 2, or (at your option) 010any later version. 011 012GNU Classpath is distributed in the hope that it will be useful, but 013WITHOUT ANY WARRANTY; without even the implied warranty of 014MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 015General Public License for more details. 016 017You should have received a copy of the GNU General Public License 018along with GNU Classpath; see the file COPYING. If not, write to the 019Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02002110-1301 USA. 021 022Linking this library statically or dynamically with other modules is 023making a combined work based on this library. Thus, the terms and 024conditions of the GNU General Public License cover the whole 025combination. 026 027As a special exception, the copyright holders of this library give you 028permission to link this library with independent modules to produce an 029executable, regardless of the license terms of these independent 030modules, and to copy and distribute the resulting executable under 031terms of your choice, provided that you also meet, for each linked 032independent module, the terms and conditions of the license of that 033module. An independent module is a module which is not derived from 034or based on this library. If you modify this library, you may extend 035this exception to your version of the library, but you are not 036obligated to do so. If you do not wish to do so, delete this 037exception statement from your version. */ 038 039package java.security; 040 041import gnu.classpath.SystemProperties; 042import gnu.java.lang.CPStringBuilder; 043import gnu.java.security.Engine; 044import gnu.java.security.action.GetSecurityPropertyAction; 045import gnu.java.security.jce.prng.SecureRandomAdapter; 046import gnu.java.security.jce.prng.Sha160RandomSpi; 047 048import java.io.IOException; 049import java.io.InputStream; 050import java.lang.reflect.InvocationTargetException; 051import java.net.MalformedURLException; 052import java.net.URL; 053import java.util.Enumeration; 054import java.util.Random; 055import java.util.logging.Level; 056import java.util.logging.Logger; 057 058/** 059 * An interface to a cryptographically secure pseudo-random number 060 * generator (PRNG). Random (or at least unguessable) numbers are used 061 * in all areas of security and cryptography, from the generation of 062 * keys and initialization vectors to the generation of random padding 063 * bytes. 064 * 065 * @author Mark Benvenuto (ivymccough@worldnet.att.net) 066 * @author Casey Marshall 067 */ 068public class SecureRandom extends Random 069{ 070 071 // Constants and fields. 072 // ------------------------------------------------------------------------ 073 074 /** Service name for PRNGs. */ 075 private static final String SECURE_RANDOM = "SecureRandom"; 076 077 private static final long serialVersionUID = 4940670005562187L; 078 079 //Serialized Field 080 long counter = 0; //Serialized 081 Provider provider = null; 082 byte[] randomBytes = null; //Always null 083 int randomBytesUsed = 0; 084 SecureRandomSpi secureRandomSpi = null; 085 byte[] state = null; 086 private String algorithm; 087 088 private boolean isSeeded = false; 089 090 // Constructors. 091 // ------------------------------------------------------------------------ 092 093 /** 094 Default constructor for SecureRandom. It constructs a 095 new SecureRandom by instantating the first SecureRandom 096 algorithm in the default security provier. 097 098 It is not seeded and should be seeded using setSeed or else 099 on the first call to getnextBytes it will force a seed. 100 101 It is maintained for backwards compatibility and programs 102 should use {@link #getInstance(java.lang.String)}. 103 */ 104 public SecureRandom() 105 { 106 Provider[] p = Security.getProviders(); 107 108 //Format of Key: SecureRandom.algname 109 String key; 110 111 String classname = null; 112 int i; 113 Enumeration e; 114 for (i = 0; i < p.length; i++) 115 { 116 e = p[i].propertyNames(); 117 while (e.hasMoreElements()) 118 { 119 key = (String) e.nextElement(); 120 if (key.startsWith("SECURERANDOM.")) 121 { 122 if ((classname = p[i].getProperty(key)) != null) 123 { 124 try 125 { 126 secureRandomSpi = (SecureRandomSpi) Class. 127 forName(classname).newInstance(); 128 provider = p[i]; 129 algorithm = key.substring(13); // Minus SecureRandom. 130 return; 131 } 132 catch (ThreadDeath death) 133 { 134 throw death; 135 } 136 catch (Throwable t) 137 { 138 // Ignore. 139 } 140 } 141 } 142 } 143 } 144 145 // Nothing found. Fall back to SHA1PRNG 146 secureRandomSpi = new Sha160RandomSpi(); 147 algorithm = "Sha160"; 148 } 149 150 /** 151 A constructor for SecureRandom. It constructs a new 152 SecureRandom by instantating the first SecureRandom algorithm 153 in the default security provier. 154 155 It is seeded with the passed function and is useful if the user 156 has access to hardware random device (like a radiation detector). 157 158 It is maintained for backwards compatibility and programs 159 should use getInstance. 160 161 @param seed Seed bytes for class 162 */ 163 public SecureRandom(byte[] seed) 164 { 165 this(); 166 setSeed(seed); 167 } 168 169 /** 170 A constructor for SecureRandom. It constructs a new 171 SecureRandom using the specified SecureRandomSpi from 172 the specified security provier. 173 174 @param secureRandomSpi A SecureRandomSpi class 175 @param provider A Provider class 176 */ 177 protected SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider) 178 { 179 this(secureRandomSpi, provider, "unknown"); 180 } 181 182 /** 183 * Private constructor called from the getInstance() method. 184 */ 185 private SecureRandom(SecureRandomSpi secureRandomSpi, Provider provider, 186 String algorithm) 187 { 188 this.secureRandomSpi = secureRandomSpi; 189 this.provider = provider; 190 this.algorithm = algorithm; 191 } 192 193 /** 194 * Returns an instance of a <code>SecureRandom</code> from the first provider 195 * that implements it. 196 * 197 * @param algorithm The algorithm name. 198 * @return A new <code>SecureRandom</code> implementing the given algorithm. 199 * @throws NoSuchAlgorithmException If no installed provider implements the 200 * given algorithm. 201 * @throws IllegalArgumentException if <code>algorithm</code> is 202 * <code>null</code> or is an empty string. 203 */ 204 public static SecureRandom getInstance(String algorithm) 205 throws NoSuchAlgorithmException 206 { 207 Provider[] p = Security.getProviders(); 208 NoSuchAlgorithmException lastException = null; 209 for (int i = 0; i < p.length; i++) 210 try 211 { 212 return getInstance(algorithm, p[i]); 213 } 214 catch (NoSuchAlgorithmException x) 215 { 216 lastException = x; 217 } 218 if (lastException != null) 219 throw lastException; 220 throw new NoSuchAlgorithmException(algorithm); 221 } 222 223 /** 224 * Returns an instance of a <code>SecureRandom</code> for the specified 225 * algorithm from the named provider. 226 * 227 * @param algorithm The algorithm name. 228 * @param provider The provider name. 229 * @return A new <code>SecureRandom</code> implementing the chosen 230 * algorithm. 231 * @throws NoSuchAlgorithmException If the named provider does not implement 232 * the algorithm, or if the implementation cannot be instantiated. 233 * @throws NoSuchProviderException If no provider named <code>provider</code> 234 * is currently installed. 235 * @throws IllegalArgumentException if either <code>algorithm</code> or 236 * <code>provider</code> is <code>null</code> or empty. 237 */ 238 public static SecureRandom getInstance(String algorithm, String provider) 239 throws NoSuchAlgorithmException, NoSuchProviderException 240 { 241 if (provider == null) 242 throw new IllegalArgumentException("provider MUST NOT be null"); 243 provider = provider.trim(); 244 if (provider.length() == 0) 245 throw new IllegalArgumentException("provider MUST NOT be empty"); 246 Provider p = Security.getProvider(provider); 247 if (p == null) 248 throw new NoSuchProviderException(provider); 249 return getInstance(algorithm, p); 250 } 251 252 /** 253 * Returns an instance of a <code>SecureRandom</code> for the specified 254 * algorithm from the given provider. 255 * 256 * @param algorithm The <code>SecureRandom</code> algorithm to create. 257 * @param provider The provider to use. 258 * @throws NoSuchAlgorithmException If the algorithm cannot be found, or if 259 * the class cannot be instantiated. 260 * @throws IllegalArgumentException if either <code>algorithm</code> or 261 * <code>provider</code> is <code>null</code>, or if 262 * <code>algorithm</code> is an empty string. 263 */ 264 public static SecureRandom getInstance(String algorithm, Provider provider) 265 throws NoSuchAlgorithmException 266 { 267 CPStringBuilder sb = new CPStringBuilder("SecureRandom for algorithm [") 268 .append(algorithm).append("] from provider[") 269 .append(provider).append("] could not be created"); 270 Throwable cause; 271 try 272 { 273 Object spi = Engine.getInstance(SECURE_RANDOM, algorithm, provider); 274 return new SecureRandom((SecureRandomSpi) spi, provider, algorithm); 275 } 276 catch (InvocationTargetException x) 277 { 278 cause = x.getCause(); 279 if (cause instanceof NoSuchAlgorithmException) 280 throw (NoSuchAlgorithmException) cause; 281 if (cause == null) 282 cause = x; 283 } 284 catch (ClassCastException x) 285 { 286 cause = x; 287 } 288 NoSuchAlgorithmException x = new NoSuchAlgorithmException(sb.toString()); 289 x.initCause(cause); 290 throw x; 291 } 292 293 /** 294 Returns the provider being used by the current SecureRandom class. 295 296 @return The provider from which this SecureRandom was attained 297 */ 298 public final Provider getProvider() 299 { 300 return provider; 301 } 302 303 /** 304 * Returns the algorithm name used or "unknown" when the algorithm 305 * used couldn't be determined (as when constructed by the protected 306 * 2 argument constructor). 307 * 308 * @since 1.5 309 */ 310 public String getAlgorithm() 311 { 312 return algorithm; 313 } 314 315 /** 316 Seeds the SecureRandom. The class is re-seeded for each call and 317 each seed builds on the previous seed so as not to weaken security. 318 319 @param seed seed bytes to seed with 320 */ 321 public void setSeed(byte[] seed) 322 { 323 secureRandomSpi.engineSetSeed(seed); 324 isSeeded = true; 325 } 326 327 /** 328 Seeds the SecureRandom. The class is re-seeded for each call and 329 each seed builds on the previous seed so as not to weaken security. 330 331 @param seed 8 seed bytes to seed with 332 */ 333 public void setSeed(long seed) 334 { 335 // This particular setSeed will be called by Random.Random(), via 336 // our own constructor, before secureRandomSpi is initialized. In 337 // this case we can't call a method on secureRandomSpi, and we 338 // definitely don't want to throw a NullPointerException. 339 // Therefore we test. 340 if (secureRandomSpi != null) 341 { 342 byte[] tmp = { (byte) (0xff & (seed >> 56)), 343 (byte) (0xff & (seed >> 48)), 344 (byte) (0xff & (seed >> 40)), 345 (byte) (0xff & (seed >> 32)), 346 (byte) (0xff & (seed >> 24)), 347 (byte) (0xff & (seed >> 16)), 348 (byte) (0xff & (seed >> 8)), 349 (byte) (0xff & seed) 350 }; 351 secureRandomSpi.engineSetSeed(tmp); 352 isSeeded = true; 353 } 354 } 355 356 /** 357 Generates a user specified number of bytes. This function 358 is the basis for all the random functions. 359 360 @param bytes array to store generated bytes in 361 */ 362 public void nextBytes(byte[] bytes) 363 { 364 if (!isSeeded) 365 setSeed(getSeed(32)); 366 randomBytesUsed += bytes.length; 367 counter++; 368 secureRandomSpi.engineNextBytes(bytes); 369 } 370 371 /** 372 Generates an integer containing the user specified 373 number of random bits. It is right justified and padded 374 with zeros. 375 376 @param numBits number of random bits to get, 0 <= numBits <= 32; 377 378 @return the random bits 379 */ 380 protected final int next(int numBits) 381 { 382 if (numBits == 0) 383 return 0; 384 385 byte[] tmp = new byte[(numBits + 7) / 8]; 386 this.nextBytes(tmp); 387 int ret = 0; 388 for (int i = 0; i < tmp.length; i++) 389 ret |= (tmp[i] & 0xFF) << (8 * i); 390 391 long mask = (1L << numBits) - 1; 392 return (int) (ret & mask); 393 } 394 395 /** 396 Returns the given number of seed bytes. This method is 397 maintained only for backwards capability. 398 399 @param numBytes number of seed bytes to get 400 401 @return an array containing the seed bytes 402 */ 403 public static byte[] getSeed(int numBytes) 404 { 405 return SecureRandomAdapter.getSeed(numBytes); 406 } 407 408 /** 409 Returns the specified number of seed bytes. 410 411 @param numBytes number of seed bytes to get 412 413 @return an array containing the seed bytes 414 */ 415 public byte[] generateSeed(int numBytes) 416 { 417 return secureRandomSpi.engineGenerateSeed(numBytes); 418 } 419 420}