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    1   /*
    2    * Copyright (c) 1998, 2005, 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   /**
   29    * This class defines the <i>Service Provider Interface</i> (<b>SPI</b>)
   30    * for the <code>SecureRandom</code> class.
   31    * All the abstract methods in this class must be implemented by each
   32    * service provider who wishes to supply the implementation
   33    * of a cryptographically strong pseudo-random number generator.
   34    *
   35    *
   36    * @see SecureRandom
   37    * @since 1.2
   38    */
   39   
   40   public abstract class SecureRandomSpi implements java.io.Serializable {
   41   
   42       private static final long serialVersionUID = -2991854161009191830L;
   43   
   44       /**
   45        * Reseeds this random object. The given seed supplements, rather than
   46        * replaces, the existing seed. Thus, repeated calls are guaranteed
   47        * never to reduce randomness.
   48        *
   49        * @param seed the seed.
   50        */
   51       protected abstract void engineSetSeed(byte[] seed);
   52   
   53       /**
   54        * Generates a user-specified number of random bytes.
   55        *
   56        * <p> If a call to <code>engineSetSeed</code> had not occurred previously,
   57        * the first call to this method forces this SecureRandom implementation
   58        * to seed itself.  This self-seeding will not occur if
   59        * <code>engineSetSeed</code> was previously called.
   60        *
   61        * @param bytes the array to be filled in with random bytes.
   62        */
   63       protected abstract void engineNextBytes(byte[] bytes);
   64   
   65       /**
   66        * Returns the given number of seed bytes.  This call may be used to
   67        * seed other random number generators.
   68        *
   69        * @param numBytes the number of seed bytes to generate.
   70        *
   71        * @return the seed bytes.
   72        */
   73        protected abstract byte[] engineGenerateSeed(int numBytes);
   74   }

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