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2003-02-10 Raif S. Naffah <raif@fl.net.au> * gnu/java/security/provider/SHA1PRNG.java (ensureIsSeeded): new method used to ensure seeding has occurred and that a specific seed can be set and used. From-SVN: r62660
127 lines
3.6 KiB
Java
127 lines
3.6 KiB
Java
/* SHA1PRNG.java --- Secure Random SPI SHA1PRNG
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Copyright (C) 1999, 2001, 2003 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.java.security.provider;
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import java.util.Random;
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import java.security.SecureRandomSpi;
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import java.security.MessageDigest;
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import java.security.NoSuchAlgorithmException;
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import java.io.Serializable;
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public class SHA1PRNG extends SecureRandomSpi implements Serializable
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{
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MessageDigest digest;
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byte seed[];
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byte data[];
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int seedpos;
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int datapos;
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private boolean seeded = false; // set to true when we seed this
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public SHA1PRNG()
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{
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try {
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digest = MessageDigest.getInstance("SHA");
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} catch ( NoSuchAlgorithmException nsae) {
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// System.out.println("Failed to find SHA Message Digest: " + nsae);
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// nsae.printStackTrace();
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throw new InternalError ("no SHA implementation found");
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}
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seed = new byte[20];
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seedpos = 0;
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data = new byte[40];
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datapos = 20; // try to force hashing a first block
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}
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public void engineSetSeed(byte[] seed)
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{
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for(int i = 0; i < seed.length; i++)
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this.seed[seedpos++ % 20] ^= seed[i];
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seedpos %= 20;
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}
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public void engineNextBytes(byte[] bytes)
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{
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ensureIsSeeded ();
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int loc = 0;
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while (loc < bytes.length)
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{
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int copy = Math.min (bytes.length - loc, 20 - datapos);
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if (copy > 0)
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{
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System.arraycopy (data, datapos, bytes, loc, copy);
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datapos += copy;
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loc += copy;
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}
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else
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{
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// No data ready for copying, so refill our buffer.
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System.arraycopy( seed, 0, data, 20, 20);
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byte[] digestdata = digest.digest( data );
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System.arraycopy( digestdata, 0, data, 0, 20);
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datapos = 0;
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}
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}
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}
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public byte[] engineGenerateSeed(int numBytes)
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{
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byte tmp[] = new byte[numBytes];
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engineNextBytes( tmp );
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return tmp;
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}
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private void ensureIsSeeded()
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{
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if (!seeded)
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{
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new Random(0L).nextBytes(seed);
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byte[] digestdata = digest.digest(data);
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System.arraycopy(digestdata, 0, data, 0, 20);
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seeded = true;
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}
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}
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}
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