diff options
author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
---|---|---|
committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/gnu/java/security/util/PRNG.java | |
download | cbb-gcc-4.6.4-554fd8c5195424bdbcabf5de30fdc183aba391bd.tar.bz2 cbb-gcc-4.6.4-554fd8c5195424bdbcabf5de30fdc183aba391bd.tar.xz |
obtained gcc-4.6.4.tar.bz2 from upstream website;upstream
verified gcc-4.6.4.tar.bz2.sig;
imported gcc-4.6.4 source tree from verified upstream tarball.
downloading a git-generated archive based on the 'upstream' tag
should provide you with a source tree that is binary identical
to the one extracted from the above tarball.
if you have obtained the source via the command 'git clone',
however, do note that line-endings of files in your working
directory might differ from line-endings of the respective
files in the upstream repository.
Diffstat (limited to 'libjava/classpath/gnu/java/security/util/PRNG.java')
-rw-r--r-- | libjava/classpath/gnu/java/security/util/PRNG.java | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/security/util/PRNG.java b/libjava/classpath/gnu/java/security/util/PRNG.java new file mode 100644 index 000000000..1bed04dcd --- /dev/null +++ b/libjava/classpath/gnu/java/security/util/PRNG.java @@ -0,0 +1,141 @@ +/* PRNG.java -- A Utility methods for default source of randomness + Copyright (C) 2006 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package gnu.java.security.util; + +import java.util.HashMap; + +import gnu.java.security.prng.IRandom; +import gnu.java.security.prng.LimitReachedException; +import gnu.java.security.prng.MDGenerator; + +/** + * A useful hash-based (SHA) pseudo-random number generator used throughout this + * library. + * + * @see MDGenerator + */ +public class PRNG +{ + /** The underlying {@link IRandom}. */ + private IRandom delegate; + + /** + * Private constructor to enforce using the Factory method. + * + * @param delegate the undelying {@link IRandom} object used. + */ + private PRNG(IRandom delegate) + { + super(); + + this.delegate = delegate; + } + + public static final PRNG getInstance() + { + IRandom delegate = new MDGenerator(); + try + { + HashMap map = new HashMap(); + // initialise it with a seed + long t = System.currentTimeMillis(); + byte[] seed = new byte[] { + (byte)(t >>> 56), (byte)(t >>> 48), + (byte)(t >>> 40), (byte)(t >>> 32), + (byte)(t >>> 24), (byte)(t >>> 16), + (byte)(t >>> 8), (byte) t }; + map.put(MDGenerator.SEEED, seed); + delegate.init(map); // default is to use SHA-1 hash + } + catch (Exception x) + { + throw new ExceptionInInitializerError(x); + } + return new PRNG(delegate); + } + + /** + * Completely fills the designated <code>buffer</code> with random data + * generated by the underlying delegate. + * + * @param buffer the place holder of random bytes generated by the underlying + * delegate. On output, the contents of <code>buffer</code> are + * replaced with pseudo-random data, iff the <code>buffer</code> + * size is not zero. + */ + public void nextBytes(byte[] buffer) + { + nextBytes(buffer, 0, buffer.length); + } + + /** + * Fills the designated <code>buffer</code>, starting from byte at position + * <code>offset</code> with, at most, <code>length</code> bytes of random + * data generated by the underlying delegate. + * + * @see IRandom#nextBytes + */ + public void nextBytes(byte[] buffer, int offset, int length) + { + try + { + delegate.nextBytes(buffer, offset, length); + } + catch (LimitReachedException x) // re-initialise with a seed + { + try + { + HashMap map = new HashMap(); + long t = System.currentTimeMillis(); + byte[] seed = new byte[] { + (byte)(t >>> 56), (byte)(t >>> 48), + (byte)(t >>> 40), (byte)(t >>> 32), + (byte)(t >>> 24), (byte)(t >>> 16), + (byte)(t >>> 8), (byte) t }; + map.put(MDGenerator.SEEED, seed); + delegate.init(map); // default is to use SHA-1 hash + delegate.nextBytes(buffer, offset, length); + } + catch (Exception y) + { + throw new ExceptionInInitializerError(y); + } + } + } +} |