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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/gnu/java/security/prng/MDGenerator.java | |
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Diffstat (limited to 'libjava/classpath/gnu/java/security/prng/MDGenerator.java')
-rw-r--r-- | libjava/classpath/gnu/java/security/prng/MDGenerator.java | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/java/security/prng/MDGenerator.java b/libjava/classpath/gnu/java/security/prng/MDGenerator.java new file mode 100644 index 000000000..b110486f4 --- /dev/null +++ b/libjava/classpath/gnu/java/security/prng/MDGenerator.java @@ -0,0 +1,127 @@ +/* MDGenerator.java -- + Copyright (C) 2001, 2002, 2006 Free Software Foundation, Inc. + +This file is a 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 of the License, 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; if not, write to the Free Software +Foundation, Inc., 51 Franklin St, 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.prng; + +import gnu.java.security.Registry; +import gnu.java.security.hash.HashFactory; +import gnu.java.security.hash.IMessageDigest; + +import java.util.Map; + +/** + * A simple pseudo-random number generator that relies on a hash algorithm, that + * (a) starts its operation by hashing a <code>seed</code>, and then (b) + * continuously re-hashing its output. If no hash algorithm name is specified in + * the {@link Map} of attributes used to initialise the instance then the + * SHA-160 algorithm is used as the underlying hash function. Also, if no + * <code>seed</code> is given, an empty octet sequence is used. + */ +public class MDGenerator + extends BasePRNG + implements Cloneable +{ + /** Property name of underlying hash algorithm for this generator. */ + public static final String MD_NAME = "gnu.crypto.prng.md.hash.name"; + + /** Property name of seed material. */ + public static final String SEEED = "gnu.crypto.prng.md.seed"; + + /** The underlying hash instance. */ + private IMessageDigest md; + + /** Trivial 0-arguments constructor. */ + public MDGenerator() + { + super(Registry.MD_PRNG); + } + + public void setup(Map attributes) + { + // find out which hash to use + String underlyingMD = (String) attributes.get(MD_NAME); + if (underlyingMD == null) + { + if (md == null) + { // happy birthday + // ensure we have a reliable implementation of this hash + md = HashFactory.getInstance(Registry.SHA160_HASH); + } + else // a clone. reset it for reuse + md.reset(); + } + else // ensure we have a reliable implementation of this hash + md = HashFactory.getInstance(underlyingMD); + // get the seeed + byte[] seed = (byte[]) attributes.get(SEEED); + if (seed == null) + seed = new byte[0]; + + md.update(seed, 0, seed.length); + } + + public void fillBlock() throws LimitReachedException + { + IMessageDigest mdc = (IMessageDigest) md.clone(); + buffer = mdc.digest(); + md.update(buffer, 0, buffer.length); + } + + public void addRandomByte(final byte b) + { + if (md == null) + throw new IllegalStateException("not initialized"); + md.update(b); + } + + public void addRandomBytes(final byte[] buf, final int off, final int len) + { + if (md == null) + throw new IllegalStateException("not initialized"); + md.update(buf, off, len); + } + + public Object clone() throws CloneNotSupportedException + { + MDGenerator result = (MDGenerator) super.clone(); + if (this.md != null) + result.md = (IMessageDigest) this.md.clone(); + + return result; + } +} |