gnu.java.security.prng

Class BasePRNG

Implemented Interfaces:
Cloneable, IRandom
Known Direct Subclasses:
ARCFour, CSPRNG, Fortuna, Fortuna.Generator, ICMGenerator, MDGenerator, PBKDF2, UMacGenerator

public abstract class BasePRNG
extends Object
implements IRandom

An abstract class to facilitate implementing PRNG algorithms.

Field Summary

protected byte[]
buffer
A temporary buffer to serve random bytes.
protected boolean
initialised
Indicate if this instance has already been initialised or not.
protected String
name
The canonical name prefix of the PRNG algorithm.
protected int
ndx
The index into buffer of where the next byte will come from.

Constructor Summary

BasePRNG(String name)
Trivial constructor for use by concrete subclasses.

Method Summary

void
addRandomByte(byte b)
void
addRandomBytes(byte[] buffer)
void
addRandomBytes(byte[] buffer, int offset, int length)
Object
clone()
This method may be called to create a new copy of the Object.
abstract void
fillBlock()
void
init(Map<K,V> attributes)
boolean
isInitialised()
String
name()
byte
nextByte()
void
nextBytes(byte[] out)
void
nextBytes(byte[] out, int offset, int length)
abstract void
setup(Map<K,V> attributes)

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

buffer

protected byte[] buffer
A temporary buffer to serve random bytes.

initialised

protected boolean initialised
Indicate if this instance has already been initialised or not.

name

protected String name
The canonical name prefix of the PRNG algorithm.

ndx

protected int ndx
The index into buffer of where the next byte will come from.

Constructor Details

BasePRNG

protected BasePRNG(String name)
Trivial constructor for use by concrete subclasses.
Parameters:
name - the canonical name of this instance.

Method Details

addRandomByte

public void addRandomByte(byte b)
Specified by:
addRandomByte in interface IRandom

addRandomBytes

public void addRandomBytes(byte[] buffer)
Specified by:
addRandomBytes in interface IRandom

addRandomBytes

public void addRandomBytes(byte[] buffer,
                           int offset,
                           int length)
Specified by:
addRandomBytes in interface IRandom

clone

public Object clone()
            throws CloneNotSupportedException
This method may be called to create a new copy of the Object. The typical behavior is as follows:
  • o == o.clone() is false
  • o.getClass() == o.clone().getClass() is true
  • o.equals(o) is true

However, these are not strict requirements, and may be violated if necessary. Of the three requirements, the last is the most commonly violated, particularly if the subclass does not override Object.equals(Object).

If the Object you call clone() on does not implement Cloneable (which is a placeholder interface), then a CloneNotSupportedException is thrown. Notice that Object does not implement Cloneable; this method exists as a convenience for subclasses that do.

Object's implementation of clone allocates space for the new Object using the correct class, without calling any constructors, and then fills in all of the new field values with the old field values. Thus, it is a shallow copy. However, subclasses are permitted to make a deep copy.

All array types implement Cloneable, and override this method as follows (it should never fail):

 public Object clone()
 {
   try
     {
       super.clone();
     }
   catch (CloneNotSupportedException e)
     {
       throw new InternalError(e.getMessage());
     }
 }
 
Specified by:
clone in interface IRandom
Overrides:
clone in interface Object
Returns:
a copy of the Object
Throws:
CloneNotSupportedException - If this Object does not implement Cloneable
See Also:
Cloneable

fillBlock

public abstract void fillBlock()
            throws LimitReachedException

init

public void init(Map<K,V> attributes)
Specified by:
init in interface IRandom

isInitialised

public boolean isInitialised()

name

public String name()
Specified by:
name in interface IRandom

nextByte

public byte nextByte()
            throws IllegalStateException,
                   LimitReachedException
Specified by:
nextByte in interface IRandom

nextBytes

public void nextBytes(byte[] out)
            throws IllegalStateException,
                   LimitReachedException

nextBytes

public void nextBytes(byte[] out,
                      int offset,
                      int length)
            throws IllegalStateException,
                   LimitReachedException
Specified by:
nextBytes in interface IRandom

setup

public abstract void setup(Map<K,V> attributes)

BasePRNG.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.