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gnu.java.security.prng
Class BasePRNG  view BasePRNG download BasePRNG.java

java.lang.Object
  extended bygnu.java.security.prng.BasePRNG
All Implemented Interfaces:
java.lang.Cloneable, IRandom
Direct Known Subclasses:
MDGenerator

public abstract class BasePRNG
extends java.lang.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  java.lang.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
protected BasePRNG(java.lang.String name)
          Trivial constructor for use by concrete subclasses.
 
Method Summary
 void addRandomByte(byte b)
          Supplement, or possibly replace, the random state of this PRNG with a random byte.
 void addRandomBytes(byte[] buffer)
          Supplement, or possibly replace, the random state of this PRNG with a sequence of new random bytes.
 void addRandomBytes(byte[] buffer, int offset, int length)
          Supplement, or possibly replace, the random state of this PRNG with a sequence of new random bytes.
 java.lang.Object clone()
          Returns a clone copy of this instance.
abstract  void fillBlock()
           
 void init(java.util.Map attributes)
          Initialises the pseudo-random number generator scheme with the appropriate attributes.
 boolean isInitialised()
           
 java.lang.String name()
          Returns the canonical name of this instance.
 byte nextByte()
          Returns the next 8 bits of random data generated from this instance.
private  byte nextByteInternal()
           
 void nextBytes(byte[] out)
           
 void nextBytes(byte[] out, int offset, int length)
          Fills the designated byte array, starting from byte at index offset, for a maximum of length bytes with the output of this generator instance.
abstract  void setup(java.util.Map attributes)
           
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

name

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


initialised

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


buffer

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


ndx

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

Constructor Detail

BasePRNG

protected BasePRNG(java.lang.String name)

Trivial constructor for use by concrete subclasses.

Method Detail

name

public java.lang.String name()
Description copied from interface: IRandom

Returns the canonical name of this instance.

Specified by:
name in interface IRandom

init

public void init(java.util.Map attributes)
Description copied from interface: IRandom

Initialises the pseudo-random number generator scheme with the appropriate attributes.

Specified by:
init in interface IRandom

nextByte

public byte nextByte()
              throws java.lang.IllegalStateException,
                     LimitReachedException
Description copied from interface: IRandom

Returns the next 8 bits of random data generated from this instance.

Specified by:
nextByte in interface IRandom

nextBytes

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

nextBytes

public void nextBytes(byte[] out,
                      int offset,
                      int length)
               throws java.lang.IllegalStateException,
                      LimitReachedException
Description copied from interface: IRandom

Fills the designated byte array, starting from byte at index offset, for a maximum of length bytes with the output of this generator instance.

Specified by:
nextBytes in interface IRandom

addRandomByte

public void addRandomByte(byte b)
Description copied from interface: IRandom

Supplement, or possibly replace, the random state of this PRNG with a random byte.

Implementations are not required to implement this method in any meaningful way; this may be a no-operation, and implementations may throw an java.lang.UnsupportedOperationException.

Specified by:
addRandomByte in interface IRandom

addRandomBytes

public void addRandomBytes(byte[] buffer)
Description copied from interface: IRandom

Supplement, or possibly replace, the random state of this PRNG with a sequence of new random bytes.

Implementations are not required to implement this method in any meaningful way; this may be a no-operation, and implementations may throw an java.lang.UnsupportedOperationException.

Specified by:
addRandomBytes in interface IRandom

addRandomBytes

public void addRandomBytes(byte[] buffer,
                           int offset,
                           int length)
Description copied from interface: IRandom

Supplement, or possibly replace, the random state of this PRNG with a sequence of new random bytes.

Implementations are not required to implement this method in any meaningful way; this may be a no-operation, and implementations may throw an java.lang.UnsupportedOperationException.

Specified by:
addRandomBytes in interface IRandom

isInitialised

public boolean isInitialised()

nextByteInternal

private byte nextByteInternal()
                       throws LimitReachedException

clone

public java.lang.Object clone()
                       throws java.lang.CloneNotSupportedException
Description copied from interface: IRandom

Returns a clone copy of this instance.

Specified by:
clone in interface IRandom

setup

public abstract void setup(java.util.Map attributes)

fillBlock

public abstract void fillBlock()
                        throws LimitReachedException