com.mindbright.util
Class SecureRandomAndPad

java.lang.Object
  java.util.Random
      java.security.SecureRandom
          com.mindbright.util.SecureRandomAndPad

All Implemented Interfaces:

java.io.Serializable

public class SecureRandomAndPad
extends java.security.SecureRandom

Class for generating both random bytes and pad bytes. The pad bytes are also pseudo-random but generated by a different algorithm (arcfour) and uses a different seed.

See Also:

Serialized Form

Constructor Summary

SecureRandomAndPad()
Simple constructor.

SecureRandomAndPad(byte[] seed)

SecureRandomAndPad(java.security.SecureRandom random)
Creates an instance which uses the given random number generator.

Method Summary

byte[]	generateSeed(int numBytes) Generate random seed bytes.
void	nextBytes(byte[] bytes) Fills the given array with random bytes.
void	nextPadBytes(byte[] bytes, int off, int len) Get a number of pad bytes.
void	setPadSeed(byte[] seed) Seed the pad generator.
void	setSeed(byte[] seed) Seeds the random number generator.

Methods inherited from class java.security.SecureRandom

getAlgorithm, getInstance, getInstance, getInstance, getProvider, getSeed, next, setSeed

Methods inherited from class java.util.Random

nextBoolean, nextDouble, nextFloat, nextGaussian, nextInt, nextInt, nextLong

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

SecureRandomAndPad

public SecureRandomAndPad()

Simple constructor.

SecureRandomAndPad

public SecureRandomAndPad(byte[] seed)

SecureRandomAndPad

public SecureRandomAndPad(java.security.SecureRandom random)

Creates an instance which uses the given random number generator.

Parameters:

random - underlying random number generator

Method Detail

setPadSeed

public void setPadSeed(byte[] seed)

Seed the pad generator. This should be called once before extracting pad bytes. Otherwise the pad bytes will be nonrandom.

Parameters:

seed - array of random data which is used to seed the generator

nextPadBytes

public void nextPadBytes(byte[] bytes,
                         int off,
                         int len)

Get a number of pad bytes.

Parameters:

bytes - array into which the bytes should be stored

off - offset to first byte to store in array

len - number of pad bytes to store

generateSeed

public byte[] generateSeed(int numBytes)

Generate random seed bytes. These bytes are generated by the normal random number generator.

Overrides:

generateSeed in class java.security.SecureRandom

Parameters:

numBytes - how many bytes to generate

Returns:

an array of random bytes

nextBytes

public void nextBytes(byte[] bytes)

Fills the given array with random bytes.

Overrides:

nextBytes in class java.security.SecureRandom

Parameters:

bytes - array to fill with random bytes

setSeed

public void setSeed(byte[] seed)

Seeds the random number generator.

Overrides:

setSeed in class java.security.SecureRandom

Parameters:

seed - array of random data which is used to seed the generator