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gnu.javax.crypto.prng
Class Fortuna.Generator  view Fortuna.Generator download Fortuna.Generator.java

java.lang.Object
  extended bygnu.java.security.prng.BasePRNG
      extended bygnu.javax.crypto.prng.Fortuna.Generator
All Implemented Interfaces:
java.lang.Cloneable, gnu.java.security.prng.IRandom
Enclosing class:
Fortuna

public static class Fortuna.Generator
extends gnu.java.security.prng.BasePRNG
implements java.lang.Cloneable

The Fortuna generator function. The generator is a PRNG in its own right; Fortuna itself is basically a wrapper around this generator that manages reseeding in a secure way.


Field Summary
private  gnu.javax.crypto.cipher.IBlockCipher cipher
           
private  byte[] counter
           
private  gnu.java.security.hash.IMessageDigest hash
           
private  byte[] key
           
private static int LIMIT
           
private  boolean seeded
           
 
Fields inherited from class gnu.java.security.prng.BasePRNG
buffer, initialised, name, ndx
 
Constructor Summary
Fortuna.Generator(gnu.javax.crypto.cipher.IBlockCipher cipher, gnu.java.security.hash.IMessageDigest hash)
           
 
Method Summary
 void addRandomByte(byte b)
          Supplement, or possibly replace, the random state of this PRNG with a random byte.
 void addRandomBytes(byte[] seed, int offset, int length)
          Supplement, or possibly replace, the random state of this PRNG with a sequence of new random bytes.
 void fillBlock()
           
private  void incrementCounter()
          Increment `counter' as a sixteen-byte little-endian unsigned integer by one.
 byte nextByte()
          Returns the next 8 bits of random data generated from this instance.
 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.
private  void resetKey()
          Resets the cipher's key.
 void setup(java.util.Map attributes)
           
 
Methods inherited from class gnu.java.security.prng.BasePRNG
addRandomBytes, clone, init, isInitialised, name, nextBytes
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

LIMIT

private static final int LIMIT
See Also:
Constant Field Values

cipher

private final gnu.javax.crypto.cipher.IBlockCipher cipher

hash

private final gnu.java.security.hash.IMessageDigest hash

counter

private final byte[] counter

key

private final byte[] key

seeded

private boolean seeded
Constructor Detail

Fortuna.Generator

public Fortuna.Generator(gnu.javax.crypto.cipher.IBlockCipher cipher,
                         gnu.java.security.hash.IMessageDigest hash)
Method Detail

nextByte

public byte nextByte()
Description copied from interface: gnu.java.security.prng.IRandom

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

Specified by:
nextByte in interface gnu.java.security.prng.IRandom

nextBytes

public void nextBytes(byte[] out,
                      int offset,
                      int length)
Description copied from interface: gnu.java.security.prng.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 gnu.java.security.prng.IRandom

addRandomByte

public void addRandomByte(byte b)
Description copied from interface: gnu.java.security.prng.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 gnu.java.security.prng.IRandom

addRandomBytes

public void addRandomBytes(byte[] seed,
                           int offset,
                           int length)
Description copied from interface: gnu.java.security.prng.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 gnu.java.security.prng.IRandom

fillBlock

public void fillBlock()

setup

public void setup(java.util.Map attributes)

resetKey

private void resetKey()
Resets the cipher's key. This is done after every reseed, which combines the old key and the seed, and processes that throigh the hash function.


incrementCounter

private void incrementCounter()
Increment `counter' as a sixteen-byte little-endian unsigned integer by one.