gnu.crypto.prng

Class FortunaStandalone

java.lang.Object

gnu.crypto.prng.BasePRNGStandalone

gnu.crypto.prng.FortunaStandalone

All Implemented Interfaces:

IRandomStandalone, Serializable, Cloneable

Direct Known Subclasses:

AsyncFortunaStandalone

public class FortunaStandalone
extends BasePRNGStandalone
implements Serializable

The Fortuna continuously-seeded pseudo-random number generator. This generator is composed of two major pieces: the entropy accumulator and the generator function. The former takes in random bits and incorporates them into the generator's state. The latter takes this base entropy and generates pseudo-random bits from it.

There are some things users of this class must be aware of:

Adding Random Data

This class does not do any polling of random sources, but rather provides an interface for adding random events. Applications that use this code must provide this mechanism. We use this design because an application writer who knows the system he is targeting is in a better position to judge what random data is available.

Storing the Seed

This class implements Serializable in such a way that it writes a 64 byte seed to the stream, and reads it back again when being deserialized. This is the extent of seed file management, however, and those using this class are encouraged to think deeply about when, how often, and where to store the seed.

References:

• Niels Ferguson and Bruce Schneier, Practical Cryptography, pp. 155--184. Wiley Publishing, Indianapolis. (2003 Niels Ferguson and Bruce Schneier). ISBN 0-471-22357-3.

Modified by jrandom for I2P to use a standalone gnu-crypto SHA256, Cryptix's AES, to strip out some unnecessary dependencies and increase the buffer size. Renamed from Fortuna to FortunaStandalone so it doesn't conflict with the gnu-crypto implementation, which has been imported into GNU/classpath NOTE: As of 0.8.8, uses the java.security.MessageDigest instead of GNU Sha256Standalone

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected IRandomStandalone	generator
protected long	lastReseed
(package private) static int	MIN_POOL_SIZE
(package private) static int	NUM_POOLS
protected int	pool0Count
protected MessageDigest[]	pools null if using DevRandom
protected int	reseedCount
static String	SEED

Fields inherited from class gnu.crypto.prng.BasePRNGStandalone

buffer, initialised, name, ndx

Constructor Summary

Constructors

Constructor and Description
FortunaStandalone()
FortunaStandalone(boolean useDevRandom)

Method Summary

Modifier and Type	Method and Description
void	addRandomByte(byte b) Supplement, or possibly replace, the random state of this PRNG with a random byte.
void	addRandomBytes(byte[] buf, int offset, int length) Supplement, or possibly replace, the random state of this PRNG with a sequence of new random bytes.
void	fillBlock() Unused, see AsyncFortunaStandalone
void	seed(byte[] val) Unused, see AsyncFortunaStandalone
void	setup(Map<String,byte[]> attributes)

Methods inherited from class gnu.crypto.prng.BasePRNGStandalone

addRandomBytes, clone, init, isInitialised, name, nextByte, nextBytes, nextBytes

Methods inherited from class java.lang.Object

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

Field Detail

generator

protected final IRandomStandalone generator

lastReseed

protected long lastReseed

MIN_POOL_SIZE

static final int MIN_POOL_SIZE

See Also:

Constant Field Values

NUM_POOLS

static final int NUM_POOLS

See Also:

Constant Field Values

pool0Count

protected int pool0Count

pools

protected final MessageDigest[] pools

null if using DevRandom

reseedCount

protected int reseedCount

SEED

public static final String SEED

See Also:

Constant Field Values

Constructor Detail

FortunaStandalone

public FortunaStandalone()

FortunaStandalone

public FortunaStandalone(boolean useDevRandom)

Method Detail

addRandomByte

public void addRandomByte(byte b)

Description copied from interface: IRandomStandalone

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 UnsupportedOperationException.

Specified by:

addRandomByte in interface IRandomStandalone

Overrides:

addRandomByte in class BasePRNGStandalone

Parameters:

b - The byte to add.

addRandomBytes

public void addRandomBytes(byte[] buf,
                           int offset,
                           int length)

Description copied from interface: IRandomStandalone

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 UnsupportedOperationException.

Specified by:

addRandomBytes in interface IRandomStandalone

Overrides:

addRandomBytes in class BasePRNGStandalone

Parameters:

buf - The buffer of new random bytes to add.

offset - The offset from whence to begin reading random bytes.

length - The number of random bytes to add.

fillBlock

public void fillBlock()

Unused, see AsyncFortunaStandalone

Specified by:

fillBlock in class BasePRNGStandalone

seed

public void seed(byte[] val)

Unused, see AsyncFortunaStandalone

setup

public void setup(Map<String,byte[]> attributes)

Specified by:

setup in class BasePRNGStandalone