Package gnu.crypto.prng

Class 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

    • Constructor Detail

      • FortunaStandalone

        public FortunaStandalone()

    • Method Detail

      • allocBuffer

        protected void allocBuffer()
        Unused, see AsyncFortunaStandalone

      • seed

        public void seed​(byte[] val)
        Unused, see AsyncFortunaStandalone

      • 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.