gnu.crypto.prng

Class ICMGenerator

Implemented Interfaces:
Cloneable, IRandom

public class ICMGenerator
extends BasePRNG
implements Cloneable

Counter Mode is a way to define a pseudorandom keystream generator using a block cipher. The keystream can be used for additive encryption, key derivation, or any other application requiring pseudorandom data.

In ICM, the keystream is logically broken into segments. Each segment is identified with a segment index, and the segments have equal lengths. This segmentation makes ICM especially appropriate for securing packet-based protocols.

This implementation adheres to the definition of the ICM keystream generation function that allows for any symetric key block cipher algorithm (initialisation parameter gnu.crypto.prng.icm.cipher.name taken to be an instance of String) to be used. If such a parameter is not defined/included in the initialisation Map, then the "Rijndael" algorithm is used. Furthermore, if the initialisation parameter gnu.crypto.cipher.block.size (taken to be a instance of Integer) is missing or undefined in the initialisation Map, then the cipher's default block size is used.

The practical limits and constraints of such generator are:

NOTE: Rijndael is used as the default symmetric key block cipher algorithm because, with its default block and key sizes, it is the AES. Yet being Rijndael, the algorithm offers more versatile block and key sizes which may prove to be useful for generating longer key streams.

References:

  1. Integer Counter Mode, David A. McGrew.
Version:
$Revision: 1.13 $

Field Summary

static String
BLOCK_INDEX_LENGTH
Property name of ICM's block index length.
static String
CIPHER
Property name of underlying block cipher for this ICM generator.
static String
OFFSET
Property name of ICM's offset.
static String
SEGMENT_INDEX
Property name of ICM's segment index.
static String
SEGMENT_INDEX_LENGTH
Property name of ICM's segment index length.

Fields inherited from class gnu.crypto.prng.BasePRNG

buffer, initialised, name, ndx

Constructor Summary

ICMGenerator()
Trivial 0-arguments constructor.

Method Summary

void
fillBlock()
void
setup(Map attributes)

Methods inherited from class gnu.crypto.prng.BasePRNG

addRandomByte, addRandomBytes, addRandomBytes, clone, fillBlock, init, isInitialised, name, nextByte, nextBytes, nextBytes, setup

Field Details

BLOCK_INDEX_LENGTH

public static final String BLOCK_INDEX_LENGTH
Property name of ICM's block index length.

CIPHER

public static final String CIPHER
Property name of underlying block cipher for this ICM generator.

OFFSET

public static final String OFFSET
Property name of ICM's offset.

SEGMENT_INDEX

public static final String SEGMENT_INDEX
Property name of ICM's segment index.

SEGMENT_INDEX_LENGTH

public static final String SEGMENT_INDEX_LENGTH
Property name of ICM's segment index length.

Constructor Details

ICMGenerator

public ICMGenerator()
Trivial 0-arguments constructor.

Method Details

fillBlock

public void fillBlock()
            throws LimitReachedException
Overrides:
fillBlock in interface BasePRNG

setup

public void setup(Map attributes)
Overrides:
setup in interface BasePRNG

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