public class ICMGenerator
extends tr.gov.tubitak.uekae.esya.api.common.crypto.BasePRNG
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:
256 ** BLOCK_INDEX_LENGTH
. The number of segments MUST NOT
exceed 256 ** SEGMENT_INDEX_LENGTH
. These restrictions ensure
the uniqueness of each block cipher input.SEGMENT_LENGTH
octets; this value
MUST NOT exceed the value (256 ** BLOCK_INDEX_LENGTH) *
BLOCK_LENGTH
.SEGMENT_INDEX_LENGTH
and
BLOCK_INDEX_LENGTH
MUST NOT exceed BLOCK_LENGTH
/ 2
. This requirement protects the ICM keystream generator from
potentially failing to be pseudorandom.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:
Modifier and Type | Field and Description |
---|---|
static java.lang.String |
BLOCK_INDEX_LENGTH
Property name of ICM's block index length.
|
static java.lang.String |
CIPHER
Property name of underlying block cipher for this ICM generator.
|
static java.lang.String |
OFFSET
Property name of ICM's offset.
|
static java.lang.String |
SEGMENT_INDEX
Property name of ICM's segment index.
|
static java.lang.String |
SEGMENT_INDEX_LENGTH
Property name of ICM's segment index length.
|
Constructor and Description |
---|
ICMGenerator()
Trivial 0-arguments constructor.
|
Modifier and Type | Method and Description |
---|---|
java.lang.Object |
clone() |
void |
fillBlock() |
void |
setup(java.util.Map attributes) |
public static final java.lang.String CIPHER
public static final java.lang.String BLOCK_INDEX_LENGTH
public static final java.lang.String SEGMENT_INDEX_LENGTH
public static final java.lang.String OFFSET
public static final java.lang.String SEGMENT_INDEX
public java.lang.Object clone()
clone
in interface tr.gov.tubitak.uekae.esya.api.common.crypto.IRandom
clone
in class tr.gov.tubitak.uekae.esya.api.common.crypto.BasePRNG
public void setup(java.util.Map attributes)
setup
in class tr.gov.tubitak.uekae.esya.api.common.crypto.BasePRNG
public void fillBlock() throws tr.gov.tubitak.uekae.esya.api.common.crypto.LimitReachedException
fillBlock
in class tr.gov.tubitak.uekae.esya.api.common.crypto.BasePRNG
tr.gov.tubitak.uekae.esya.api.common.crypto.LimitReachedException
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