Package io.github.olyutorskii.aletojio.bijection

Class Pbox32

java.lang.Object

io.github.olyutorskii.aletojio.bijection.Pbox32

All Implemented Interfaces:

RndInt32

public class Pbox32
extends Object
implements RndInt32

P-box diffusion by bit permutation.

Takes a 32-bit integer as input and outputs a diffused 32-bit integer.

See Also:

• Permutation box (Wikipedia)
• Confusion_and_diffusion (Wikipedia)
• Substitution-permutation network (SPN) (Wikipedia)

Constructor Summary

Constructors

Constructor	Description
Pbox32(RndInt32 rndArg)	Constructor.
Pbox32(RndInt32 rndArg, int[] permuteArg)	Constructor.

Method Summary

Modifier and Type	Method	Description
static void	checkPbox(int[] permuteArg)	Check P-box table.
static int	mapPermutation(int iVal)	Map int value with default P-box table.
static int	mapTable(int iVal, int[] table)	Map int value with specified P-box table.
int	nextInt32()	Return next random number as 32bit int with random sign-bit.

Methods inherited from class java.lang.Object

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

Constructor Details

Pbox32

public Pbox32(RndInt32 rndArg)
       throws NullPointerException,
IllegalArgumentException

Constructor.

Default P-box tabel is used. p[N] = (17 + 19 * N) mod 32

Parameters:

rndArg - random source

Throws:

NullPointerException

IllegalArgumentException

Pbox32

public Pbox32(RndInt32 rndArg,
 int[] permuteArg)
       throws NullPointerException,
IllegalArgumentException

Constructor.

P-box table length must be 32.

P-box table must be bijection. (minimal perfect hash function)

(permuteArg[31] = 7) means copying bit from bit-31 to bit-7.

Parameters:

rndArg - random source

permuteArg - P-box bit-permutation table

Throws:

NullPointerException - null argument

IllegalArgumentException - invalid P-box

Method Details

mapPermutation

public static int mapPermutation(int iVal)

Map int value with default P-box table.

Default P-box tabel is used. p[N] = (17 + 19 * N) mod 32

Parameters:

iVal - int value

Returns:

mapped value

mapTable

public static int mapTable(int iVal,
 int[] table)

Map int value with specified P-box table.

There is no bijection check.

Parameters:

iVal - int value

table - P-box table

Returns:

mapped value

Throws:

NullPointerException - table is null

checkPbox

public static void checkPbox(int[] permuteArg)
                      throws NullPointerException,
IllegalArgumentException

Check P-box table.

P-box table length must be 32.

P-box table must be bijection. (minimal perfect hash function)

(permuteArg[31] = 7) means copying bit from bit-31 to bit-7.

Parameters:

permuteArg - P-box table

Throws:

NullPointerException - null argument

IllegalArgumentException - size unmatch or not bijection detected

nextInt32

public int nextInt32()

Return next random number as 32bit int with random sign-bit.

Specified by:

nextInt32 in interface RndInt32

Returns:

random number