lava.security.des.spec
Class DesPermutation

java.lang.Object
  |
  +--lava.security.des.spec.DesPermutation

public final class DesPermutation

extends java.lang.Object

DES permutation tables.

Details: This class provides convenient access to all of the permutation functions described in the official DES specification. This class defines one variable for each permutation.

Since:

1999.08.04

Author:

Sharky

Field Summary

static DesPermutation	fkcp Final key compression permutation.
static DesPermutation	ftp Final text permutation.
static DesPermutation	ikcp Initial key compression permutation.
static DesPermutation	itp Initial text permutation.
static DesPermutation	pbp P box permutation.
static DesPermutation	tep Text expansion permutation.

Method Summary

int	getFipsValue(int fipsindex) Returns value from permutation table.
int	getReorderedValue(int bitindex) Returns value from reordered permutation table.
int	getTableSize() Returns table size.

Methods inherited from class java.lang.Object

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

Field Detail

ikcp

public static final DesPermutation ikcp

Initial key compression permutation.

Details: This instance describes the initial key compression permutation, identified in FIPS PUB 46-2 as "permuted choice 1" (PC-1).

fkcp

public static final DesPermutation fkcp

Final key compression permutation.

Details: This instance describes the final key compression permutation, identified in FIPS PUB 46-2 as "permuted choice 2" (PC-2).

itp

public static final DesPermutation itp

Initial text permutation.

Details: This instance describes the initial text permutation, which is identified in FIPS PUB 46-2 as the "initial permutation" (IP).

ftp

public static final DesPermutation ftp

Final text permutation.

Details: This instance describes the final text permutation, identified in FIPS PUB 46-2 as the "inverse of the initial permutation" (IP^-1).

tep

public static final DesPermutation tep

Text expansion permutation.

Details: This instance describes the text expansion permutation, identified in FIPS PUB 46-2 as the function "E" ("E bit-selection table").

pbp

public static final DesPermutation pbp

P box permutation.

Details: This instance describes the P box permutation, identified in FIPS PUB 46-2 as the "primitive function P".

Method Detail

getTableSize

public final int getTableSize()

Returns table size.

Details: This method returns the number of entries in the permutation table.

Returns:

the size

getFipsValue

public final int getFipsValue(int fipsindex)

Returns value from permutation table.

Details: This method returns an entry from the table. Both the index into the table and the returned value correspond to the FIPS bit numbering scheme. (The leftmost bit is bit number 1.) fipsindex is the index of the output bit, and the return value is the index of the input bit.

For example, if getFipsValue(7) returns 3, then bit 7 of the permutation function's output is the same as bit 3 of the permutation function's input.

Parameters:

fipsindex - the index of the output bit

Returns:

the index of the input bit

getReorderedValue

public final int getReorderedValue(int bitindex)

Returns value from reordered permutation table.

Details: This method returns an entry from the "reordered" table. By "reordered", we mean that bits are numbered as naturally as possible for software, with the right most bit indexed as "0" and the indeces increasing to the right. bitindex is the index of the output bit, and the return value is the index of the input bit.

For example, if getFipsValue(7) returns 3, then bit 7 of the permutation function's output is the same as bit 3 of the permutation function's input.

Parameters:

bitindex - the index of the output bit

Returns:

the index of the input bit