javax.crypto.spec
Class DESKeySpec

java.lang.Object
  |
  +--javax.crypto.spec.DESKeySpec

public class DESKeySpec

extends java.lang.Object

implements KeySpec

DES key specification.

Attention: This is not a SUN implementation!

This class has been developed by IAIK according to the documentation publicly available.
For SUNīs documentation of this class see http://java.sun.com/security/JCE1.2/spec/apidoc/index.html

This class represents a DES key specification.

A key specification is a transparent representation of the key material constituting the key. For a DES key, this class specifies the underlying byte material constituting the key.

See Also:

KeySpec

Field Summary

static int

DES_KEY_LEN

Constructor Summary

DESKeySpec(byte[] key)
Creates a DES key specification by using the first 8 bytes of the supplied byte array as the DES key.

DESKeySpec(byte[] key, int offset)
Creates a DES key specification by using 8 bytes of the supplied byte array as DES key, beginning at the given offset.

Method Summary

byte[]	getKey() Returns the inherent DES key as byte representation.
static boolean	isParityAdjusted(byte[] key, int offset) Checks if the DES key, supplied in a byte array beginning at the given offset, is parity-adjusted.
static boolean	isWeak(byte[] key, int offset) Checks if the given DES key material, supplied within a byte array beginning at the given position, represents a weak or semi-weak DES key.

Methods inherited from class java.lang.Object

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

Field Detail

DES_KEY_LEN

public static final int DES_KEY_LEN

Constructor Detail

DESKeySpec

public DESKeySpec(byte[] key)
           throws InvalidKeyException

Creates a DES key specification by using the first 8 bytes of the supplied byte array as the DES key.

Parameters:

key - the byte array holding the DES key

Throws:

InvalidKeyException - if the given key is shorter than 8 bytes

DESKeySpec

public DESKeySpec(byte[] key,
                  int offset)
           throws InvalidKeyException

Creates a DES key specification by using 8 bytes of the supplied byte array as DES key, beginning at the given offset.

Parameters:

key - the byte array holding the DES key

offset - the offset indicating the start position within the input key byte array

Throws:

InvalidKeyException - if the given key, beginning at offset, is shorter than 8 bytes

Method Detail

getKey

public byte[] getKey()

Returns the inherent DES key as byte representation.

Returns:

the DES key

isWeak

public static boolean isWeak(byte[] key,
                             int offset)
                      throws InvalidKeyException

Checks if the given DES key material, supplied within a byte array beginning at the given position, represents a weak or semi-weak DES key. Due to the way, the DES algorithm generates sub-keys for the several DES rounds, some initial keys may be classified as weak or semi-weak kyes reducing the security of the DES cipher (see "Applied Cryptography", Bruce Schneier, ISBN 0-471-59756-2).

Parameters:

key - the byte array holding the DES key to be checked

offset - the offset indicating the start position within the given byte array from which the key has to be read

Returns:

true if the given DES key material represents a weak or semi-weak DES key, false if the represented key is a strong one.

Throws:

InvalidKeyException - if the given key, beginning at offset, is shorter than 8 bytes

isParityAdjusted

public static boolean isParityAdjusted(byte[] key,
                                       int offset)
                                throws InvalidKeyException

Checks if the DES key, supplied in a byte array beginning at the given offset, is parity-adjusted.

Parameters:

key - the byte array holding the DES key

offset - the offset indicating the start position within the input key byte array

Returns:

true if the given DES key is parity-adjusted, false otherwise

Throws:

InvalidKeyException - if the given key, beginning at offset, is shorter than 8 bytes