DESKeySpec

AI-generated Key Takeaways

• DESKeySpec specifies a DES key using 8 bytes of key material.

• It provides constructors to create a DESKeySpec from a byte array, with or without an offset.

• Methods are included to retrieve the key material and check for parity adjustment and key weakness.

• The constant DES_KEY_LEN defines the length of a DES key in bytes, which is 8.

public class DESKeySpec extends Object
implements KeySpec

This class specifies a DES key.

Constant Summary

int

DES_KEY_LEN

The constant which defines the length of a DES key in bytes.

Public Constructor Summary

	DESKeySpec(byte[] key) Creates a DESKeySpec object using the first 8 bytes in key as the key material for the DES key.
	DESKeySpec(byte[] key, int offset) Creates a DESKeySpec object using the first 8 bytes in key, beginning at offset inclusive, as the key material for the DES key.

Public Method Summary

byte[]	getKey() Returns the DES key material.
static boolean	isParityAdjusted(byte[] key, int offset) Checks if the given DES key material, starting at offset inclusive, is parity-adjusted.
static boolean	isWeak(byte[] key, int offset) Checks if the given DES key material is weak or semi-weak.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Constants

public static final int DES_KEY_LEN

The constant which defines the length of a DES key in bytes.

Constant Value: 8

Public Constructors

public DESKeySpec (byte[] key)

Creates a DESKeySpec object using the first 8 bytes in key as the key material for the DES key.

The bytes that constitute the DES key are those between key[0] and key[7] inclusive.

Parameters

key	the buffer with the DES key material. The first 8 bytes of the buffer are copied to protect against subsequent modification.

Throws

NullPointerException	if the given key material is null
InvalidKeyException	if the given key material is shorter than 8 bytes.

public DESKeySpec (byte[] key, int offset)

Creates a DESKeySpec object using the first 8 bytes in key, beginning at offset inclusive, as the key material for the DES key.

The bytes that constitute the DES key are those between key[offset] and key[offset+7] inclusive.

Parameters

key	the buffer with the DES key material. The first 8 bytes of the buffer beginning at offset inclusive are copied to protect against subsequent modification.
offset	the offset in key, where the DES key material starts.

Throws

NullPointerException	if the given key material is null
InvalidKeyException	if the given key material, starting at offset inclusive, is shorter than 8 bytes.

Public Methods

public byte[] getKey ()

Returns the DES key material.

Returns

• the DES key material. Returns a new array each time this method is called.

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

Checks if the given DES key material, starting at offset inclusive, is parity-adjusted.

Parameters

key	the buffer with the DES key material.
offset	the offset in key, where the DES key material starts.

Returns

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

Throws

InvalidKeyException	if the given key material is null, or starting at offset inclusive, is shorter than 8 bytes.

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

Checks if the given DES key material is weak or semi-weak.

Parameters

key	the buffer with the DES key material.
offset	the offset in key, where the DES key material starts.

Returns

• true if the given DES key material is weak or semi-weak, false otherwise.

Throws

InvalidKeyException	if the given key material is null, or starting at offset inclusive, is shorter than 8 bytes.