221 lines
7.0 KiB
Java
221 lines
7.0 KiB
Java
/* DESKeySpec -- Keys for DES.
|
|
Copyright (C) 2004 Free Software Foundation, Inc.
|
|
|
|
This file is part of GNU Classpath.
|
|
|
|
GNU Classpath is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; either version 2, or (at your option)
|
|
any later version.
|
|
|
|
GNU Classpath is distributed in the hope that it will be useful, but
|
|
WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with GNU Classpath; see the file COPYING. If not, write to the
|
|
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
|
|
02110-1301 USA.
|
|
|
|
Linking this library statically or dynamically with other modules is
|
|
making a combined work based on this library. Thus, the terms and
|
|
conditions of the GNU General Public License cover the whole
|
|
combination.
|
|
|
|
As a special exception, the copyright holders of this library give you
|
|
permission to link this library with independent modules to produce an
|
|
executable, regardless of the license terms of these independent
|
|
modules, and to copy and distribute the resulting executable under
|
|
terms of your choice, provided that you also meet, for each linked
|
|
independent module, the terms and conditions of the license of that
|
|
module. An independent module is a module which is not derived from
|
|
or based on this library. If you modify this library, you may extend
|
|
this exception to your version of the library, but you are not
|
|
obligated to do so. If you do not wish to do so, delete this
|
|
exception statement from your version. */
|
|
|
|
|
|
package javax.crypto.spec;
|
|
|
|
import java.security.InvalidKeyException;
|
|
import java.security.spec.KeySpec;
|
|
|
|
/**
|
|
* This class is a transparent wrapper for DES keys, which are arrays
|
|
* of 8 bytes.
|
|
*
|
|
* @author Casey Marshall (csm@gnu.org)
|
|
* @since 1.4
|
|
*/
|
|
public class DESKeySpec implements KeySpec
|
|
{
|
|
|
|
// Constants.
|
|
// ------------------------------------------------------------------------
|
|
|
|
/**
|
|
* The length of a DES key, in bytes.
|
|
*/
|
|
public static final int DES_KEY_LEN = 8;
|
|
|
|
/**
|
|
* The key bytes.
|
|
*/
|
|
private byte[] key;
|
|
|
|
// Constructors.
|
|
// ------------------------------------------------------------------------
|
|
|
|
/**
|
|
* Create a new DES key spec, copying the first 8 bytes from the
|
|
* byte array.
|
|
*
|
|
* @param key The key bytes.
|
|
* @throws java.security.InvalidKeyException If there are less than 8
|
|
* bytes in the array.
|
|
*/
|
|
public DESKeySpec(byte[] key) throws InvalidKeyException
|
|
{
|
|
this(key, 0);
|
|
}
|
|
|
|
/**
|
|
* Create a new DES key spec, starting at <code>offset</code> in
|
|
* the byte array. The first 8 bytes starting at <code>offset</code>
|
|
* are copied.
|
|
*
|
|
* @param key The key bytes.
|
|
* @param offset The offset into the byte array at which to begin.
|
|
* @throws java.security.InvalidKeyException If there are less than 8
|
|
* bytes starting at <code>offset</code>.
|
|
*/
|
|
public DESKeySpec(byte[] key, int offset) throws InvalidKeyException
|
|
{
|
|
if (key.length - offset < DES_KEY_LEN)
|
|
{
|
|
throw new InvalidKeyException("DES keys must be 8 bytes long");
|
|
}
|
|
this.key = new byte[DES_KEY_LEN];
|
|
System.arraycopy(key, offset, this.key, 0, DES_KEY_LEN);
|
|
}
|
|
|
|
// Class methods.
|
|
// ------------------------------------------------------------------------
|
|
|
|
/**
|
|
* Returns whether or not the given key is <i>parity adjusted</i>;
|
|
* i.e. every byte in the key has an odd number of "1" bits.
|
|
*
|
|
* @param key The key bytes, considered between <code>[offset,
|
|
* offset+7]</code>
|
|
* @param offset The offset into the byte array at which to begin.
|
|
* @return True if all bytes have an odd number of "1" bits.
|
|
* @throws java.security.InvalidKeyException If there are not enough
|
|
* bytes in the array.
|
|
*/
|
|
public static boolean isParityAdjusted(byte[] key, int offset)
|
|
throws InvalidKeyException
|
|
{
|
|
if (key.length - offset < DES_KEY_LEN)
|
|
{
|
|
throw new InvalidKeyException("DES keys must be 8 bytes long");
|
|
}
|
|
boolean parity = false;
|
|
boolean oddbits = false;
|
|
for (int i = 0; i < DES_KEY_LEN; i++)
|
|
{
|
|
oddbits = false;
|
|
for (int j = 0; j < 8; j++)
|
|
{
|
|
oddbits ^= (key[i+offset] & 1 << j) != 0;
|
|
}
|
|
parity &= oddbits;
|
|
}
|
|
return parity;
|
|
}
|
|
|
|
/**
|
|
* One-half of the weak and semiweak DES keys (the other half are the
|
|
* complements of these).
|
|
*/
|
|
private static final byte[][] WEAK_KEYS = new byte[][] {
|
|
{ 0, 0, 0, 0, 0, 0, 0, 0 }, // 0000 0000 0000 0000
|
|
{ -1, -1, -1, -1, 0, 0, 0, 0 }, // ffff ffff 0000 0000
|
|
{ 1, 1, 1, 1, 1, 1, 1, 1 }, // 0101 0101 0101 0101
|
|
{ 31, 31, 31, 31, 14, 14, 14, 14 }, // 1f1f 1f1f 0e0e 0e0e
|
|
{ 1, -2, 1, -2, 1, -2, 1, -2 }, // 01fe 01fe 01fe 01fe
|
|
{ 31, -32, 31, -32, -32, 31, -32, 31 }, // 1fe0 1fe0 0e1f 0e1f
|
|
{ 1, -32, 1, -32, 1, -15, 1, -15 }, // 01e0 01e0 01f1 01f1
|
|
{ 31, -2, 31, -2, 14, -2, 14, -2 }, // 1ffe 1ffe 0efe 0efe
|
|
{ 1, 31, 1, 31, 1, 14, 1, 14 }, // 011f 011f 010e 010e
|
|
{ -32, -2, -32, -2, -15, -2, -15, -2 }, // e0fe e0fe f1fe f1fe
|
|
};
|
|
|
|
/**
|
|
* Tests if the bytes between <code>[offset, offset+7]</code>
|
|
* constitute a weak or semi-weak DES key.
|
|
*
|
|
* @param key The key bytes to check.
|
|
* @param offset The offset in the byte array to start.
|
|
* @return true If the key bytes are a weak key.
|
|
*/
|
|
public static boolean isWeak(byte[] key, int offset)
|
|
throws InvalidKeyException
|
|
{
|
|
if (key.length - offset < DES_KEY_LEN)
|
|
{
|
|
throw new InvalidKeyException("DES keys must be 8 bytes long");
|
|
}
|
|
for (int i = 0; i < WEAK_KEYS.length; i++)
|
|
{
|
|
if (equalsOrComplementEquals(key, offset, WEAK_KEYS[i]))
|
|
{
|
|
return true;
|
|
}
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* This method returns true if the first 8 bytes starting at
|
|
* <code>off</code> in <code>a</code> equal the first 8 bytes in
|
|
* <code>b</code>, or equal the <i>complement</i> of the first 8 bytes
|
|
* in <code>b</code>.
|
|
*
|
|
* @param a The first byte array.
|
|
* @param off The index into the first byte array.
|
|
* @param b The second byte array.
|
|
* @return <code>a == b || a == ~b</code>
|
|
*/
|
|
private static boolean equalsOrComplementEquals(byte[] a, int off, byte[] b)
|
|
{
|
|
boolean result = true;
|
|
for (int i = 0; i < DES_KEY_LEN; i++)
|
|
{
|
|
result &= a[off+i] == b[i];
|
|
}
|
|
if (result) return true;
|
|
result = true;
|
|
for (int i = 0; i < DES_KEY_LEN; i++)
|
|
{
|
|
result &= a[off+i] == (~b[i]);
|
|
}
|
|
return result;
|
|
}
|
|
|
|
// Instance methods.
|
|
// ------------------------------------------------------------------------
|
|
|
|
/**
|
|
* Return the key as a byte array. This method does not copy the byte
|
|
* array.
|
|
*
|
|
* @return The key bytes.
|
|
*/
|
|
public byte[] getKey()
|
|
{
|
|
return key;
|
|
}
|
|
}
|