/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package javax.crypto.spec;
import java.security.InvalidKeyException;
import java.security.spec.KeySpec;
/**
* The key specification for a DES key.
*/
public class DESKeySpec implements KeySpec {
/**
* The length of a DES key in bytes.
*/
public static final int DES_KEY_LEN = 8;
private final byte[] key;
// DES weak and semi-weak keys
// Got from:
// FIP PUB 74
// FEDERAL INFORMATION PROCESSING STANDARDS PUBLICATION 1981
// GUIDELINES FOR IMPLEMENTING AND USING THE NBS DATA ENCRYPTION STANDARD
// http://www.dice.ucl.ac.be/crypto/standards/fips/fip74/fip74-1.pdf
private static final byte[][] SEMIWEAKS = {
{(byte) 0xE0, (byte) 0x01, (byte) 0xE0, (byte) 0x01,
(byte) 0xF1, (byte) 0x01, (byte) 0xF1, (byte) 0x01},
{(byte) 0x01, (byte) 0xE0, (byte) 0x01, (byte) 0xE0,
(byte) 0x01, (byte) 0xF1, (byte) 0x01, (byte) 0xF1},
{(byte) 0xFE, (byte) 0x1F, (byte) 0xFE, (byte) 0x1F,
(byte) 0xFE, (byte) 0x0E, (byte) 0xFE, (byte) 0x0E},
{(byte) 0x1F, (byte) 0xFE, (byte) 0x1F, (byte) 0xFE,
(byte) 0x0E, (byte) 0xFE, (byte) 0x0E, (byte) 0xFE},
{(byte) 0xE0, (byte) 0x1F, (byte) 0xE0, (byte) 0x1F,
(byte) 0xF1, (byte) 0x0E, (byte) 0xF1, (byte) 0x0E},
{(byte) 0x1F, (byte) 0xE0, (byte) 0x1F, (byte) 0xE0,
(byte) 0x0E, (byte) 0xF1, (byte) 0x0E, (byte) 0xF1},
{(byte) 0x01, (byte) 0xFE, (byte) 0x01, (byte) 0xFE,
(byte) 0x01, (byte) 0xFE, (byte) 0x01, (byte) 0xFE},
{(byte) 0xFE, (byte) 0x01, (byte) 0xFE, (byte) 0x01,
(byte) 0xFE, (byte) 0x01, (byte) 0xFE, (byte) 0x01},
{(byte) 0x01, (byte) 0x1F, (byte) 0x01, (byte) 0x1F,
(byte) 0x01, (byte) 0x0E, (byte) 0x01, (byte) 0x0E},
{(byte) 0x1F, (byte) 0x01, (byte) 0x1F, (byte) 0x01,
(byte) 0x0E, (byte) 0x01, (byte) 0x0E, (byte) 0x01},
{(byte) 0xE0, (byte) 0xFE, (byte) 0xE0, (byte) 0xFE,
(byte) 0xF1, (byte) 0xFE, (byte) 0xF1, (byte) 0xFE},
{(byte) 0xFE, (byte) 0xE0, (byte) 0xFE, (byte) 0xE0,
(byte) 0xFE, (byte) 0xF1, (byte) 0xFE, (byte) 0xF1},
{(byte) 0x01, (byte) 0x01, (byte) 0x01, (byte) 0x01,
(byte) 0x01, (byte) 0x01, (byte) 0x01, (byte) 0x01},
{(byte) 0xFE, (byte) 0xFE, (byte) 0xFE, (byte) 0xFE,
(byte) 0xFE, (byte) 0xFE, (byte) 0xFE, (byte) 0xFE},
{(byte) 0xE0, (byte) 0xE0, (byte) 0xE0, (byte) 0xE0,
(byte) 0xF1, (byte) 0xF1, (byte) 0xF1, (byte) 0xF1},
{(byte) 0x1F, (byte) 0x1F, (byte) 0x1F, (byte) 0x1F,
(byte) 0x0E, (byte) 0x0E, (byte) 0x0E, (byte) 0x0E},
};
/**
* Creates a new <code>DESKeySpec</code> from the first 8 bytes of the
* specified key data.
*
* @param key
* the key data.
* @throws InvalidKeyException
* if the length of the specified key data is less than 8.
*/
public DESKeySpec(byte[] key) throws InvalidKeyException {
this(key, 0);
}
/**
* Creates a new <code>DESKeySpec</code> from the first 8 bytes of the
* specified key data starting at <code>offset</code>.
*
* @param key
* the key data
* @param offset
* the offset to start at.
* @throws InvalidKeyException
* if the length of the specified key data starting at offset is
* less than 8.
*/
public DESKeySpec(byte[] key, int offset) throws InvalidKeyException {
if (key == null) {
throw new NullPointerException("key == null");
}
if (key.length - offset < DES_KEY_LEN) {
throw new InvalidKeyException("key too short");
}
this.key = new byte[DES_KEY_LEN];
System.arraycopy(key, offset, this.key, 0, DES_KEY_LEN);
}
/**
* Returns a copy of the key.
*
* @return a copy of the key.
*/
public byte[] getKey() {
byte[] result = new byte[DES_KEY_LEN];
System.arraycopy(this.key, 0, result, 0, DES_KEY_LEN);
return result;
}
/**
* Returns whether the specified key data starting at <code>offset</code> is
* <i>parity-adjusted</i>.
*
* @param key
* the key data.
* @param offset
* the offset to start checking at.
* @return {@code true} if the specified key data is parity-adjusted,
* {@code false} otherwise.
* @throws InvalidKeyException
* if the length of the key data starting at offset is less than
* 8, or the key is null.
*/
public static boolean isParityAdjusted(byte[] key, int offset) throws InvalidKeyException {
if (key == null) {
throw new InvalidKeyException("key == null");
}
if (key.length - offset < DES_KEY_LEN) {
throw new InvalidKeyException("key too short");
}
int byteKey = 0;
for (int i = offset; i < DES_KEY_LEN; i++) {
byteKey = key[i];
byteKey ^= byteKey >> 1;
byteKey ^= byteKey >> 2;
byteKey ^= byteKey >> 4;
if ((byteKey & 1) == 0) {
return false;
}
}
return true;
}
/**
* Returns whether the specified key data starting at <code>offset</code> is
* weak or semi-weak.
*
* @param key
* the key data.
* @param offset
* the offset to start checking at.
* @return {@code true} if the specified key data is weak or semi-weak.
* @throws InvalidKeyException
* if the length of the key data starting at offset is less than
* 8, or it is null.
*/
public static boolean isWeak(byte[] key, int offset) throws InvalidKeyException {
if (key == null) {
throw new InvalidKeyException("key == null");
}
if (key.length - offset < DES_KEY_LEN) {
throw new InvalidKeyException("key too short");
}
I:
for (int i=0; i<SEMIWEAKS.length; i++) {
for (int j=0; j<DES_KEY_LEN; j++) {
if (SEMIWEAKS[i][j] != key[offset+j]) {
continue I;
}
}
return true;
}
return false;
}
}