/*
* 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 triple-DES (DES-EDE) key.
*/
public class DESedeKeySpec implements KeySpec {
/**
* The length of a DES-EDE key in bytes.
*/
public static final int DES_EDE_KEY_LEN = 24;
private final byte[] key;
/**
* Creates a new <code>DESedeKeySpec</code> instance from the first 24 (
* {@link #DES_EDE_KEY_LEN}) bytes of the specified key data.
*
* @param key
* the key data.
* @throws InvalidKeyException
* if the length of the key data is less than 24.
* @throws NullPointerException
* if the key data is null.
*/
public DESedeKeySpec(byte[] key) throws InvalidKeyException {
if (key == null) {
throw new NullPointerException("key == null");
}
if (key.length < DES_EDE_KEY_LEN) {
throw new InvalidKeyException();
}
this.key = new byte[DES_EDE_KEY_LEN];
System.arraycopy(key, 0, this.key, 0, DES_EDE_KEY_LEN);
}
/**
* Creates a new <code>DESedeKeySpec</code> instance from the first 24 (
* {@link #DES_EDE_KEY_LEN} ) 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 key data starting at offset is less than
* 24.
* @throws NullPointerException
* if the key data is null.
*/
public DESedeKeySpec(byte[] key, int offset) throws InvalidKeyException {
if (key == null) {
throw new NullPointerException("key == null");
}
if (key.length - offset < DES_EDE_KEY_LEN) {
throw new InvalidKeyException();
}
this.key = new byte[DES_EDE_KEY_LEN];
System.arraycopy(key, offset, this.key, 0, DES_EDE_KEY_LEN);
}
/**
* Returns a copy of the key.
*
* @return a copy of the key.
*/
public byte[] getKey() {
byte[] result = new byte [DES_EDE_KEY_LEN];
System.arraycopy(this.key, 0, result, 0, DES_EDE_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
* 24.
*/
public static boolean isParityAdjusted(byte[] key, int offset) throws InvalidKeyException {
if (key.length - offset < DES_EDE_KEY_LEN) {
throw new InvalidKeyException();
}
for (int i=offset; i<DES_EDE_KEY_LEN+offset; i++) {
int b = key[i];
if ((((b & 1) + ((b & 2) >> 1) + ((b & 4) >> 2)
+ ((b & 8) >> 3) + ((b & 16) >> 4) + ((b & 32) >> 5)
+ ((b & 64) >> 6)) & 1) == ((b & 128) >> 7)) {
return false;
}
}
return true;
}
}