author | valeriep |
Tue, 08 May 2012 17:57:48 -0700 | |
changeset 12685 | 8a448b5b9006 |
parent 5506 | 202f599c92aa |
child 15010 | ec6b49ce42b1 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1997, 2009, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. Oracle designates this |
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* particular file as subject to the "Classpath" exception as provided |
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* by Oracle in the LICENSE file that accompanied this code. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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*/ |
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package com.sun.crypto.provider; |
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import java.security.SecureRandom; |
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import java.security.InvalidParameterException; |
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import java.security.InvalidAlgorithmParameterException; |
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import java.security.InvalidKeyException; |
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import java.security.spec.AlgorithmParameterSpec; |
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import javax.crypto.KeyGeneratorSpi; |
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import javax.crypto.SecretKey; |
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import javax.crypto.spec.DESKeySpec; |
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/** |
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* This class generates a DES key. |
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* |
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* @author Jan Luehe |
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* |
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*/ |
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public final class DESKeyGenerator extends KeyGeneratorSpi { |
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private SecureRandom random = null; |
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/** |
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* Empty constructor |
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*/ |
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public DESKeyGenerator() { |
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} |
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/** |
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* Initializes this key generator. |
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* |
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* @param random the source of randomness for this generator |
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*/ |
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protected void engineInit(SecureRandom random) { |
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this.random = random; |
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} |
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/** |
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* Initializes this key generator with the specified parameter |
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* set and a user-provided source of randomness. |
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* |
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* @param params the key generation parameters |
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* @param random the source of randomness for this key generator |
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* |
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* @exception InvalidAlgorithmParameterException if <code>params</code> is |
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* inappropriate for this key generator |
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*/ |
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protected void engineInit(AlgorithmParameterSpec params, |
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SecureRandom random) |
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throws InvalidAlgorithmParameterException { |
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throw new InvalidAlgorithmParameterException |
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("DES key generation does not take any parameters"); |
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} |
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/** |
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* Initializes this key generator for a certain keysize, using the given |
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* source of randomness. |
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* |
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* @param keysize the keysize. This is an algorithm-specific |
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* metric specified in number of bits. |
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* @param random the source of randomness for this key generator |
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*/ |
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protected void engineInit(int keysize, SecureRandom random) { |
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if (keysize != 56) { |
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throw new InvalidParameterException("Wrong keysize: must " |
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+ "be equal to 56"); |
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} |
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this.engineInit(random); |
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} |
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/** |
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* Generates the DES key. |
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* |
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* @return the new DES key |
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*/ |
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protected SecretKey engineGenerateKey() { |
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DESKey desKey = null; |
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if (this.random == null) { |
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this.random = SunJCE.RANDOM; |
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} |
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try { |
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byte[] key = new byte[DESKeySpec.DES_KEY_LEN]; |
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do { |
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this.random.nextBytes(key); |
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setParityBit(key, 0); |
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} while (DESKeySpec.isWeak(key, 0)); |
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desKey = new DESKey(key); |
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} catch (InvalidKeyException e) { |
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// this is never thrown |
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} |
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return desKey; |
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} |
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/* |
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* Does parity adjustment, using bit in position 8 as the parity bit, |
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* for 8 key bytes, starting at <code>offset</code>. |
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* |
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* The 8 parity bits of a DES key are only used for sanity-checking |
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* of the key, to see if the key could actually be a key. If you check |
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* the parity of the quantity, and it winds up not having the correct |
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* parity, then you'll know something went wrong. |
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* |
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* A key that is not parity adjusted (e.g. e4e4e4e4e4e4e4e4) produces the |
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* same output as a key that is parity adjusted (e.g. e5e5e5e5e5e5e5e5), |
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* because it is the 56 bits of the DES key that are cryptographically |
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* significant/"effective" -- the other 8 bits are just used for parity |
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* checking. |
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*/ |
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static void setParityBit(byte[] key, int offset) { |
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if (key == null) |
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return; |
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for (int i = 0; i < DESKeySpec.DES_KEY_LEN; i++) { |
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int b = key[offset] & 0xfe; |
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b |= (Integer.bitCount(b) & 1) ^ 1; |
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key[offset++] = (byte)b; |
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} |
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} |
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} |