001/* DESedeKeySpec.java -- Keys for triple-DES. 002 Copyright (C) 2004 Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038 039package javax.crypto.spec; 040 041import java.security.InvalidKeyException; 042import java.security.spec.KeySpec; 043 044/** 045 * This class is a transparent wrapper for DES-EDE (Triple-DES) keys, 046 * which are arrays of 24 bytes. 047 * 048 * @author Casey Marshall (csm@gnu.org) 049 * @since 1.4 050 */ 051public class DESedeKeySpec implements KeySpec 052{ 053 054 // Constants. 055 // ------------------------------------------------------------------------ 056 057 /** 058 * The length of a triple-DES key, in bytes. 059 */ 060 public static final int DES_EDE_KEY_LEN = 24; 061 062 /** 063 * The key bytes. 064 */ 065 private byte[] key; 066 067 // Constructors. 068 // ------------------------------------------------------------------------ 069 070 /** 071 * Create a new DES-EDE key spec, copying the first 24 bytes from the 072 * byte array. 073 * 074 * @param key The key bytes. 075 * @throws java.security.InvalidKeyException If there are less than 24 076 * bytes in the array. 077 */ 078 public DESedeKeySpec(byte[] key) throws InvalidKeyException 079 { 080 this(key, 0); 081 } 082 083 /** 084 * Create a new DES-EDE key spec, starting at <code>offset</code> in 085 * the byte array. The first 24 bytes starting at <code>offset</code> 086 * are copied. 087 * 088 * @param key The key bytes. 089 * @param offset The offset into the byte array at which to begin. 090 * @throws java.security.InvalidKeyException If there are less than 24 091 * bytes starting at <code>offset</code>. 092 */ 093 public DESedeKeySpec(byte[] key, int offset) throws InvalidKeyException 094 { 095 if (key.length - offset < DES_EDE_KEY_LEN) 096 { 097 throw new InvalidKeyException("DES-EDE keys must be 24 bytes long"); 098 } 099 this.key = new byte[DES_EDE_KEY_LEN]; 100 System.arraycopy(key, offset, this.key, 0, DES_EDE_KEY_LEN); 101 } 102 103 // Class methods. 104 // ------------------------------------------------------------------------ 105 106 /** 107 * Returns whether or not the given key is <i>parity adjusted</i>; 108 * i.e. every byte in the key has an odd number of "1" bits. 109 * 110 * @param key The key bytes, considered between <code>[offset, 111 * offset+23]</code> 112 * @param offset The offset into the byte array at which to begin. 113 * @return True if all bytes have an odd number of "1" bits. 114 * @throws java.security.InvalidKeyException If there are not enough 115 * bytes in the array. 116 */ 117 public static boolean isParityAdjusted(byte[] key, int offset) 118 throws InvalidKeyException 119 { 120 if (key.length - offset < DES_EDE_KEY_LEN) 121 { 122 throw new InvalidKeyException("DES-EDE keys must be 24 bytes long"); 123 } 124 boolean parity = false; 125 boolean oddbits = false; 126 for (int i = 0; i < DES_EDE_KEY_LEN; i++) 127 { 128 oddbits = false; 129 for (int j = 0; j < 8; j++) 130 { 131 oddbits ^= (key[i+offset] & 1 << j) != 0; 132 } 133 parity &= oddbits; 134 } 135 return parity; 136 } 137 138 // Instance methods. 139 // ------------------------------------------------------------------------ 140 141 /** 142 * Return the key as a byte array. This method does not copy the byte 143 * array. 144 * 145 * @return The key bytes. 146 */ 147 public byte[] getKey() 148 { 149 return key; 150 } 151}