1 /* TripleDES.java -- 2 Copyright (C) 2002, 2006 Free Software Foundation, Inc. 3 4 This file is a part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2 of the License, or (at 9 your option) any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; if not, write to the Free Software 18 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 19 USA 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package gnu.javax.crypto.cipher; 40 41 import gnu.java.security.Registry; 42 43 import java.util.ArrayList; 44 import java.util.Collections; 45 import java.util.Iterator; 46 import java.security.InvalidKeyException; 47 48 /** 49 * Triple-DES, 3DES, or DESede is a <i>combined cipher</i> that uses three 50 * iterations of the Data Encryption Standard cipher to theoretically improve 51 * the security of plain DES, at the cost of speed. 52 * <p> 53 * Triple-DES runs the DES algorithm three times with one, two or three 54 * independent 56-bit (DES) keys. When used with one DES key, the cipher behaves 55 * exactly like a (slower) DES. 56 * <p> 57 * To encrypt: 58 * <blockquote><i>C<sub>i</sub> = E<sub>k3</sub> ( E<sub>k2</sub><sup>-1</sup> ( 59 * E<sub>k1</sub> ( P<sub>i</sub> )))</i> 60 * </blockquote> 61 * <p> 62 * And to decrypt: 63 * <blockquote><i>P<sub>i</sub> = E<sub>k1</sub><sup>-1</sup> ( 64 * E<sub>k2</sub> ( E<sub>k3</sub><sup>-1</sup> ( C<sub>i</sub> )))</i> 65 * </blockquote> 66 * <p> 67 * (The "ede" comes from the encryption operation, which runs 68 * Encrypt-Decrypt-Encrypt) 69 * <p> 70 * References: 71 * <ol> 72 * <li>Bruce Schneier, <i>Applied Cryptography: Protocols, Algorithms, and 73 * Source Code in C, Second Edition</i>. (1996 John Wiley and Sons) ISBN 74 * 0-471-11709-9. Page 294--295.</li> 75 * </ol> 76 */ 77 public class TripleDES 78 extends BaseCipher 79 { 80 /** Triple-DES only operates on 64 bit blocks. */ 81 public static final int BLOCK_SIZE = 8; 82 /** By default, Triple-DES uses 168 bits of a parity-adjusted 192 bit key. */ 83 public static final int KEY_SIZE = 24; 84 /** The underlying DES instance. */ 85 private DES des; 86 87 /** 88 * Default 0-arguments constructor. 89 */ TripleDES()90 public TripleDES() 91 { 92 super(Registry.TRIPLEDES_CIPHER, BLOCK_SIZE, KEY_SIZE); 93 des = new DES(); 94 } 95 96 /** 97 * Convenience method which calls the method with same name and three 98 * arguments, passing <code>3</code> as the value of the first parameter. 99 * 100 * @param kb The key bytes to adjust. 101 * @param offset The starting offset into the key bytes. 102 */ adjustParity(byte[] kb, int offset)103 public static void adjustParity(byte[] kb, int offset) 104 { 105 adjustParity(3, kb, offset); 106 } 107 108 /** 109 * Adjusts, in-situ, the parity of the designated bytes, so they can be used 110 * as DES keys for a 3-DES 1-, 2- or 3-key cipher. 111 * 112 * @param keyCount the number of independent DES keys. Can be either 113 * <code>1</code>, <code>2</code> or <code>3</code>. Any other value 114 * will cause an {@link IllegalArgumentException} to be raised. 115 * @param kb the array containing the key bytes to adjust. MUST have at least 116 * <code>8 * keyCount</code> bytes starting at offset position 117 * <code>offset</code>, otherwise an 118 * {@link ArrayIndexOutOfBoundsException} will be raised. 119 * @param offset the starting offset into the array. 120 * @see DES#adjustParity(byte[],int) 121 */ adjustParity(int keyCount, byte[] kb, int offset)122 public static void adjustParity(int keyCount, byte[] kb, int offset) 123 { 124 if (keyCount < 1 || keyCount > 3) 125 throw new IllegalArgumentException("Invalid keyCount value: " + keyCount); 126 DES.adjustParity(kb, offset); 127 if (keyCount > 1) 128 DES.adjustParity(kb, offset + 8); 129 if (keyCount > 2) 130 DES.adjustParity(kb, offset + 16); 131 } 132 133 /** 134 * Convenience method which calls the method with same name and three 135 * arguments, passing <code>3</code> as the value of the first parameter. 136 * 137 * @param kb The key bytes to test. 138 * @param offset The starting offset into the key bytes. 139 * @return <code>true</code> if the bytes in <i>kb</i> starting at 140 * <i>offset</i> are parity adjusted. 141 * @see DES#isParityAdjusted(byte[],int) 142 * @see #adjustParity(byte[],int) 143 */ isParityAdjusted(byte[] kb, int offset)144 public static boolean isParityAdjusted(byte[] kb, int offset) 145 { 146 return isParityAdjusted(3, kb, offset); 147 } 148 149 /** 150 * Tests if enough bytes, expected to be used as DES keys for a 3-DES 1-, 2- 151 * or 3-key cipher, located in a designated byte array, has already been 152 * parity adjusted. 153 * 154 * @param keyCount the number of independent DES keys. Can be either 155 * <code>1</code>, <code>2</code> or <code>3</code>. Any other value 156 * will cause an {@link IllegalArgumentException} to be raised. 157 * @param kb the array containing the key bytes to test. MUST have at least 158 * <code>8 * keyCount</code> bytes starting at offset position 159 * <code>offset</code>, otherwise an 160 * {@link ArrayIndexOutOfBoundsException} will be raised. 161 * @param offset the starting offset into the array. 162 * @return <code>true</code> if the bytes in <i>kb</i> starting at 163 * <i>offset</i> are parity adjusted. 164 * @see DES#isParityAdjusted(byte[],int) 165 * @see #adjustParity(int,byte[],int) 166 */ isParityAdjusted(int keyCount, byte[] kb, int offset)167 public static boolean isParityAdjusted(int keyCount, byte[] kb, int offset) 168 { 169 if (keyCount < 1 || keyCount > 3) 170 throw new IllegalArgumentException("Invalid keyCount value: " + keyCount); 171 boolean result = DES.isParityAdjusted(kb, offset); 172 if (keyCount > 1) 173 result = result && DES.isParityAdjusted(kb, offset + 8); 174 if (keyCount > 2) 175 result = result && DES.isParityAdjusted(kb, offset + 16); 176 return result; 177 } 178 clone()179 public Object clone() 180 { 181 return new TripleDES(); 182 } 183 blockSizes()184 public Iterator blockSizes() 185 { 186 return Collections.singleton(Integer.valueOf(BLOCK_SIZE)).iterator(); 187 } 188 keySizes()189 public Iterator keySizes() 190 { 191 ArrayList al = new ArrayList(); 192 al.add(Integer.valueOf(8)); 193 al.add(Integer.valueOf(16)); 194 al.add(Integer.valueOf(24)); 195 return Collections.unmodifiableList(al).iterator(); 196 } 197 makeKey(byte[] kb, int bs)198 public Object makeKey(byte[] kb, int bs) throws InvalidKeyException 199 { 200 if (kb.length != 8 && kb.length != 16 && kb.length != 24) 201 throw new InvalidKeyException("TripleDES key must be 8, 16 or 24 bytes: " 202 + kb.length); 203 Context ctx = new Context(); 204 byte[] k1 = new byte[DES.KEY_SIZE]; 205 System.arraycopy(kb, 0, k1, 0, DES.KEY_SIZE); 206 if (! DES.isParityAdjusted(k1, 0)) 207 DES.adjustParity(k1, 0); 208 ctx.k1 = (DES.Context) des.makeKey(k1, bs); 209 210 if (kb.length == 8) 211 { 212 ctx.k2 = (DES.Context) des.makeKey(k1, bs); 213 ctx.k3 = (DES.Context) des.makeKey(k1, bs); 214 } 215 else 216 { 217 byte[] k2 = new byte[DES.KEY_SIZE]; 218 System.arraycopy(kb, DES.KEY_SIZE, k2, 0, DES.KEY_SIZE); 219 if (! DES.isParityAdjusted(k2, 0)) 220 DES.adjustParity(k2, 0); 221 ctx.k2 = (DES.Context) des.makeKey(k2, bs); 222 223 byte[] k3 = new byte[DES.KEY_SIZE]; 224 if (kb.length == 16) 225 ctx.k3 = (DES.Context) des.makeKey(k1, bs); 226 else 227 { 228 System.arraycopy(kb, 2 * DES.KEY_SIZE, k3, 0, DES.KEY_SIZE); 229 if (! DES.isParityAdjusted(k3, 0)) 230 DES.adjustParity(k3, 0); 231 ctx.k3 = (DES.Context) des.makeKey(k3, bs); 232 } 233 } 234 return ctx; 235 } 236 encrypt(byte[] in, int i, byte[] out, int o, Object K, int bs)237 public void encrypt(byte[] in, int i, byte[] out, int o, Object K, int bs) 238 { 239 byte[] temp = new byte[BLOCK_SIZE]; 240 des.encrypt(in, i, temp, 0, ((Context) K).k1, bs); 241 des.decrypt(temp, 0, temp, 0, ((Context) K).k2, bs); 242 des.encrypt(temp, 0, out, o, ((Context) K).k3, bs); 243 } 244 decrypt(byte[] in, int i, byte[] out, int o, Object K, int bs)245 public void decrypt(byte[] in, int i, byte[] out, int o, Object K, int bs) 246 { 247 byte[] temp = new byte[BLOCK_SIZE]; 248 des.decrypt(in, i, temp, 0, ((Context) K).k3, bs); 249 des.encrypt(temp, 0, temp, 0, ((Context) K).k2, bs); 250 des.decrypt(temp, 0, out, o, ((Context) K).k1, bs); 251 } 252 253 private final class Context 254 { 255 DES.Context k1, k2, k3; 256 } 257 } 258