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Diffstat (limited to 'libjava/classpath/gnu/javax/crypto/cipher/TripleDES.java')
| -rw-r--r-- | libjava/classpath/gnu/javax/crypto/cipher/TripleDES.java | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/javax/crypto/cipher/TripleDES.java b/libjava/classpath/gnu/javax/crypto/cipher/TripleDES.java new file mode 100644 index 00000000000..9b44c9ca7fb --- /dev/null +++ b/libjava/classpath/gnu/javax/crypto/cipher/TripleDES.java @@ -0,0 +1,196 @@ +/* TripleDES.java -- + Copyright (C) 2002, 2006 Free Software Foundation, Inc. + +This file is a part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or (at +your option) any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; if not, write to the Free Software +Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 +USA + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package gnu.javax.crypto.cipher; + +import gnu.java.security.Registry; + +import java.util.Collections; +import java.util.Iterator; +import java.security.InvalidKeyException; + +/** + * Triple-DES, 3DES, or DESede is a <i>combined cipher</i> that uses + * three iterations of the Data Encryption Standard cipher to improve + * the security (at the cost of speed) of plain DES. + * + * <p>Triple-DES runs the DES algorithm three times with three + * independent 56 bit keys. To encrypt:</p> + * + * <blockquote><i>C<sub>i</sub> = + * E<sub>k3</sub> ( E<sub>k2</sub><sup>-1</sup> ( E<sub>k1</sub> ( P<sub>i</sub> )))</i></blockquote> + * + * <p>And to decrypt:</p> + * + * <blockquote><i>P<sub>i</sub> = + * E<sub>k1</sub><sup>-1</sup> ( E<sub>k2</sub> ( E<sub>k3</sub><sup>-1</sup> ( C<sub>i</sub> )))</i></blockquote> + * + * <p>(The "ede" comes from the encryption operation, which runs + * Encrypt-Decrypt-Encrypt)</p> + * + * <p>References:</p> + * <ol> + * <li>Bruce Schneier, <i>Applied Cryptography: Protocols, Algorithms, + * and Source Code in C, Second Edition</i>. (1996 John Wiley and Sons) + * ISBN 0-471-11709-9. Page 294--295.</li> + * </ol> + */ +public class TripleDES extends BaseCipher +{ + + // Constants and variables. + // ----------------------------------------------------------------------- + + /** Triple-DES only operates on 64 bit blocks. */ + public static final int BLOCK_SIZE = 8; + + /** Triple-DES uses 168 bits of a parity-adjusted 192 bit key. */ + public static final int KEY_SIZE = 24; + + /** The underlying DES instance. */ + private DES des; + + // Constructors. + // ----------------------------------------------------------------------- + + /** + * Default 0-arguments constructor. + */ + public TripleDES() + { + super(Registry.TRIPLEDES_CIPHER, BLOCK_SIZE, KEY_SIZE); + des = new DES(); + } + + // Class methods. + // ----------------------------------------------------------------------- + + /** + * Transform a key so it will be parity adjusted. + * + * @param kb The key bytes to adjust. + * @param offset The starting offset into the key bytes. + * @see DES#adjustParity(byte[],int) + */ + public static void adjustParity(byte[] kb, int offset) + { + DES.adjustParity(kb, offset); + DES.adjustParity(kb, offset + 8); + DES.adjustParity(kb, offset + 16); + } + + /** + * Tests if a byte array has already been parity adjusted. + * + * @param kb The key bytes to test. + * @param offset The starting offset into the key bytes. + * @return <code>true</code> if the bytes in <i>kb</i> starting at + * <i>offset</i> are parity adjusted. + * @see DES#isParityAdjusted(byte[],int) + * @see #adjustParity(byte[],int) + */ + public static boolean isParityAdjusted(byte[] kb, int offset) + { + return DES.isParityAdjusted(kb, offset) + && DES.isParityAdjusted(kb, offset + 8) + && DES.isParityAdjusted(kb, offset + 16); + } + + // Methods implementing BaseCipher. + // ----------------------------------------------------------------------- + + public Object clone() + { + return new TripleDES(); + } + + public Iterator blockSizes() + { + return Collections.singleton(new Integer(BLOCK_SIZE)).iterator(); + } + + public Iterator keySizes() + { + return Collections.singleton(new Integer(KEY_SIZE)).iterator(); + } + + public Object makeKey(byte[] kb, int bs) throws InvalidKeyException + { + if (kb.length != KEY_SIZE) + throw new InvalidKeyException("TripleDES key must be 24 bytes"); + + if (!isParityAdjusted(kb, 0)) + adjustParity(kb, 0); + + byte[] k1 = new byte[DES.KEY_SIZE], k2 = new byte[DES.KEY_SIZE], k3 = new byte[DES.KEY_SIZE]; + System.arraycopy(kb, 0, k1, 0, DES.KEY_SIZE); + System.arraycopy(kb, DES.KEY_SIZE, k2, 0, DES.KEY_SIZE); + System.arraycopy(kb, 2 * DES.KEY_SIZE, k3, 0, DES.KEY_SIZE); + Context ctx = new Context(); + + ctx.k1 = (DES.Context) des.makeKey(k1, bs); + ctx.k2 = (DES.Context) des.makeKey(k2, bs); + ctx.k3 = (DES.Context) des.makeKey(k3, bs); + + return ctx; + } + + public void encrypt(byte[] in, int i, byte[] out, int o, Object K, int bs) + { + byte[] temp = new byte[BLOCK_SIZE]; + des.encrypt(in, i, temp, 0, ((Context) K).k1, bs); + des.decrypt(temp, 0, temp, 0, ((Context) K).k2, bs); + des.encrypt(temp, 0, out, o, ((Context) K).k3, bs); + } + + public void decrypt(byte[] in, int i, byte[] out, int o, Object K, int bs) + { + byte[] temp = new byte[BLOCK_SIZE]; + des.decrypt(in, i, temp, 0, ((Context) K).k3, bs); + des.encrypt(temp, 0, temp, 0, ((Context) K).k2, bs); + des.decrypt(temp, 0, out, o, ((Context) K).k1, bs); + } + + // Inner classes. + // ----------------------------------------------------------------------- + + private final class Context + { + DES.Context k1, k2, k3; + } +}
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