| /* IMode.java -- |
| Copyright (C) 2001, 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.mode; |
| |
| import gnu.javax.crypto.cipher.IBlockCipher; |
| |
| /** |
| * The basic visible methods of any block cipher mode. |
| * <p> |
| * Block ciphers encrypt plaintext in fixed size n-bit blocks. For messages |
| * larger than n bits, the simplest approach is to segment the message into |
| * n-bit blocks and process (encrypt and/or decrypt) each one separately |
| * (Electronic Codebook or ECB mode). But this approach has disadvantages in |
| * most applications. The block cipher modes of operations are one way of |
| * working around those disadvantages. |
| * <p> |
| * A <i>Mode</i> always employs an underlying block cipher for processing its |
| * input. For all intents and purposes, a <i>Mode</i> appears to behave as any |
| * other block cipher with the following differences: |
| * <ul> |
| * <li>Depending on the specifications of the mode, the block size may be |
| * different that that of the underlying cipher.</li> |
| * <li>While some modes of operations allow operations on block sizes that can |
| * be 1-bit long, this library will only deal with sizes that are multiple of 8 |
| * bits. This is because the <tt>byte</tt> is the smallest, easy to handle, |
| * primitive type in Java.</li> |
| * <li>Some modes need an <i>Initialisation Vector</i> (IV) to be properly |
| * initialised.</li> |
| * </ul> |
| * <p> |
| * Possible additional initialisation values for an instance of that type are: |
| * <ul> |
| * <li>The block size in which to operate this mode instance. This value is |
| * <b>optional</b>, if unspecified, the underlying block cipher's configured |
| * block size shall be used.</li> |
| * <li>Whether this mode will be used for encryption or decryption. This value |
| * is <b>mandatory</b> and should be included in the initialisation parameters. |
| * If it isn't, a {@link java.lang.IllegalStateException} will be thrown if any |
| * method, other than <code>reset()</code> is invoked on the instance.</li> |
| * <li>The byte array containing the <i>initialisation vector</i>, if required |
| * by this type of mode.</li> |
| * </ul> |
| */ |
| public interface IMode |
| extends IBlockCipher |
| { |
| /** |
| * Property name of the state in which to operate this mode. The value |
| * associated to this property name is taken to be an {@link Integer} which |
| * value is either <code>ENCRYPTION</code> or <code>DECRYPTION</code>. |
| */ |
| String STATE = "gnu.crypto.mode.state"; |
| /** |
| * Property name of the block size in which to operate this mode. The value |
| * associated with this property name is taken to be an {@link Integer}. If |
| * it is not specified, the value of the block size of the underlying block |
| * cipher, used to construct the mode instance, shall be used. |
| */ |
| String MODE_BLOCK_SIZE = "gnu.crypto.mode.block.size"; |
| /** |
| * Property name of the initialisation vector to use, if required, with this |
| * instance. The value associated with this property name is taken to be a |
| * byte array. If the concrete instance needs such a parameter, and it has not |
| * been specified as part of the initialissation parameters, an all-zero byte |
| * array of the appropriate size shall be used. |
| */ |
| String IV = "gnu.crypto.mode.iv"; |
| /** Constant indicating the instance is being used for <i>encryption</i>. */ |
| int ENCRYPTION = 1; |
| /** Constant indicating the instance is being used for <i>decryption</i>. */ |
| int DECRYPTION = 2; |
| |
| /** |
| * A convenience method. Effectively invokes the <code>encryptBlock()</code> |
| * or <code>decryptBlock()</code> method depending on the operational state |
| * of the instance. |
| * |
| * @param in the plaintext. |
| * @param inOffset index of <code>in</code> from which to start considering |
| * data. |
| * @param out the ciphertext. |
| * @param outOffset index of <code>out</code> from which to store result. |
| * @exception IllegalStateException if the instance is not initialised. |
| */ |
| void update(byte[] in, int inOffset, byte[] out, int outOffset) |
| throws IllegalStateException; |
| } |