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diff --git a/libjava/classpath/gnu/javax/crypto/mode/IMode.java b/libjava/classpath/gnu/javax/crypto/mode/IMode.java
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+/* 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;
+
+/**
+ * <p>The basic visible methods of any block cipher mode.</p>
+ *
+ * <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>
+ *
+ * <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:</p>
+ *
+ * <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:</p>
+ *
+ * <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
+{
+
+  // Constants
+  // -------------------------------------------------------------------------
+
+  /**
+   * <p>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>.</p>
+   */
+  String STATE = "gnu.crypto.mode.state";
+
+  /**
+   * <p>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.</p>
+   */
+  String MODE_BLOCK_SIZE = "gnu.crypto.mode.block.size";
+
+  /**
+   * <p>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.</p>
+   */
+  String IV = "gnu.crypto.mode.iv";
+
+  /**
+   * <p>Constant indicating the instance is being used for <i>encryption</i>.</p>
+   */
+  int ENCRYPTION = 1;
+
+  /**
+   * <p>Constant indicating the instance is being used for <i>decryption</i>.</p>
+   */
+  int DECRYPTION = 2;
+
+  // Methods
+  // -------------------------------------------------------------------------
+
+  /**
+   * <p>A convenience method. Effectively invokes the <code>encryptBlock()</code>
+   * or <code>decryptBlock()</code> method depending on the operational state
+   * of the instance.</p>
+   *
+   * @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;
+}
+\ No newline at end of file