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/* * Copyright (c) 1997, 2007, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.crypto; import java.io.*; /** * A CipherOutputStream is composed of an OutputStream and a Cipher so * that write() methods first process the data before writing them out * to the underlying OutputStream.  The cipher must be fully * initialized before being used by a CipherOutputStream. * * <p> For example, if the cipher is initialized for encryption, the * CipherOutputStream will attempt to encrypt data before writing out the * encrypted data. * * <p> This class adheres strictly to the semantics, especially the * failure semantics, of its ancestor classes * java.io.OutputStream and java.io.FilterOutputStream.  This class * has exactly those methods specified in its ancestor classes, and * overrides them all.  Moreover, this class catches all exceptions * that are not thrown by its ancestor classes. * * <p> It is crucial for a programmer using this class not to use * methods that are not defined or overriden in this class (such as a * new method or constructor that is later added to one of the super * classes), because the design and implementation of those methods * are unlikely to have considered security impact with regard to * CipherOutputStream. * * @author  Li Gong * @see     java.io.OutputStream * @see     java.io.FilterOutputStream * @see     javax.crypto.Cipher * @see     javax.crypto.CipherInputStream * * @since 1.4 */ public class CipherOutputStream extends FilterOutputStream {     // the cipher engine to use to process stream data    private Cipher cipher;     // the underlying output stream    private OutputStream output;     /* the buffer holding one byte of incoming data */    private byte[] ibuffer = new byte[1];     // the buffer holding data ready to be written out    private byte[] obuffer;     /**     *     * Constructs a CipherOutputStream from an OutputStream and a     * Cipher.     * <br>Note: if the specified output stream or cipher is     * null, a NullPointerException may be thrown later when     * they are used.     *     * @param os  the OutputStream object     * @param c   an initialized Cipher object     */    public CipherOutputStream(OutputStream os, Cipher c) {        super(os);        output = os;        cipher = c;    };     /**     * Constructs a CipherOutputStream from an OutputStream without     * specifying a Cipher. This has the effect of constructing a     * CipherOutputStream using a NullCipher.     * <br>Note: if the specified output stream is null, a     * NullPointerException may be thrown later when it is used.     *     * @param os  the OutputStream object     */    protected CipherOutputStream(OutputStream os) {        super(os);        output = os;        cipher = new NullCipher();    }     /**     * Writes the specified byte to this output stream.     *     * @param      b   the <code>byte</code>.     * @exception  IOException  if an I/O error occurs.     * @since      JCE1.2     */    public void write(int b) throws IOException {        ibuffer[0] = (byte) b;        obuffer = cipher.update(ibuffer, 0, 1);        if (obuffer != null) {            output.write(obuffer);            obuffer = null;        }    };     /**     * Writes <code>b.length</code> bytes from the specified byte array     * to this output stream.     * <p>     * The <code>write</code> method of     * <code>CipherOutputStream</code> calls the <code>write</code>     * method of three arguments with the three arguments     * <code>b</code>, <code>0</code>, and <code>b.length</code>.     *     * @param      b   the data.     * @exception  NullPointerException if <code>b</code> is null.     * @exception  IOException  if an I/O error occurs.     * @see        javax.crypto.CipherOutputStream#write(byte[], int, int)     * @since JCE1.2     */    public void write(byte b[]) throws IOException {        write(b, 0, b.length);    }     /**     * Writes <code>len</code> bytes from the specified byte array     * starting at offset <code>off</code> to this output stream.     *     * @param      b     the data.     * @param      off   the start offset in the data.     * @param      len   the number of bytes to write.     * @exception  IOException  if an I/O error occurs.     * @since      JCE1.2     */    public void write(byte b[], int off, int len) throws IOException {        obuffer = cipher.update(b, off, len);        if (obuffer != null) {            output.write(obuffer);            obuffer = null;        }    }     /**     * Flushes this output stream by forcing any buffered output bytes     * that have already been processed by the encapsulated cipher object     * to be written out.     *     * <p>Any bytes buffered by the encapsulated cipher     * and waiting to be processed by it will not be written out. For example,     * if the encapsulated cipher is a block cipher, and the total number of     * bytes written using one of the <code>write</code> methods is less than     * the cipher's block size, no bytes will be written out.     *     * @exception  IOException  if an I/O error occurs.     * @since      JCE1.2     */    public void flush() throws IOException {        if (obuffer != null) {            output.write(obuffer);            obuffer = null;        }        output.flush();    }     /**     * Closes this output stream and releases any system resources     * associated with this stream.     * <p>     * This method invokes the <code>doFinal</code> method of the encapsulated     * cipher object, which causes any bytes buffered by the encapsulated     * cipher to be processed. The result is written out by calling the     * <code>flush</code> method of this output stream.     * <p>     * This method resets the encapsulated cipher object to its initial state     * and calls the <code>close</code> method of the underlying output     * stream.     *     * @exception  IOException  if an I/O error occurs.     * @since      JCE1.2     */    public void close() throws IOException {        try {            obuffer = cipher.doFinal();        } catch (IllegalBlockSizeException e) {            obuffer = null;        } catch (BadPaddingException e) {            obuffer = null;        }        try {            flush();        } catch (IOException ignored) {}        out.close();    }}