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jeremybenn |
/* CipherOutputStream.java -- Filters output through a cipher.
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Copyright (C) 2004 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package javax.crypto;
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import java.io.FilterOutputStream;
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import java.io.IOException;
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import java.io.OutputStream;
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/**
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* A filtered output stream that transforms data written to it with a
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* {@link Cipher} before sending it to the underlying output stream.
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*
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* @author Casey Marshall (csm@gnu.org)
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*/
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public class CipherOutputStream extends FilterOutputStream
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{
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/** The underlying cipher. */
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private Cipher cipher;
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/**
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* Create a new cipher output stream. The cipher argument must have already
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* been initialized.
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*
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* @param out The sink for transformed data.
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* @param cipher The cipher to transform data with.
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*/
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public CipherOutputStream(OutputStream out, Cipher cipher)
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{
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super(out);
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this.cipher = (cipher != null) ? cipher : new NullCipher();
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}
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/**
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* Create a cipher output stream with no cipher.
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*
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* @param out The sink for transformed data.
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*/
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protected CipherOutputStream(OutputStream out)
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{
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super(out);
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}
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/**
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* Close this output stream, and the sink output stream.
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* <p>
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* This method will first invoke the {@link Cipher#doFinal()} method of the
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* underlying {@link Cipher}, and writes the output of that method to the
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* sink output stream.
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*
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* @throws IOException If an I/O error occurs, or if an error is caused by
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* finalizing the transformation.
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*/
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public void close() throws IOException
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{
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try
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{
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out.write(cipher.doFinal());
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out.flush();
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out.close();
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}
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catch (Exception cause)
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{
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IOException ioex = new IOException(String.valueOf(cause));
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ioex.initCause(cause);
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throw ioex;
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}
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}
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/**
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* Flush any pending output.
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*
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* @throws IOException If an I/O error occurs.
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*/
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public void flush() throws IOException
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{
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out.flush();
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}
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/**
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* Write a single byte to the output stream.
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*
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* @param b The next byte.
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* @throws IOException If an I/O error occurs, or if the underlying cipher is
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* not in the correct state to transform data.
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*/
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public void write(int b) throws IOException
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{
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write(new byte[] { (byte) b }, 0, 1);
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}
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/**
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* Write a byte array to the output stream.
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*
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* @param buf The next bytes.
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* @throws IOException If an I/O error occurs, or if the underlying cipher is
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* not in the correct state to transform data.
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*/
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public void write(byte[] buf) throws IOException
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{
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write(buf, 0, buf.length);
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}
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/**
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* Write a portion of a byte array to the output stream.
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*
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* @param buf The next bytes.
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* @param off The offset in the byte array to start.
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* @param len The number of bytes to write.
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* @throws IOException If an I/O error occurs, or if the underlying cipher is
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* not in the correct state to transform data.
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*/
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public void write(byte[] buf, int off, int len) throws IOException
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{
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byte[] b = cipher.update(buf, off, len);
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if (b != null)
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out.write(b);
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}
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}
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