001/* CipherOutputStream.java -- Filters output through a cipher.
002   Copyright (C) 2004  Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038
039package javax.crypto;
040
041import java.io.FilterOutputStream;
042import java.io.IOException;
043import java.io.OutputStream;
044
045/**
046 * A filtered output stream that transforms data written to it with a
047 * {@link Cipher} before sending it to the underlying output stream.
048 *
049 * @author Casey Marshall (csm@gnu.org)
050 */
051public class CipherOutputStream extends FilterOutputStream
052{
053  /** The underlying cipher. */
054  private Cipher cipher;
055
056  /**
057   * Create a new cipher output stream. The cipher argument must have already
058   * been initialized.
059   *
060   * @param out The sink for transformed data.
061   * @param cipher The cipher to transform data with.
062   */
063  public CipherOutputStream(OutputStream out, Cipher cipher)
064  {
065    super(out);
066    this.cipher = (cipher != null) ? cipher : new NullCipher();
067  }
068
069  /**
070   * Create a cipher output stream with no cipher.
071   *
072   * @param out The sink for transformed data.
073   */
074  protected CipherOutputStream(OutputStream out)
075  {
076    super(out);
077  }
078
079  /**
080   * Close this output stream, and the sink output stream.
081   * <p>
082   * This method will first invoke the {@link Cipher#doFinal()} method of the
083   * underlying {@link Cipher}, and writes the output of that method to the
084   * sink output stream.
085   *
086   * @throws IOException If an I/O error occurs, or if an error is caused by
087   *           finalizing the transformation.
088   */
089  public void close() throws IOException
090  {
091    try
092      {
093        out.write(cipher.doFinal());
094        out.flush();
095        out.close();
096      }
097    catch (Exception cause)
098      {
099        IOException ioex = new IOException(String.valueOf(cause));
100        ioex.initCause(cause);
101        throw ioex;
102      }
103  }
104
105  /**
106   * Flush any pending output.
107   *
108   * @throws IOException If an I/O error occurs.
109   */
110  public void flush() throws IOException
111  {
112    out.flush();
113  }
114
115  /**
116   * Write a single byte to the output stream.
117   *
118   * @param b The next byte.
119   * @throws IOException If an I/O error occurs, or if the underlying cipher is
120   *           not in the correct state to transform data.
121   */
122  public void write(int b) throws IOException
123  {
124    write(new byte[] { (byte) b }, 0, 1);
125  }
126
127  /**
128   * Write a byte array to the output stream.
129   *
130   * @param buf The next bytes.
131   * @throws IOException If an I/O error occurs, or if the underlying cipher is
132   *           not in the correct state to transform data.
133   */
134  public void write(byte[] buf) throws IOException
135  {
136    write(buf, 0, buf.length);
137  }
138
139  /**
140   * Write a portion of a byte array to the output stream.
141   *
142   * @param buf The next bytes.
143   * @param off The offset in the byte array to start.
144   * @param len The number of bytes to write.
145   * @throws IOException If an I/O error occurs, or if the underlying cipher is
146   *           not in the correct state to transform data.
147   */
148  public void write(byte[] buf, int off, int len) throws IOException
149  {
150    byte[] b = cipher.update(buf, off, len);
151    if (b != null)
152      out.write(b);
153  }
154}