/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @author Alexander Y. Kleymenov
* @version $Revision$
*/
package javax.crypto;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import javax.crypto.NullCipher;
/**
* This class wraps an output stream and a cipher so that {@code write} methods
* send the data through the cipher before writing them to the underlying output
* stream.
* <p>
* The cipher must be initialized for the requested operation before being used
* by a {@code CipherOutputStream}. For example, if a cipher initialized for
* encryption is used with a {@code CipherOutputStream}, the {@code
* CipherOutputStream} tries to encrypt the data writing it out.
*/
public class CipherOutputStream extends FilterOutputStream {
private final Cipher cipher;
private final byte[] arr = new byte[1];
/**
* Creates a new {@code CipherOutputStream} instance for an {@code
* OutputStream} and a {@code Cipher}.
*
* @param os
* the output stream to write data to.
* @param c
* the cipher to process the data with.
*/
public CipherOutputStream(OutputStream os, Cipher c) {
super(os);
cipher = c;
}
/**
* Creates a new {@code CipherOutputStream} instance for an {@code
* OutputStream} without a cipher.
* <p>
* A {@code NullCipher} is created to process the data.
*
* @param os
* the output stream to write the data to.
*/
protected CipherOutputStream(OutputStream os) {
this(os, new NullCipher());
}
/**
* Writes the single byte to this cipher output stream.
*
* @param b
* the byte to write.
* @throws IOException
* if an error occurs.
*/
@Override
public void write(int b) throws IOException {
byte[] result;
arr[0] = (byte) b;
result = cipher.update(arr);
if (result != null) {
out.write(result);
}
}
/**
* Writes the buffer of bytes to this cipher output stream.
*
* @param b
* the buffer of bytes.
* @throws IOException
* if an error occurs.
*/
@Override
public void write(byte[] b) throws IOException {
write(b, 0, b.length);
}
/**
* Writes the {@code len} bytes from buffer {@code b} starting at offset
* {@code off} to this cipher output stream.
*
* @param b
* the buffer.
* @param off
* the offset to start at.
* @param len
* the number of bytes.
* @throws IOException
* if an error occurs.
*/
@Override
public void write(byte[] b, int off, int len) throws IOException {
if (len == 0) {
return;
}
byte[] result = cipher.update(b, off, len);
if (result != null) {
out.write(result);
}
}
/**
* Flushes this cipher output stream.
*
* @throws IOException
* if an error occurs
*/
@Override
public void flush() throws IOException {
out.flush();
}
/**
* Close this cipher output stream.
* <p>
* On the underlying cipher {@code doFinal} will be invoked, and any
* buffered bytes from the cipher are also written out, and the cipher is
* reset to its initial state. The underlying output stream is also closed.
*
* @throws IOException
* if an error occurs.
*/
@Override
public void close() throws IOException {
byte[] result;
try {
if (cipher != null) {
result = cipher.doFinal();
if (result != null) {
out.write(result);
}
}
if (out != null) {
out.flush();
}
} catch (BadPaddingException e) {
throw new IOException(e.getMessage());
} catch (IllegalBlockSizeException e) {
throw new IOException(e.getMessage());
} finally {
if (out != null) {
out.close();
}
}
}
}