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package org.bouncycastle.jcajce.io;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.security.GeneralSecurityException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import org.bouncycastle.crypto.io.InvalidCipherTextIOException;
/**
* A CipherOutputStream is composed of an OutputStream and a cipher so that write() methods process
* the written data with the cipher, and the output of the cipher is in turn written to the
* underlying OutputStream. The cipher must be fully initialized before being used by a
* CipherInputStream.
*
* For example, if the cipher is initialized for encryption, the CipherOutputStream will encrypt the
* data before writing the encrypted data to the underlying stream.
*
* This is a reimplementation of {@link javax.crypto.CipherOutputStream} that is safe for use with
* AEAD block ciphers, and does not silently catch {@link BadPaddingException} and
* {@link IllegalBlockSizeException} errors. Any errors that occur during {@link Cipher#doFinal()
* finalisation} are rethrown wrapped in an {@link InvalidCipherTextIOException}.
*
*/
public class CipherOutputStream
extends FilterOutputStream
{
private final Cipher cipher;
private final byte[] oneByte = new byte[1];
/**
* Constructs a CipherOutputStream from an OutputStream and a Cipher.
*/
public CipherOutputStream(OutputStream output, Cipher cipher)
{
super(output);
this.cipher = cipher;
}
/**
* Writes the specified byte to this output stream.
*
* @param b the byte.
* @throws java.io.IOException if an I/O error occurs.
*/
public void write(int b)
throws IOException
{
oneByte[0] = (byte)b;
write(oneByte, 0, 1);
}
/**
* Writes len bytes from the specified byte array starting at offset
* off to this output stream.
*
* @param b the data.
* @param off the start offset in the data.
* @param len the number of bytes to write.
* @throws java.io.IOException if an I/O error occurs.
*/
public void write(byte[] b, int off, int len)
throws IOException
{
byte[] outData = cipher.update(b, off, len);
if (outData != null)
{
out.write(outData);
}
}
/**
* Flushes this output stream by forcing any buffered output bytes that have already been
* processed by the encapsulated cipher object to be written out.
*
* 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 write methods is less than the cipher's block
* size, no bytes will be written out.
*
* @throws java.io.IOException if an I/O error occurs.
*/
public void flush()
throws IOException
{
out.flush();
}
/**
* Closes this output stream and releases any system resources associated with this stream.
*
* This method invokes the doFinal 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 flush method of this output stream.
*
* This method resets the encapsulated cipher object to its initial state and calls the
* close method of the underlying output stream.
*
* @throws java.io.IOException if an I/O error occurs.
* @throws InvalidCipherTextIOException if the data written to this stream was invalid
* ciphertext (e.g. the cipher is an AEAD cipher and the ciphertext tag check
* fails).
*/
public void close()
throws IOException
{
IOException error = null;
try
{
byte[] outData = cipher.doFinal();
if (outData != null)
{
out.write(outData);
}
}
catch (GeneralSecurityException e)
{
error = new InvalidCipherTextIOException("Error during cipher finalisation", e);
}
catch (Exception e)
{
error = new IOException("Error closing stream: " + e);
}
try
{
flush();
out.close();
}
catch (IOException e)
{
// Invalid ciphertext takes precedence over close error
if (error == null)
{
error = e;
}
}
if (error != null)
{
throw error;
}
}
}