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/* Copyright (C) 2022 Dinglan Peng
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This software 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 for more details.
*
* You should have received a copy of the GNU General Public License
* along with this software; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*/
package com.tigervnc.rdr;
import java.nio.ByteBuffer;
public class AESOutStream extends OutStream {
static final int maxMessageSize = 8192;
public AESOutStream(OutStream _out, byte[] key)
{
out = _out;
bufSize = maxMessageSize;
b = new byte[bufSize];
buffer = new byte[bufSize + 16 + 2];
ptr = offset = start = 0;
end = start + bufSize;
cipher = new AESEAXCipher(key);
counter = new byte[16];
}
public int length()
{
return offset + ptr - start;
}
public void flush()
{
int sentUpTo = start;
while (sentUpTo < ptr) {
int n = writeMessage(b, sentUpTo, ptr - sentUpTo);
sentUpTo += n;
offset += n;
}
ptr = start;
}
protected int overrun(int itemSize, int nItems)
{
if (itemSize > bufSize)
throw new Exception("AESOutStream overrun: max itemSize exceeded");
flush();
int nAvail;
nAvail = (end - ptr) / itemSize;
if (nAvail < nItems)
return nAvail;
return nItems;
}
protected int writeMessage(byte[] data, int dataPtr, int length)
{
if (length == 0)
return 0;
buffer[0] = (byte)((length & 0xff00) >> 8);
buffer[1] = (byte)(length & 0xff);
cipher.encrypt(data, dataPtr, length,
buffer, 0, 2,
counter,
buffer, 2,
buffer, 2 + length);
out.writeBytes(ByteBuffer.wrap(buffer, 0, length + 16 + 2),
length + 16 + 2);
out.flush();
// Update nonce by incrementing the counter as a
// 128bit little endian unsigned integer
for (int i = 0; i < 16; ++i) {
// increment until there is no carry
if (++counter[i] != 0) {
break;
}
}
return length;
}
private AESEAXCipher cipher;
private int start;
private int offset;
private int bufSize;
private byte[] buffer;
private byte[] counter;
private OutStream out;
}
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