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/*
* Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
import javax.crypto.Cipher;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.ByteBuffer;
/*
* @test
* @summary This tests overlapping buffers using ByteBuffer.slice() with
* array-backed ByteBuffer, read only array-backed, ByteBuffer, and direct
* ByteBuffer.
*/
/*
* This tests overlapping buffers created with ByteBuffer.slice(). That is
* when the input and output ByteBuffers have shared memory (use the same
* underlying buffer space, commonly used for in-place crypto). The
* complication is the Cipher object specifies that it must be copy-safe. That
* means the output buffer will not overwrite any input data that has not been
* processed. If the output buffer's position or offset is greater than the
* input's overwriting will occur.
*/
public class OverlapByteBuffer {
public static void main(String[] args) throws Exception {
byte[] baseBuf = new byte[8192];
ByteBuffer output, input, in;
// Output offset from the baseBuf
int outOfs;
for (int i = 0; i < 3; i++) {
for (outOfs = -1; outOfs <= 1; outOfs++) {
SecretKeySpec key = new SecretKeySpec(new byte[16], "AES");
GCMParameterSpec params =
new GCMParameterSpec(128, new byte[12]);
Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, key, params);
// Offset on the particular ByteBuffer (aka position())
int inOfsInBuf = 1;
int outOfsInBuf = inOfsInBuf + outOfs;
int sliceLen = cipher.getOutputSize(baseBuf.length);
int bufferSize = sliceLen + Math.max(inOfsInBuf, outOfsInBuf);
byte[] buffer;
// Create overlapping input and output buffers
switch (i) {
case 0 -> {
buffer = new byte[bufferSize];
output = ByteBuffer.wrap(buffer, outOfsInBuf, sliceLen).
slice();
input = ByteBuffer.wrap(buffer, inOfsInBuf, sliceLen).
slice();
System.out.println("Using array-backed ByteBuffer");
in = input.duplicate();
}
case 1 -> {
buffer = new byte[bufferSize];
output = ByteBuffer.wrap(buffer, outOfsInBuf, sliceLen).
slice();
input = ByteBuffer.wrap(buffer, inOfsInBuf, sliceLen).
slice();
System.out.println("Using read-only array-backed " + "ByteBuffer");
in = input.asReadOnlyBuffer();
}
case 2 -> {
System.out.println("Using direct ByteBuffer");
ByteBuffer buf = ByteBuffer.allocateDirect(bufferSize);
output = buf.duplicate();
output.position(outOfsInBuf);
output.limit(sliceLen + outOfsInBuf);
output = output.slice();
input = buf.duplicate();
input.position(inOfsInBuf);
input.limit(sliceLen + inOfsInBuf);
input = input.slice();
in = input.duplicate();
}
default -> {
throw new Exception("Unknown index " + i);
}
}
System.out.println("inOfsInBuf = " + inOfsInBuf);
System.out.println("outOfsInBuf = " + outOfsInBuf);
// Copy data into shared buffer
input.put(baseBuf);
input.flip();
in.limit(input.limit());
try {
int ctSize = cipher.doFinal(in, output);
// Get ready to decrypt
byte[] tmp = new byte[ctSize];
output.flip();
output.get(tmp);
output.clear();
input.clear();
input.put(tmp);
input.flip();
in.clear();
in.limit(input.limit());
cipher.init(Cipher.DECRYPT_MODE, key, params);
cipher.doFinal(in, output);
output.flip();
ByteBuffer b = ByteBuffer.wrap(baseBuf);
if (b.compareTo(output) != 0) {
System.err.println(
"\nresult (" + output + "):\n" +
byteToHex(output) +
"\nexpected (" + b + "):\n" +
byteToHex(b));
throw new Exception("Mismatch");
}
} catch (Exception e) {
throw new Exception("Error with base offset " + outOfs, e);
}
}
}
}
private static String byteToHex(ByteBuffer bb) {
StringBuilder s = new StringBuilder();
while (bb.remaining() > 0) {
s.append(String.format("%02x", bb.get()));
}
return s.toString();
}
}
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