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plantuml/src/net/sourceforge/plantuml/dedication/DecoderInputStream.java
2019-01-16 19:34:41 +01:00

105 lines
2.8 KiB
Java

/* ========================================================================
* PlantUML : a free UML diagram generator
* ========================================================================
*
* (C) Copyright 2009-2020, Arnaud Roques
*
* Project Info: http://plantuml.com
*
* If you like this project or if you find it useful, you can support us at:
*
* http://plantuml.com/patreon (only 1$ per month!)
* http://plantuml.com/paypal
*
* This file is part of PlantUML.
*
* PlantUML 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 3 of the License, or
* (at your option) any later version.
*
* PlantUML 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 library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*
*
* Original Author: Arnaud Roques
*
*
*/
package net.sourceforge.plantuml.dedication;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Random;
public class DecoderInputStream extends InputStream {
private final TurningBytes message;
private final TurningBytes sha;
private final Random rnd;
private final InputStream source;
public DecoderInputStream(InputStream source, String s) {
this.source = source;
try {
final byte[] text = s.getBytes("UTF-8");
final byte[] key = getSignatureSha512(text);
this.rnd = new Random(getSeed(key));
this.message = new TurningBytes(text);
this.sha = new TurningBytes(key);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
throw new UnsupportedOperationException(e);
}
}
private static byte[] getSignatureSha512(byte[] bytes) {
try {
final MessageDigest msgDigest = MessageDigest.getInstance("SHA-512");
msgDigest.update(bytes);
return msgDigest.digest();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
throw new UnsupportedOperationException(e);
}
}
private long getSeed(byte[] bytes) {
long result = 17;
for (byte b : bytes) {
result = result * 37 + b;
}
return result;
}
private byte getNextByte() {
return (byte) (rnd.nextInt() ^ message.nextByte() ^ sha.nextByte());
}
@Override
public void close() throws IOException {
source.close();
}
@Override
public int read() throws IOException {
int b = source.read();
if (b == -1) {
return -1;
}
b = (b ^ getNextByte()) & 0xFF;
return b;
}
}