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105 lines
2.8 KiB
Java
105 lines
2.8 KiB
Java
/* ========================================================================
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* PlantUML : a free UML diagram generator
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* ========================================================================
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*
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* (C) Copyright 2009-2020, Arnaud Roques
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*
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* Project Info: http://plantuml.com
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*
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* If you like this project or if you find it useful, you can support us at:
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*
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* http://plantuml.com/patreon (only 1$ per month!)
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* http://plantuml.com/paypal
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*
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* This file is part of PlantUML.
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*
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* PlantUML is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* PlantUML distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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* License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
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* USA.
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*
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*
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* Original Author: Arnaud Roques
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*
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*
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*/
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package net.sourceforge.plantuml.dedication;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.UnsupportedEncodingException;
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import java.security.MessageDigest;
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import java.security.NoSuchAlgorithmException;
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import java.util.Random;
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public class DecoderInputStream extends InputStream {
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private final TurningBytes message;
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private final TurningBytes sha;
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private final Random rnd;
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private final InputStream source;
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public DecoderInputStream(InputStream source, String s) {
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this.source = source;
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try {
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final byte[] text = s.getBytes("UTF-8");
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final byte[] key = getSignatureSha512(text);
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this.rnd = new Random(getSeed(key));
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this.message = new TurningBytes(text);
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this.sha = new TurningBytes(key);
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} catch (UnsupportedEncodingException e) {
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e.printStackTrace();
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throw new UnsupportedOperationException(e);
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}
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}
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private static byte[] getSignatureSha512(byte[] bytes) {
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try {
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final MessageDigest msgDigest = MessageDigest.getInstance("SHA-512");
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msgDigest.update(bytes);
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return msgDigest.digest();
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} catch (NoSuchAlgorithmException e) {
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e.printStackTrace();
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throw new UnsupportedOperationException(e);
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}
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}
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private long getSeed(byte[] bytes) {
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long result = 17;
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for (byte b : bytes) {
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result = result * 37 + b;
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}
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return result;
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}
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private byte getNextByte() {
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return (byte) (rnd.nextInt() ^ message.nextByte() ^ sha.nextByte());
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}
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@Override
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public void close() throws IOException {
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source.close();
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}
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@Override
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public int read() throws IOException {
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int b = source.read();
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if (b == -1) {
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return -1;
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}
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b = (b ^ getNextByte()) & 0xFF;
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return b;
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}
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}
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