forked from I2P_Developers/i2p.i2p
RoutingKeyGenerator:
- Move from core to RouterKeyGenerator in router.jar
- Leave RoutingKeyGenerator as a simple abstract class
- DatabaseEntry now uses timestamp instead of mod data
to determine if mod data has changed. Don't expose
mod data to DatabaseEntry any more.
- I2PAppContext.routingKeyGenerator() now returns null;
you must be in RouterContext to get a generator.
This commit is contained in:
224
router/java/src/net/i2p/data/router/RouterKeyGenerator.java
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224
router/java/src/net/i2p/data/router/RouterKeyGenerator.java
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package net.i2p.data.router;
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/*
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* free (adj.): unencumbered; not under the control of others
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* Written by jrandom in 2003 and released into the public domain
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* with no warranty of any kind, either expressed or implied.
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* It probably won't make your computer catch on fire, or eat
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* your children, but it might. Use at your own risk.
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*
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*/
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import java.text.SimpleDateFormat;
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import java.util.Calendar;
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import java.util.Date;
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import java.util.Arrays;
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import java.util.GregorianCalendar;
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import java.util.Locale;
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import java.util.TimeZone;
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import net.i2p.I2PAppContext;
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import net.i2p.crypto.SHA256Generator;
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import net.i2p.data.Hash;
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import net.i2p.data.RoutingKeyGenerator;
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import net.i2p.util.HexDump;
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import net.i2p.util.Log;
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/**
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* Component to manage the munging of hashes into routing keys - given a hash,
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* perform some consistent transformation against it and return the result.
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* This transformation is fed by the current "mod data".
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*
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* Right now the mod data is the current date (GMT) as a string: "yyyyMMdd",
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* and the transformation takes the original hash, appends the bytes of that mod data,
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* then returns the SHA256 of that concatenation.
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*
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* Do we want this to simply do the XOR of the SHA256 of the current mod data and
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* the key? does that provide the randomization we need? It'd save an SHA256 op.
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* Bah, too much effort to think about for so little gain. Other algorithms may come
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* into play layer on about making periodic updates to the routing key for data elements
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* to mess with Sybil. This may be good enough though.
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*
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* Also - the method generateDateBasedModData() should be called after midnight GMT
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* once per day to generate the correct routing keys!
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*
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* @since 0.9.16 moved from net.i2p.data.RoutingKeyGenerator..
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*
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*/
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public class RouterKeyGenerator extends RoutingKeyGenerator {
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private final Log _log;
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private final I2PAppContext _context;
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public RouterKeyGenerator(I2PAppContext context) {
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_log = context.logManager().getLog(RoutingKeyGenerator.class);
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_context = context;
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// ensure non-null mod data
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generateDateBasedModData();
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}
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private volatile byte _currentModData[];
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private volatile byte _nextModData[];
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private volatile long _nextMidnight;
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private volatile long _lastChanged;
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private final static Calendar _cal = GregorianCalendar.getInstance(TimeZone.getTimeZone("GMT"));
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private static final String FORMAT = "yyyyMMdd";
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private static final int LENGTH = FORMAT.length();
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private final static SimpleDateFormat _fmt = new SimpleDateFormat(FORMAT, Locale.US);
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static {
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// make sure GMT is set, azi2phelper Vuze plugin is disabling static JVM TZ setting in Router.java
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_fmt.setCalendar(_cal);
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}
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/**
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* The current (today's) mod data.
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* Warning - not a copy, do not corrupt.
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*
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* @return non-null, 8 bytes
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*/
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public byte[] getModData() {
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return _currentModData;
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}
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/**
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* Tomorrow's mod data.
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* Warning - not a copy, do not corrupt.
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* For debugging use only.
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*
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* @return non-null, 8 bytes
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* @since 0.9.10
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*/
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public byte[] getNextModData() {
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return _nextModData;
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}
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public long getLastChanged() {
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return _lastChanged;
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}
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/**
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* How long until midnight (ms)
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*
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* @return could be slightly negative
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* @since 0.9.10 moved from UpdateRoutingKeyModifierJob
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*/
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public long getTimeTillMidnight() {
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return _nextMidnight - _context.clock().now();
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}
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/**
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* Set _cal to midnight for the time given.
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* Caller must synch.
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* @since 0.9.10
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*/
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private void setCalToPreviousMidnight(long now) {
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_cal.setTime(new Date(now));
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_cal.set(Calendar.YEAR, _cal.get(Calendar.YEAR)); // gcj <= 4.0 workaround
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_cal.set(Calendar.DAY_OF_YEAR, _cal.get(Calendar.DAY_OF_YEAR)); // gcj <= 4.0 workaround
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_cal.set(Calendar.HOUR_OF_DAY, 0);
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_cal.set(Calendar.MINUTE, 0);
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_cal.set(Calendar.SECOND, 0);
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_cal.set(Calendar.MILLISECOND, 0);
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}
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/**
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* Generate mod data from _cal.
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* Caller must synch.
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* @since 0.9.10
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*/
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private byte[] generateModDataFromCal() {
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Date today = _cal.getTime();
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String modVal = _fmt.format(today);
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if (modVal.length() != LENGTH)
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throw new IllegalStateException();
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byte[] mod = new byte[LENGTH];
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for (int i = 0; i < LENGTH; i++)
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mod[i] = (byte)(modVal.charAt(i) & 0xFF);
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return mod;
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}
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/**
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* Update the current modifier data with some bytes derived from the current
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* date (yyyyMMdd in GMT)
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*
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* @return true if changed
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*/
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public synchronized boolean generateDateBasedModData() {
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long now = _context.clock().now();
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setCalToPreviousMidnight(now);
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byte[] mod = generateModDataFromCal();
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boolean changed = !Arrays.equals(_currentModData, mod);
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if (changed) {
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// add a day and store next midnight and mod data for convenience
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_cal.add(Calendar.DATE, 1);
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_nextMidnight = _cal.getTime().getTime();
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byte[] next = generateModDataFromCal();
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_currentModData = mod;
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_nextModData = next;
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// ensure version is bumped
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if (_lastChanged == now)
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now++;
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_lastChanged = now;
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if (_log.shouldLog(Log.INFO))
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_log.info("Routing modifier generated: " + HexDump.dump(mod));
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}
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return changed;
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}
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/**
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* Generate a modified (yet consistent) hash from the origKey by generating the
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* SHA256 of the targetKey with the current modData appended to it
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*
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* This makes Sybil's job a lot harder, as she needs to essentially take over the
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* whole keyspace.
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*
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* @throws IllegalArgumentException if origKey is null
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*/
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public Hash getRoutingKey(Hash origKey) {
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return getKey(origKey, _currentModData);
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}
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/**
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* Get the routing key using tomorrow's modData, not today's
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*
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* @since 0.9.10
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*/
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public Hash getNextRoutingKey(Hash origKey) {
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return getKey(origKey, _nextModData);
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}
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/**
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* Generate a modified (yet consistent) hash from the origKey by generating the
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* SHA256 of the targetKey with the specified modData appended to it
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*
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* @throws IllegalArgumentException if origKey is null
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*/
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private static Hash getKey(Hash origKey, byte[] modData) {
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if (origKey == null) throw new IllegalArgumentException("Original key is null");
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byte modVal[] = new byte[Hash.HASH_LENGTH + LENGTH];
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System.arraycopy(origKey.getData(), 0, modVal, 0, Hash.HASH_LENGTH);
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System.arraycopy(modData, 0, modVal, Hash.HASH_LENGTH, LENGTH);
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return SHA256Generator.getInstance().calculateHash(modVal);
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}
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/****
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public static void main(String args[]) {
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Hash k1 = new Hash();
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byte k1d[] = new byte[Hash.HASH_LENGTH];
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RandomSource.getInstance().nextBytes(k1d);
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k1.setData(k1d);
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for (int i = 0; i < 10; i++) {
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System.out.println("K1: " + k1);
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Hash k1m = RoutingKeyGenerator.getInstance().getRoutingKey(k1);
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System.out.println("MOD: " + new String(RoutingKeyGenerator.getInstance().getModData()));
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System.out.println("K1M: " + k1m);
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}
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try {
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Thread.sleep(2000);
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} catch (Throwable t) { // nop
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}
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}
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****/
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}
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