63 lines
2.7 KiB
Java
63 lines
2.7 KiB
Java
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/**
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*
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* Copyright 2019 Paul Schaub
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.jivesoftware.smackx.omemo.util;
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import java.util.logging.Level;
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import java.util.logging.Logger;
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import org.jivesoftware.smackx.omemo.OmemoStore;
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import org.jivesoftware.smackx.omemo.internal.OmemoDevice;
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/**
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* This {@link StalenessStrategy} determines the staleness of a device by utilizing the ChainKey index of the sessions
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* sending chain. If the chain key index exceeds a certain value, the device is considered to be stale.
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* This means, that once we sent too many messages to the device without receiving an answer, we consider the device
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* stale.
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*/
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public class ChainKeyIndexStalenessStrategy<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Sess, T_Addr, T_ECPub, T_Bundle, T_Ciph> implements StalenessStrategy {
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private static final Logger LOGGER = Logger.getLogger(ChainKeyIndexStalenessStrategy.class.getName());
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private final OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Sess, T_Addr, T_ECPub, T_Bundle, T_Ciph> store;
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private final int maxChainKeyIndex;
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/**
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* Create a new {@link ChainKeyIndexStalenessStrategy}.
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*
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* @param store {@link OmemoStore} from which we can read the devices session.
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* @param maxChainKeyIndex the maximum value of messages we are allowed to send to the device unanswered before
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* we consider it stale.
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*/
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public ChainKeyIndexStalenessStrategy(OmemoStore<T_IdKeyPair, T_IdKey, T_PreKey, T_SigPreKey, T_Sess, T_Addr, T_ECPub, T_Bundle, T_Ciph> store, int maxChainKeyIndex) {
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this.store = store;
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this.maxChainKeyIndex = maxChainKeyIndex;
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}
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@Override
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public boolean isStale(OmemoDevice userDevice, OmemoDevice contactsDevice) {
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T_Sess sessionRecord = store.loadRawSession(userDevice, contactsDevice);
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if (sessionRecord == null) {
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return false;
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}
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int chainLength = store.keyUtil().lengthOfSessionSendingChain(sessionRecord);
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LOGGER.log(Level.FINE, "Staleness factor of OMEMO session between "
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+ userDevice + " and " + contactsDevice + ": " + chainLength + "/" + maxChainKeyIndex);
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return chainLength >= maxChainKeyIndex;
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}
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}
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