kopia lustrzana https://github.com/ryukoposting/Signal-Android
74 wiersze
2.2 KiB
Java
74 wiersze
2.2 KiB
Java
/**
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* Copyright (C) 2014 Open Whisper Systems
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*
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* This program is free software: you can redistribute it and/or modify
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* it 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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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package org.whispersystems.libaxolotl.ratchet;
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import org.whispersystems.libaxolotl.kdf.DerivedSecrets;
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import org.whispersystems.libaxolotl.kdf.HKDF;
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import java.security.InvalidKeyException;
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import java.security.NoSuchAlgorithmException;
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import javax.crypto.Mac;
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import javax.crypto.spec.SecretKeySpec;
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public class ChainKey {
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private static final byte[] MESSAGE_KEY_SEED = {0x01};
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private static final byte[] CHAIN_KEY_SEED = {0x02};
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private final byte[] key;
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private final int index;
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public ChainKey(byte[] key, int index) {
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this.key = key;
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this.index = index;
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}
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public byte[] getKey() {
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return key;
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}
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public int getIndex() {
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return index;
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}
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public ChainKey getNextChainKey() {
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byte[] nextKey = getBaseMaterial(CHAIN_KEY_SEED);
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return new ChainKey(nextKey, index + 1);
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}
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public MessageKeys getMessageKeys() {
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HKDF kdf = new HKDF();
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byte[] inputKeyMaterial = getBaseMaterial(MESSAGE_KEY_SEED);
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DerivedSecrets keyMaterial = kdf.deriveSecrets(inputKeyMaterial, "WhisperMessageKeys".getBytes());
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return new MessageKeys(keyMaterial.getCipherKey(), keyMaterial.getMacKey(), index);
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}
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private byte[] getBaseMaterial(byte[] seed) {
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try {
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Mac mac = Mac.getInstance("HmacSHA256");
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mac.init(new SecretKeySpec(key, "HmacSHA256"));
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return mac.doFinal(seed);
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} catch (NoSuchAlgorithmException | InvalidKeyException e) {
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throw new AssertionError(e);
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}
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}
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}
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