mirror of
https://github.com/oxen-io/session-android.git
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97 lines
3.2 KiB
Java
97 lines
3.2 KiB
Java
/**
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* Copyright (C) 2011 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.thoughtcrime.securesms.database;
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import org.thoughtcrime.securesms.crypto.MasterCipher;
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import org.thoughtcrime.securesms.crypto.MasterSecret;
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import org.thoughtcrime.securesms.crypto.SessionCipher;
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import org.thoughtcrime.securesms.util.Conversions;
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import org.thoughtcrime.securesms.util.Util;
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import javax.crypto.spec.SecretKeySpec;
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/**
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* Represents the currently negotiated session key for a given
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* local key id and remote key id. This is stored encrypted on
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* disk.
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*
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* @author Moxie Marlinspike
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*/
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public class SessionKey {
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private int localKeyId;
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private int remoteKeyId;
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private SecretKeySpec cipherKey;
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private SecretKeySpec macKey;
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private MasterCipher masterCipher;
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public SessionKey(int localKeyId, int remoteKeyId, SecretKeySpec cipherKey, SecretKeySpec macKey, MasterSecret masterSecret) {
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this.localKeyId = localKeyId;
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this.remoteKeyId = remoteKeyId;
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this.cipherKey = cipherKey;
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this.macKey = macKey;
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this.masterCipher = new MasterCipher(masterSecret);
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}
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public SessionKey(byte[] bytes, MasterSecret masterSecret) {
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this.masterCipher = new MasterCipher(masterSecret);
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deserialize(bytes);
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}
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public byte[] serialize() {
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byte[] localKeyIdBytes = Conversions.mediumToByteArray(localKeyId);
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byte[] remoteKeyIdBytes = Conversions.mediumToByteArray(remoteKeyId);
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byte[] cipherKeyBytes = cipherKey.getEncoded();
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byte[] macKeyBytes = macKey.getEncoded();
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byte[] combined = Util.combine(localKeyIdBytes, remoteKeyIdBytes, cipherKeyBytes, macKeyBytes);
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return masterCipher.encryptBytes(combined);
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}
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private void deserialize(byte[] bytes) {
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byte[] decrypted = masterCipher.encryptBytes(bytes);
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this.localKeyId = Conversions.byteArrayToMedium(decrypted, 0);
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this.remoteKeyId = Conversions.byteArrayToMedium(decrypted, 3);
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byte[] keyBytes = new byte[SessionCipher.CIPHER_KEY_LENGTH];
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System.arraycopy(decrypted, 6, keyBytes, 0, keyBytes.length);
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byte[] macBytes = new byte[SessionCipher.MAC_KEY_LENGTH];
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System.arraycopy(decrypted, 6 + keyBytes.length, macBytes, 0, macBytes.length);
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this.cipherKey = new SecretKeySpec(keyBytes, "AES");
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this.macKey = new SecretKeySpec(macBytes, "HmacSHA1");
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}
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public int getLocalKeyId() {
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return this.localKeyId;
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}
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public int getRemoteKeyId() {
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return this.remoteKeyId;
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}
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public SecretKeySpec getCipherKey() {
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return this.cipherKey;
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}
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public SecretKeySpec getMacKey() {
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return this.macKey;
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}
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}
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