104 lines
4.7 KiB
Java
104 lines
4.7 KiB
Java
/**
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* Copyright (C) 2011 Whisper Systems
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* Copyright (C) 2013 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.thoughtcrime.securesms.crypto;
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import android.app.AlertDialog;
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import android.content.Context;
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import android.content.DialogInterface;
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import org.thoughtcrime.securesms.R;
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import org.thoughtcrime.securesms.crypto.protocol.KeyExchangeMessageV2;
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import org.thoughtcrime.securesms.recipients.Recipient;
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import org.thoughtcrime.securesms.sms.MessageSender;
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import org.thoughtcrime.securesms.sms.OutgoingKeyExchangeMessage;
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import org.thoughtcrime.securesms.util.Dialogs;
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import org.whispersystems.libaxolotl.IdentityKeyPair;
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import org.whispersystems.libaxolotl.ecc.Curve;
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import org.whispersystems.libaxolotl.ecc.ECKeyPair;
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import org.whispersystems.textsecure.crypto.MasterSecret;
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import org.whispersystems.textsecure.storage.RecipientDevice;
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import org.whispersystems.textsecure.storage.SessionRecordV2;
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import java.security.NoSuchAlgorithmException;
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import java.security.SecureRandom;
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public class KeyExchangeInitiator {
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public static void initiate(final Context context, final MasterSecret masterSecret, final Recipient recipient, boolean promptOnExisting) {
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if (promptOnExisting && hasInitiatedSession(context, masterSecret, recipient)) {
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AlertDialog.Builder dialog = new AlertDialog.Builder(context);
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dialog.setTitle(R.string.KeyExchangeInitiator_initiate_despite_existing_request_question);
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dialog.setMessage(R.string.KeyExchangeInitiator_youve_already_sent_a_session_initiation_request_to_this_recipient_are_you_sure);
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dialog.setIcon(Dialogs.resolveIcon(context, R.attr.dialog_alert_icon));
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dialog.setCancelable(true);
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dialog.setPositiveButton(R.string.KeyExchangeInitiator_send, new DialogInterface.OnClickListener() {
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public void onClick(DialogInterface dialog, int which) {
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initiateKeyExchange(context, masterSecret, recipient);
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}
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});
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dialog.setNegativeButton(android.R.string.cancel, null);
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dialog.show();
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} else {
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initiateKeyExchange(context, masterSecret, recipient);
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}
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}
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private static void initiateKeyExchange(Context context, MasterSecret masterSecret, Recipient recipient) {
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int sequence = getRandomSequence();
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int flags = KeyExchangeMessageV2.INITIATE_FLAG;
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ECKeyPair baseKey = Curve.generateKeyPair(true);
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ECKeyPair ephemeralKey = Curve.generateKeyPair(true);
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IdentityKeyPair identityKey = IdentityKeyUtil.getIdentityKeyPair(context, masterSecret);
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KeyExchangeMessageV2 message = new KeyExchangeMessageV2(sequence, flags,
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baseKey.getPublicKey(),
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ephemeralKey.getPublicKey(),
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identityKey.getPublicKey());
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OutgoingKeyExchangeMessage textMessage = new OutgoingKeyExchangeMessage(recipient, message.serialize());
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RecipientDevice recipientDevice = new RecipientDevice(recipient.getRecipientId(), RecipientDevice.DEFAULT_DEVICE_ID);
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SessionRecordV2 sessionRecordV2 = new SessionRecordV2(context, masterSecret, recipientDevice);
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sessionRecordV2.getSessionState().setPendingKeyExchange(sequence, baseKey, ephemeralKey, identityKey);
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sessionRecordV2.save();
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MessageSender.send(context, masterSecret, textMessage, -1, false);
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}
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private static boolean hasInitiatedSession(Context context, MasterSecret masterSecret,
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Recipient recipient)
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{
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RecipientDevice recipientDevice = new RecipientDevice(recipient.getRecipientId(), RecipientDevice.DEFAULT_DEVICE_ID);
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return
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new SessionRecordV2(context, masterSecret, recipientDevice)
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.getSessionState()
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.hasPendingKeyExchange();
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}
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private static int getRandomSequence() {
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try {
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SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
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int candidate = Math.abs(random.nextInt());
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return candidate % 65535;
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} catch (NoSuchAlgorithmException 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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