430 lines
15 KiB
Dart
430 lines
15 KiB
Dart
/*
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* Famedly Matrix SDK
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* Copyright (C) 2019, 2020 Famedly GmbH
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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 Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (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 Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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import 'dart:convert';
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import 'package:canonical_json/canonical_json.dart';
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import 'package:famedlysdk/famedlysdk.dart';
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import 'package:famedlysdk/matrix_api.dart';
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import 'package:olm/olm.dart' as olm;
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import './encryption.dart';
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class OlmManager {
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final Encryption encryption;
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Client get client => encryption.client;
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olm.Account _olmAccount;
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/// Returns the base64 encoded keys to store them in a store.
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/// This String should **never** leave the device!
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String get pickledOlmAccount =>
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enabled ? _olmAccount.pickle(client.userID) : null;
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String get fingerprintKey =>
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enabled ? json.decode(_olmAccount.identity_keys())['ed25519'] : null;
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String get identityKey =>
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enabled ? json.decode(_olmAccount.identity_keys())['curve25519'] : null;
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bool get enabled => _olmAccount != null;
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OlmManager(this.encryption);
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/// A map from Curve25519 identity keys to existing olm sessions.
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Map<String, List<olm.Session>> get olmSessions => _olmSessions;
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final Map<String, List<olm.Session>> _olmSessions = {};
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Future<void> init(String olmAccount) async {
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if (olmAccount == null) {
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try {
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await olm.init();
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_olmAccount = olm.Account();
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_olmAccount.create();
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if (await uploadKeys(uploadDeviceKeys: true) == false) {
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throw ('Upload key failed');
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}
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} catch (_) {
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_olmAccount?.free();
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_olmAccount = null;
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}
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} else {
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try {
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await olm.init();
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_olmAccount = olm.Account();
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_olmAccount.unpickle(client.userID, olmAccount);
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} catch (_) {
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_olmAccount?.free();
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_olmAccount = null;
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}
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}
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}
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/// Adds a signature to this json from this olm account.
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Map<String, dynamic> signJson(Map<String, dynamic> payload) {
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if (!enabled) throw ('Encryption is disabled');
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final Map<String, dynamic> unsigned = payload['unsigned'];
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final Map<String, dynamic> signatures = payload['signatures'];
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payload.remove('unsigned');
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payload.remove('signatures');
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final canonical = canonicalJson.encode(payload);
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final signature = _olmAccount.sign(String.fromCharCodes(canonical));
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if (signatures != null) {
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payload['signatures'] = signatures;
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} else {
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payload['signatures'] = <String, dynamic>{};
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}
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if (!payload['signatures'].containsKey(client.userID)) {
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payload['signatures'][client.userID] = <String, dynamic>{};
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}
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payload['signatures'][client.userID]['ed25519:${client.deviceID}'] =
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signature;
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if (unsigned != null) {
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payload['unsigned'] = unsigned;
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}
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return payload;
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}
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/// Checks the signature of a signed json object.
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bool checkJsonSignature(String key, Map<String, dynamic> signedJson,
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String userId, String deviceId) {
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if (!enabled) throw ('Encryption is disabled');
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final Map<String, dynamic> signatures = signedJson['signatures'];
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if (signatures == null || !signatures.containsKey(userId)) return false;
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signedJson.remove('unsigned');
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signedJson.remove('signatures');
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if (!signatures[userId].containsKey('ed25519:$deviceId')) return false;
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final String signature = signatures[userId]['ed25519:$deviceId'];
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final canonical = canonicalJson.encode(signedJson);
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final message = String.fromCharCodes(canonical);
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var isValid = false;
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final olmutil = olm.Utility();
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try {
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olmutil.ed25519_verify(key, message, signature);
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isValid = true;
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} catch (e) {
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isValid = false;
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print('[LibOlm] Signature check failed: ' + e.toString());
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} finally {
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olmutil.free();
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}
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return isValid;
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}
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/// Generates new one time keys, signs everything and upload it to the server.
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Future<bool> uploadKeys({bool uploadDeviceKeys = false, int oldKeyCount = 0}) async {
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if (!enabled) {
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return true;
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}
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// generate one-time keys
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// we generate 2/3rds of max, so that other keys people may still have can
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// still be used
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final oneTimeKeysCount = (_olmAccount.max_number_of_one_time_keys() * 2 / 3).floor() - oldKeyCount;
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_olmAccount.generate_one_time_keys(oneTimeKeysCount);
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final Map<String, dynamic> oneTimeKeys =
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json.decode(_olmAccount.one_time_keys());
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// now sign all the one-time keys
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final signedOneTimeKeys = <String, dynamic>{};
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for (final entry in oneTimeKeys['curve25519'].entries) {
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final key = entry.key;
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final value = entry.value;
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signedOneTimeKeys['signed_curve25519:$key'] = <String, dynamic>{};
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signedOneTimeKeys['signed_curve25519:$key'] = signJson({
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'key': value,
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});
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}
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// and now generate the payload to upload
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final keysContent = <String, dynamic>{
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if (uploadDeviceKeys)
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'device_keys': {
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'user_id': client.userID,
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'device_id': client.deviceID,
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'algorithms': [
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'm.olm.v1.curve25519-aes-sha2',
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'm.megolm.v1.aes-sha2'
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],
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'keys': <String, dynamic>{},
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},
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};
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if (uploadDeviceKeys) {
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final Map<String, dynamic> keys =
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json.decode(_olmAccount.identity_keys());
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for (final entry in keys.entries) {
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final algorithm = entry.key;
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final value = entry.value;
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keysContent['device_keys']['keys']['$algorithm:${client.deviceID}'] =
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value;
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}
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keysContent['device_keys'] =
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signJson(keysContent['device_keys'] as Map<String, dynamic>);
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}
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final response = await client.api.uploadDeviceKeys(
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deviceKeys: uploadDeviceKeys
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? MatrixDeviceKeys.fromJson(keysContent['device_keys'])
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: null,
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oneTimeKeys: signedOneTimeKeys,
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);
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_olmAccount.mark_keys_as_published();
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await client.database?.updateClientKeys(pickledOlmAccount, client.id);
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return response['signed_curve25519'] == oneTimeKeysCount;
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}
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void handleDeviceOneTimeKeysCount(Map<String, int> countJson) {
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if (!enabled) {
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return;
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}
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// Check if there are at least half of max_number_of_one_time_keys left on the server
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// and generate and upload more if not.
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if (countJson.containsKey('signed_curve25519') &&
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countJson['signed_curve25519'] <
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(_olmAccount.max_number_of_one_time_keys() / 2)) {
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uploadKeys(oldKeyCount: countJson['signed_curve25519']);
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}
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}
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void storeOlmSession(String curve25519IdentityKey, olm.Session session) {
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if (client.database == null) {
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return;
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}
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if (!_olmSessions.containsKey(curve25519IdentityKey)) {
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_olmSessions[curve25519IdentityKey] = [];
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}
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final ix = _olmSessions[curve25519IdentityKey]
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.indexWhere((s) => s.session_id() == session.session_id());
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if (ix == -1) {
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// add a new session
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_olmSessions[curve25519IdentityKey].add(session);
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} else {
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// update an existing session
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_olmSessions[curve25519IdentityKey][ix] = session;
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}
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final pickle = session.pickle(client.userID);
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client.database.storeOlmSession(
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client.id, curve25519IdentityKey, session.session_id(), pickle);
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}
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ToDeviceEvent _decryptToDeviceEvent(ToDeviceEvent event) {
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if (event.type != EventTypes.Encrypted) {
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return event;
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}
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if (event.content['algorithm'] != 'm.olm.v1.curve25519-aes-sha2') {
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throw ('Unknown algorithm: ${event.content}');
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}
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if (!event.content['ciphertext'].containsKey(identityKey)) {
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throw ("The message isn't sent for this device");
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}
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String plaintext;
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final String senderKey = event.content['sender_key'];
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final String body = event.content['ciphertext'][identityKey]['body'];
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final int type = event.content['ciphertext'][identityKey]['type'];
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if (type != 0 && type != 1) {
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throw ('Unknown message type');
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}
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var existingSessions = olmSessions[senderKey];
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if (existingSessions != null) {
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for (var session in existingSessions) {
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if (type == 0 && session.matches_inbound(body) == true) {
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plaintext = session.decrypt(type, body);
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storeOlmSession(senderKey, session);
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break;
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} else if (type == 1) {
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try {
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plaintext = session.decrypt(type, body);
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storeOlmSession(senderKey, session);
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break;
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} catch (_) {
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plaintext = null;
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}
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}
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}
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}
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if (plaintext == null && type != 0) {
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return event;
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}
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if (plaintext == null) {
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var newSession = olm.Session();
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try {
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newSession.create_inbound_from(_olmAccount, senderKey, body);
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_olmAccount.remove_one_time_keys(newSession);
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client.database?.updateClientKeys(pickledOlmAccount, client.id);
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plaintext = newSession.decrypt(type, body);
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storeOlmSession(senderKey, newSession);
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} catch (_) {
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newSession?.free();
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rethrow;
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}
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}
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final Map<String, dynamic> plainContent = json.decode(plaintext);
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if (plainContent.containsKey('sender') &&
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plainContent['sender'] != event.sender) {
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throw ("Message was decrypted but sender doesn't match");
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}
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if (plainContent.containsKey('recipient') &&
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plainContent['recipient'] != client.userID) {
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throw ("Message was decrypted but recipient doesn't match");
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}
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if (plainContent['recipient_keys'] is Map &&
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plainContent['recipient_keys']['ed25519'] is String &&
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plainContent['recipient_keys']['ed25519'] != fingerprintKey) {
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throw ("Message was decrypted but own fingerprint Key doesn't match");
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}
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return ToDeviceEvent(
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content: plainContent['content'],
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encryptedContent: event.content,
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type: plainContent['type'],
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sender: event.sender,
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);
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}
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Future<ToDeviceEvent> decryptToDeviceEvent(ToDeviceEvent event) async {
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if (event.type != EventTypes.Encrypted) {
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return event;
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}
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final senderKey = event.content['sender_key'];
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final loadFromDb = () async {
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if (client.database == null) {
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return false;
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}
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final sessions = await client.database.getSingleOlmSessions(
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client.id, senderKey, client.userID);
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if (sessions.isEmpty) {
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return false; // okay, can't do anything
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}
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_olmSessions[senderKey] = sessions;
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return true;
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};
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if (!_olmSessions.containsKey(senderKey)) {
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await loadFromDb();
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}
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event = _decryptToDeviceEvent(event);
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if (event.type != EventTypes.Encrypted || !(await loadFromDb())) {
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return event;
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}
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// retry to decrypt!
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return _decryptToDeviceEvent(event);
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}
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Future<void> startOutgoingOlmSessions(List<DeviceKeys> deviceKeys) async {
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var requestingKeysFrom = <String, Map<String, String>>{};
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for (var device in deviceKeys) {
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if (requestingKeysFrom[device.userId] == null) {
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requestingKeysFrom[device.userId] = {};
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}
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requestingKeysFrom[device.userId][device.deviceId] = 'signed_curve25519';
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}
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final response =
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await client.api.requestOneTimeKeys(requestingKeysFrom, timeout: 10000);
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for (var userKeysEntry in response.oneTimeKeys.entries) {
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final userId = userKeysEntry.key;
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for (var deviceKeysEntry in userKeysEntry.value.entries) {
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final deviceId = deviceKeysEntry.key;
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final fingerprintKey =
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client.userDeviceKeys[userId].deviceKeys[deviceId].ed25519Key;
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final identityKey =
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client.userDeviceKeys[userId].deviceKeys[deviceId].curve25519Key;
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for (Map<String, dynamic> deviceKey in deviceKeysEntry.value.values) {
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if (!checkJsonSignature(fingerprintKey, deviceKey, userId, deviceId)) {
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continue;
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}
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try {
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var session = olm.Session();
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session.create_outbound(_olmAccount, identityKey, deviceKey['key']);
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await storeOlmSession(identityKey, session);
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} catch (e) {
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print('[LibOlm] Could not create new outbound olm session: ' +
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e.toString());
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}
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}
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}
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}
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}
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Future<Map<String, dynamic>> encryptToDeviceMessagePayload(
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DeviceKeys device, String type, Map<String, dynamic> payload) async {
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var sess = olmSessions[device.curve25519Key];
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if (sess == null || sess.isEmpty) {
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final sessions = await client.database
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.getSingleOlmSessions(client.id, device.curve25519Key, client.userID);
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if (sessions.isEmpty) {
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throw ('No olm session found');
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}
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sess = _olmSessions[device.curve25519Key] = sessions;
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}
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sess.sort((a, b) => a.session_id().compareTo(b.session_id()));
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final fullPayload = {
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'type': type,
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'content': payload,
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'sender': client.userID,
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'keys': {'ed25519': fingerprintKey},
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'recipient': device.userId,
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'recipient_keys': {'ed25519': device.ed25519Key},
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};
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final encryptResult = sess.first.encrypt(json.encode(fullPayload));
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storeOlmSession(device.curve25519Key, sess.first);
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final encryptedBody = <String, dynamic>{
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'algorithm': 'm.olm.v1.curve25519-aes-sha2',
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'sender_key': identityKey,
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'ciphertext': <String, dynamic>{},
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};
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encryptedBody['ciphertext'][device.curve25519Key] = {
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'type': encryptResult.type,
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'body': encryptResult.body,
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};
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return encryptedBody;
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}
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Future<Map<String, dynamic>> encryptToDeviceMessage(
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List<DeviceKeys> deviceKeys,
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String type,
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Map<String, dynamic> payload) async {
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var data = <String, Map<String, Map<String, dynamic>>>{};
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final deviceKeysWithoutSession = List<DeviceKeys>.from(deviceKeys);
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deviceKeysWithoutSession.removeWhere((DeviceKeys deviceKeys) =>
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olmSessions.containsKey(deviceKeys.curve25519Key));
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if (deviceKeysWithoutSession.isNotEmpty) {
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await startOutgoingOlmSessions(deviceKeysWithoutSession);
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}
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for (final device in deviceKeys) {
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if (!data.containsKey(device.userId)) {
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data[device.userId] = {};
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}
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try {
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data[device.userId][device.deviceId] =
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await encryptToDeviceMessagePayload(device, type, payload);
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} catch (e) {
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print('[LibOlm] Error encrypting to-device event: ' + e.toString());
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continue;
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}
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}
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return data;
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}
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void dispose() {
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for (final sessions in olmSessions.values) {
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for (final sess in sessions) {
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sess.free();
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}
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}
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_olmAccount?.free();
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_olmAccount = null;
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}
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}
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