✨ Keypair Infra
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211
lib/providers/keypair.dart
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211
lib/providers/keypair.dart
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import 'dart:async';
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import 'dart:convert';
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import 'package:drift/drift.dart';
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import 'package:flutter/material.dart';
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import 'package:provider/provider.dart';
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import 'package:surface/database/database.dart';
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import 'package:surface/logger.dart';
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import 'package:surface/providers/database.dart';
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import 'package:surface/providers/userinfo.dart';
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import 'package:surface/providers/websocket.dart';
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import 'package:surface/types/keypair.dart';
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import 'package:fast_rsa/fast_rsa.dart';
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import 'package:surface/types/websocket.dart';
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import 'package:uuid/uuid.dart';
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// Currently the keypair only provide RSA encryption
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// Supported by the `fast_rsa` package
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class KeyPairProvider {
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late final DatabaseProvider _dt;
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late final UserProvider _ua;
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late final WebSocketProvider _ws;
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SnKeyPair? activeKp;
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KeyPairProvider(BuildContext context) {
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_dt = context.read<DatabaseProvider>();
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_ua = context.read<UserProvider>();
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_ws = context.read<WebSocketProvider>();
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reloadActive();
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}
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void listen() {
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_ws.pk.stream.listen((event) {
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switch (event.method) {
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case 'kex.ack':
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ackKeyExchange(event);
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break;
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case 'key.ask':
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replyAskKeyExchange(event);
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break;
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}
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});
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}
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Future<String> decryptText(String text, String kpId) async {
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final kp = await (_dt.db.snLocalKeyPair.select()
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..where((e) => e.id.equals(kpId)))
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.getSingleOrNull();
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if (kp == null) throw Exception('Key pair not found');
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return await RSA.decryptPKCS1v15(text, kp.privateKey!);
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}
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Future<String> encryptText(String text) async {
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if (activeKp == null) throw Exception('No active key pair');
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return await RSA.encryptPKCS1v15(text, activeKp!.publicKey);
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}
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final Map<String, Completer<SnKeyPair>> _requests = {};
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Future<SnKeyPair> askKeyExchange(int kpOwner, String kpId) async {
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if (_requests.containsKey(kpId)) return await _requests[kpId]!.future;
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final completer = Completer<SnKeyPair>();
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_requests[kpId] = completer;
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_ws.conn?.sink.add(
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jsonEncode(WebSocketPackage(
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method: 'key.ask',
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endpoint: 'id',
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payload: {
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'keypair_id': kpId,
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'user_id': kpOwner,
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},
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)),
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);
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return Future.any([
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_requests[kpId]!.future,
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Future.delayed(const Duration(seconds: 60), () {
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_requests.remove(kpId);
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throw TimeoutException("Key exchange timed out");
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}),
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]);
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}
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Future<void> ackKeyExchange(WebSocketPackage pkt) async {
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if (pkt.payload == null) return;
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final kpMeta = SnKeyPair(
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id: pkt.payload!['keypair_id'] as String,
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accountId: pkt.payload!['user_id'] as int,
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publicKey: pkt.payload!['public_key'] as String,
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privateKey: pkt.payload?['private_key'] as String?,
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);
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if (_requests.containsKey(kpMeta.id)) {
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_requests[kpMeta.id]!.complete(kpMeta);
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_requests.remove(kpMeta.id);
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}
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// Save the keypair to the local database
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await _dt.db.snLocalKeyPair.insertOne(
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SnLocalKeyPairCompanion.insert(
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id: kpMeta.id,
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accountId: kpMeta.accountId,
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publicKey: kpMeta.publicKey,
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privateKey: Value(kpMeta.privateKey),
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),
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onConflict: DoUpdate(
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(_) => SnLocalKeyPairCompanion.custom(
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publicKey: Constant(kpMeta.publicKey),
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privateKey: Constant(kpMeta.privateKey),
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),
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),
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);
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}
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Future<void> replyAskKeyExchange(WebSocketPackage pkt) async {
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final kpId = pkt.payload!['keypair_id'] as String;
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final userId = pkt.payload!['user_id'] as int;
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final clientId = pkt.payload!['client_id'] as String;
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final localKp = await (_dt.db.snLocalKeyPair.select()
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..where((e) => e.id.equals(kpId))
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..limit(1))
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.getSingleOrNull();
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if (localKp == null) return;
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logging.info(
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'[Kex] Reply to key exchange request of $kpId from user $userId',
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);
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// We do not give the private key to the client
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_ws.conn?.sink.add(jsonEncode(
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WebSocketPackage(
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method: 'kex.ack',
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endpoint: 'id',
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payload: {
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'keypair_id': localKp.id,
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'user_id': localKp.accountId,
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'public_key': localKp.publicKey,
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'client_id': clientId,
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},
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).toJson(),
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));
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}
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Future<SnKeyPair?> reloadActive({bool autoEnroll = true}) async {
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final kp = await (_dt.db.snLocalKeyPair.select()
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..where((e) => e.accountId.equals(_ua.user!.id))
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..where((e) => e.privateKey.isNotNull())
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..limit(1))
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.getSingleOrNull();
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if (kp != null) {
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activeKp = SnKeyPair(
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id: kp.id,
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accountId: kp.accountId,
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publicKey: kp.publicKey,
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privateKey: kp.privateKey,
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);
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}
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if (kp == null && autoEnroll) {
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return await enrollNew();
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}
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return activeKp;
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}
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Future<SnKeyPair> enrollNew() async {
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if (!_ua.isAuthorized) throw Exception('Unauthorized');
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final existsOne = await (_dt.db.snLocalKeyPair.select()
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..where((e) => e.accountId.equals(_ua.user!.id))
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..where((e) => e.privateKey.isNotNull())
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..limit(1))
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.getSingleOrNull();
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final id = existsOne?.id ?? const Uuid().v4();
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final kp = await RSA.generate(2048);
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final kpMeta = SnKeyPair(
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id: id,
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accountId: _ua.user!.id,
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publicKey: kp.publicKey,
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privateKey: kp.privateKey,
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);
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// Save the keypair to the local database
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// If there is already one with private key, it will be overwritten
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await _dt.db.snLocalKeyPair.insertOne(
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SnLocalKeyPairCompanion.insert(
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id: kpMeta.id,
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accountId: kpMeta.accountId,
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publicKey: kpMeta.publicKey,
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privateKey: Value(kpMeta.privateKey),
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),
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onConflict: DoUpdate(
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(_) => SnLocalKeyPairCompanion.custom(
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publicKey: Constant(kpMeta.publicKey),
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privateKey: Constant(kpMeta.privateKey),
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),
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),
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);
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await reloadActive(autoEnroll: false);
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return kpMeta;
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}
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}
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