add support for initializing and resetting crypto identity

Fixes #137

lib/controllers/client.dart

@@ -31,6 +31,7 @@ import "package:nexus/models/requests/get_room_state.dart";
 import "package:nexus/models/requests/get_space_hierarchy.dart";
 import "package:nexus/models/requests/join_room.dart";
 import "package:nexus/models/profile_response.dart";
+import "package:nexus/models/recovery_key.dart";
 import "package:nexus/models/requests/oauth/exchange_token.dart";
 import "package:nexus/models/requests/oauth/get_auth_url.dart";
 import "package:nexus/models/requests/oauth/register_client.dart";
@@ -190,6 +191,33 @@ class ClientController extends AsyncNotifier<int> {
     }
   }
 
+  Future<RecoveryKey> generateRecoveryKey({String passphrase = ""}) async =>
+      .fromJson(
+        await _sendCommand("generate_recovery_key", {"passphrase": passphrase}),
+      );
+
+  Future<void> resetEncryption(RecoveryKey key) =>
+      _sendCommand("reset_encryption", key.toJson());
+
+  Future<Uri?> getCrossSigningResetUrl(Uri homeserver) async {
+    const action = "org.matrix.cross_signing_reset";
+    final oauth = (await _sendCommand("get_login_flows", {
+      "homeserver_url": homeserver.toString(),
+    }))["oauth"];
+
+    if (oauth?["account_management_uri"] case final String uri
+        when (oauth["account_management_actions_supported"] as List?)?.contains(
+              action,
+            ) ??
+            false) {
+      final parsed = Uri.parse(uri);
+      return parsed.replace(
+        queryParameters: {...parsed.queryParameters, "action": action},
+      );
+    }
+    return null;
+  }
+
   Future<String> joinRoom(JoinRoomRequest request) async =>
       (await _sendCommand("join_room", request.toJson()))["room_id"];
 

lib/controllers/settings_sections.dart

@@ -22,6 +22,8 @@ import "package:nexus/models/room_order.dart";
 import "package:nexus/models/settings_category.dart";
 import "package:nexus/main.dart";
 import "package:nexus/widgets/settings/dialog_list_tile.dart";
+import "package:nexus/widgets/reset_encryption_sheet.dart";
+import "package:nexus/helpers/extensions/show_adaptive_sheet.dart";
 
 class SettingsSectionsController
     extends AsyncNotifier<IMap<String, IList<SettingsCategory>>> {
@@ -312,6 +314,21 @@ class SettingsSectionsController
             title: "Other",
             icon: Icons.key,
             settings: .new([
+              .new(
+                title: "Reset Encryption Identity",
+                description: "Replace your encryption identity and recovery key with new ones, if you've lost your recovery key or your encryption is broken.",
+                builder: (title, description, icon) => Builder(
+                  builder: (context) => M3EButton.icon(
+                    onPressed: () => context.showAdaptiveSheet(
+                      (_) => const ResetEncryptionSheet(),
+                    ),
+                    label: Text(title),
+                    icon: Icon(icon),
+                    tooltip: description,
+                  ),
+                ),
+                icon: Icons.key_off,
+              ),
               .new(
                 title: "Log Out",
                 description:

lib/models/client_state.dart

@@ -12,9 +12,23 @@ class const ClientState({
   required final String? userId,
   required final String? deviceId,
   required final String? homeserverUrl,
+  final VerificationState verificationState = const .new(),
 }) with _$ClientState {
   Map<String, Object?> toJson() => _$ClientStateToJson(this);
 
   factory ClientState.fromJson(Map<String, Object?> json) =>
       _$ClientStateFromJson(json);
 }
+
+@Freezed(toJson: false, fromJson: false)
+@JsonSerializable()
+class const VerificationState({
+  final bool stateChecked = false,
+  final bool hasCrossSigning = false,
+  @JsonKey(name: "has_ssss") final bool hasSecretStorage = false,
+}) with _$VerificationState {
+  Map<String, Object?> toJson() => _$VerificationStateToJson(this);
+
+  factory VerificationState.fromJson(Map<String, Object?> json) =>
+      _$VerificationStateFromJson(json);
+}

lib/models/gomuks_exception.dart

@@ -6,6 +6,12 @@ class GomuksException implements Exception {
   String? get errorCode =>
       RegExp(r"^(M_[A-Z_]+)").firstMatch(message)?.group(1);
 
+  /// The HTTP status code of the failed request
+  int? get statusCode => switch (RegExp(r"HTTP (\d{3})").firstMatch(message)) {
+    final match? => int.parse(match.group(1)!),
+    null => null,
+  };
+
   @override
   String toString() => message;
 }

lib/models/recovery_key.dart

@@ -0,0 +1,19 @@
+import "package:fast_immutable_collections/fast_immutable_collections.dart";
+import "package:freezed_annotation/freezed_annotation.dart";
+
+part "recovery_key.freezed.dart";
+part "recovery_key.g.dart";
+
+@Freezed(toJson: false, fromJson: false)
+@JsonSerializable(includeIfNull: false)
+class const RecoveryKey({
+  required final String recoveryKey,
+
+  required final IMap<String, dynamic> crossSigningKeys,
+  final IMap<String, dynamic>? passphraseMeta,
+}) with _$RecoveryKey {
+  Map<String, Object?> toJson() => _$RecoveryKeyToJson(this);
+
+  factory RecoveryKey.fromJson(Map<String, Object?> json) =>
+      _$RecoveryKeyFromJson(json);
+}

lib/widgets/pages/verify.dart

@@ -2,9 +2,14 @@ import "package:material_ui/material_ui.dart";
 import "package:flutter_hooks/flutter_hooks.dart";
 import "package:hooks_riverpod/hooks_riverpod.dart";
 import "package:nexus/controllers/client.dart";
+import "package:nexus/controllers/client_state.dart";
+import "package:nexus/models/client_state.dart";
+import "package:nexus/helpers/extensions/show_adaptive_sheet.dart";
+import "package:nexus/widgets/loading.dart";
 import "package:nexus/widgets/pages/settings.dart";
 import "package:nexus/widgets/appbar.dart";
 import "package:nexus/helpers/required_validator_helper.dart";
+import "package:nexus/widgets/reset_encryption_sheet.dart";
 
 class const VerifyPage({super.key}) extends HookConsumerWidget {
   @override
@@ -13,6 +18,11 @@ class const VerifyPage({super.key}) extends HookConsumerWidget {
     final isLoading = useState(false);
     final inputError = useState<String?>(null);
     final formKey = useRef(GlobalKey<FormState>());
+    final verificationState = ref.watch(
+      ClientStateController.provider.select(
+        (state) => state?.verificationState,
+      ),
+    );
 
     Future<void> verify() async {
       isLoading.value = true;
@@ -40,45 +50,65 @@ class const VerifyPage({super.key}) extends HookConsumerWidget {
           ),
         ]),
       ),
-      body: AlertDialog(
+      body: switch (verificationState) {
-        insetPadding: .symmetric(vertical: 12, horizontal: 32),
+        null || VerificationState(stateChecked: false) => const Loading(),
-        scrollable: true,
+        // Nothing to verify with yet, so go straight to setting it up.
-        title: Text("Verify"),
+        VerificationState(hasSecretStorage: false) => Dialog(
-        content: Form(
+          insetPadding: const .symmetric(vertical: 12, horizontal: 32),
-          key: formKey.value,
+          child: ConstrainedBox(
-          child: Column(
+            constraints: const .new(maxWidth: 450),
-            mainAxisSize: .min,
+            child: const ResetEncryptionSheet(isPage: true),
-            crossAxisAlignment: .start,
-            children: [
-              Text(
-                "Enter your recovery key or passphrase below to unlock encrypted events.\nYour passphrase is usually not the same as your password.",
-              ),
-              SizedBox(height: 12),
-              TextFormField(
-                autofocus: true,
-                controller: passphraseController,
-                textInputAction: .done,
-                autovalidateMode: .onUserInteraction,
-                validator: requiredValidator,
-                obscureText: true,
-                decoration: .new(
-                  label: Text("Recovery Key or Passphrase"),
-                  errorText: inputError.value,
-                ),
-                onFieldSubmitted: (_) => verify(),
-                // Don't defocus on submit
-                onEditingComplete: () {},
-              ),
-            ],
           ),
         ),
-        actions: [
+        _ => AlertDialog(
-          TextButton(
+          insetPadding: .symmetric(vertical: 12, horizontal: 32),
-            onPressed: isLoading.value ? null : verify,
+          scrollable: true,
-            child: Text("Verify"),
+          title: Text("Verify"),
+          content: Form(
+            key: formKey.value,
+            child: Column(
+              mainAxisSize: .min,
+              crossAxisAlignment: .start,
+              children: [
+                Text(
+                  "Enter your recovery key or passphrase below to unlock encrypted events.\nYour passphrase is usually not the same as your password.",
+                ),
+                SizedBox(height: 12),
+                TextFormField(
+                  autofocus: true,
+                  controller: passphraseController,
+                  textInputAction: .done,
+                  autovalidateMode: .onUserInteraction,
+                  validator: requiredValidator,
+                  obscureText: true,
+                  decoration: .new(
+                    label: Text("Recovery Key or Passphrase"),
+                    errorText: inputError.value,
+                  ),
+                  onFieldSubmitted: (_) => verify(),
+                  // Don't defocus on submit
+                  onEditingComplete: () {},
+                ),
+              ],
+            ),
           ),
-        ],
+          actions: [
-      ),
+            TextButton(
+              onPressed: () => context.showAdaptiveSheet(
+                (_) => const ResetEncryptionSheet(),
+              ),
+              style: TextButton.styleFrom(
+                foregroundColor: Theme.of(context).colorScheme.error,
+              ),
+              child: Text("Reset Identity"),
+            ),
+            TextButton(
+              onPressed: isLoading.value ? null : verify,
+              child: Text("Verify"),
+            ),
+          ],
+        ),
+      },
     );
   }
 }

lib/widgets/recovery_key_sheet.dart

@@ -0,0 +1,145 @@
+import "dart:async";
+
+import "package:flutter/services.dart";
+import "package:flutter_hooks/flutter_hooks.dart";
+import "package:hooks_riverpod/hooks_riverpod.dart";
+import "package:material_ui/material_ui.dart";
+import "package:nexus/controllers/client.dart";
+import "package:nexus/controllers/client_state.dart";
+import "package:nexus/helpers/launch_helper.dart";
+import "package:nexus/models/gomuks_exception.dart";
+import "package:nexus/models/recovery_key.dart";
+import "package:nexus/widgets/sheet_layout.dart";
+
+/// Shows a newly generated recovery key, and once the user confirms they've
+/// saved it, resets encryption with it. Pops with true if that succeeded.
+class const RecoveryKeySheet(
+  final RecoveryKey recoveryKey, {
+  required final bool isReset,
+  super.key,
+}) extends HookConsumerWidget {
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final saved = useState(false);
+    final isLoading = useState(false);
+    final error = useState<String?>(null);
+    final needsApproval = useState(false);
+    final approvalUrl = useState<Uri?>(null);
+    final colorScheme = Theme.of(context).colorScheme;
+
+    Future<void> reset() async {
+      if (isLoading.value) return;
+      isLoading.value = true;
+      error.value = null;
+      try {
+        await ref
+            .read(ClientController.provider.notifier)
+            .resetEncryption(recoveryKey);
+        if (context.mounted) Navigator.of(context).pop(true);
+      } catch (resetError) {
+        if (resetError case GomuksException(statusCode: 401)) {
+          // Open the approval page straight away the first time.
+          if (!needsApproval.value) {
+            needsApproval.value = true;
+            final homeserver = ref
+                .read(ClientStateController.provider)
+                ?.homeserverUrl;
+            final url = homeserver == null
+                ? null
+                : await ref
+                      .read(ClientController.provider.notifier)
+                      .getCrossSigningResetUrl(.parse(homeserver))
+                      .onError((_, _) => null);
+            if (!context.mounted || url == null) return;
+
+            approvalUrl.value = url;
+            await ref.read(LaunchHelper.provider).launchUrl(url);
+          }
+        } else {
+          error.value = resetError.toString();
+        }
+      } finally {
+        if (context.mounted) isLoading.value = false;
+      }
+    }
+
+    // Approval happens on a web page that can't redirect back, so keep retrying
+    // in the background until it goes through, or the sheet is closed.
+    useEffect(() {
+      if (!needsApproval.value) return null;
+      return Timer.periodic(const .new(seconds: 3), (_) => reset()).cancel;
+    }, [needsApproval.value]);
+
+    return SheetLayout(
+      title: const Text("Save Your Recovery Key"),
+      actions: [
+        TextButton(
+          onPressed: () => Navigator.of(context).pop(false),
+          child: const Text("Cancel"),
+        ),
+        TextButton(
+          onPressed: !saved.value || isLoading.value ? null : reset,
+          style: isReset
+              ? TextButton.styleFrom(foregroundColor: colorScheme.error)
+              : null,
+          child: Text(
+            needsApproval.value
+                ? "Try Again"
+                : isReset
+                ? "Reset"
+                : "Set Up",
+          ),
+        ),
+      ],
+      children: [
+        const Text(
+          "This is your new recovery key. Store it somewhere safe, like a password manager. You'll need it to verify new sessions.",
+        ),
+        Card.filled(
+          child: ListTile(
+            title: SelectableText(
+              recoveryKey.recoveryKey,
+              style: const .new(fontFamily: "bundled-mono"),
+            ),
+            trailing: IconButton(
+              tooltip: "Copy recovery key",
+              onPressed: () =>
+                  Clipboard.setData(.new(text: recoveryKey.recoveryKey)),
+              icon: const Icon(Icons.copy),
+            ),
+          ),
+        ),
+        CheckboxListTile(
+          value: saved.value,
+          onChanged: (value) => saved.value = value ?? false,
+          title: const Text("I've saved my recovery key"),
+        ),
+        AnimatedSize(
+          duration: Durations.medium2,
+          curve: Curves.easeInOut,
+          alignment: .topCenter,
+          child: needsApproval.value
+              ? Column(
+                  crossAxisAlignment: .stretch,
+                  spacing: 8,
+                  children: [
+                    const Text(
+                      "Your homeserver needs you to approve resetting your identity in your account settings. Once you've approved it, come back here and the reset will finish automatically.",
+                    ),
+                    if (approvalUrl.value case final url?)
+                      OutlinedButton.icon(
+                        onPressed: () =>
+                            ref.read(LaunchHelper.provider).launchUrl(url),
+                        icon: const Icon(Icons.open_in_new),
+                        label: const Text("Approve in account settings"),
+                      ),
+                  ],
+                )
+              : const SizedBox(width: .infinity),
+        ),
+        if (error.value case final message?)
+          Text(message, style: .new(color: colorScheme.error)),
+      ],
+    );
+  }
+}

lib/widgets/reset_encryption_sheet.dart

@@ -0,0 +1,153 @@
+import "package:flutter_hooks/flutter_hooks.dart";
+import "package:hooks_riverpod/hooks_riverpod.dart";
+import "package:material_ui/material_ui.dart";
+import "package:nexus/controllers/client.dart";
+import "package:nexus/controllers/client_state.dart";
+import "package:nexus/helpers/extensions/show_adaptive_sheet.dart";
+import "package:nexus/main.dart";
+import "package:nexus/widgets/recovery_key_sheet.dart";
+import "package:nexus/widgets/sheet_layout.dart";
+
+class const ResetEncryptionSheet({
+  /// Whether this is shown as a page rather than in a sheet, in which case it
+  /// can't be cancelled, and is replaced once encryption is set up.
+  final bool isPage = false,
+  super.key,
+}) extends HookConsumerWidget {
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final isReset = ref.watch(
+      ClientStateController.provider.select(
+        (state) => state?.verificationState.hasCrossSigning ?? false,
+      ),
+    );
+
+    final usePassphrase = useState(false);
+    final passphraseController = useTextEditingController();
+    final confirmationController = useTextEditingController();
+    final passphrase = useValueListenable(passphraseController).text;
+    final confirmation = useValueListenable(confirmationController).text;
+    final mismatch = confirmation.isNotEmpty && confirmation != passphrase;
+    final isLoading = useState(false);
+    final error = useState<String?>(null);
+    final colorScheme = Theme.of(context).colorScheme;
+
+    return SheetLayout(
+      title: Text(isReset ? "Reset Encryption Identity" : "Set Up Encryption"),
+      actions: [
+        if (!isPage)
+          TextButton(
+            onPressed: Navigator.of(context).pop,
+            child: const Text("Cancel"),
+          ),
+        TextButton(
+          onPressed:
+              isLoading.value ||
+                  (usePassphrase.value &&
+                      (passphrase.isEmpty || passphrase != confirmation))
+              ? null
+              : () async {
+                  isLoading.value = true;
+                  error.value = null;
+                  try {
+                    final recoveryKey = await ref
+                        .read(ClientController.provider.notifier)
+                        .generateRecoveryKey(
+                          passphrase: usePassphrase.value ? passphrase : "",
+                        );
+                    if (!context.mounted) return;
+
+                    final done = await context.showAdaptiveSheet<bool>(
+                      (_) => RecoveryKeySheet(recoveryKey, isReset: isReset),
+                    );
+                    if (done != true) return;
+                    if (context.mounted && !isPage) Navigator.of(context).pop();
+
+                    // Shown from the root navigator, because on the verify page,
+                    // this is replaced by the chat once the session is verified.
+                    navigatorKey.currentContext?.showAdaptiveSheet(
+                      (context) => SheetLayout(
+                        title: Text(
+                          isReset ? "Identity Reset" : "Encryption Set Up",
+                        ),
+                        actions: [
+                          TextButton(
+                            onPressed: Navigator.of(context).pop,
+                            child: const Text("Done"),
+                          ),
+                        ],
+                        children: [
+                          Text(
+                            isReset
+                                ? "Your encryption identity has been reset, and this session is verified. You'll need to verify your other sessions again."
+                                : "Encryption is set up, and this session is verified. Use your recovery key to verify your other sessions.",
+                          ),
+                        ],
+                      ),
+                    );
+                  } catch (generateError) {
+                    error.value = generateError.toString();
+                  } finally {
+                    if (context.mounted) isLoading.value = false;
+                  }
+                },
+          child: Text(isReset ? "Continue" : "Set Up"),
+        ),
+      ],
+      children: [
+        Text(
+          isReset
+              ? "This replaces your encryption identity with a new one. Your other sessions will need to be verified again, and any messages you can't currently decrypt may become unreadable."
+              : "Set up encryption so you can verify your other sessions, and get back your encrypted messages if you lose access to this one.",
+        ),
+        Column(
+          children: [
+            SwitchListTile(
+              secondary: const Icon(Icons.password),
+              title: const Text("Use a passphrase"),
+              subtitle: const Text("Optional, as well as your recovery key"),
+              value: usePassphrase.value,
+              onChanged: (value) => usePassphrase.value = value,
+            ),
+            AnimatedSize(
+              duration: Durations.medium2,
+              curve: Curves.easeInOut,
+              alignment: .topCenter,
+              child: usePassphrase.value
+                  ? Padding(
+                      padding: const .only(top: 12),
+                      child: Column(
+                        crossAxisAlignment: .stretch,
+                        spacing: 12,
+                        children: [
+                          const Text(
+                            "Your passphrase can be used to gain access to your E2EE messages, so make it long and unique. Your passphrase should ideally not be the same as your password.",
+                          ),
+                          TextField(
+                            controller: passphraseController,
+                            obscureText: true,
+                            decoration: const .new(labelText: "Passphrase"),
+                          ),
+                          TextField(
+                            controller: confirmationController,
+                            obscureText: true,
+                            decoration: .new(
+                              labelText: "Confirm passphrase",
+                              errorText: mismatch
+                                  ? "Passphrases don't match"
+                                  : null,
+                            ),
+                          ),
+                        ],
+                      ),
+                    )
+                  : const SizedBox(width: .infinity),
+            ),
+          ],
+        ),
+        if (error.value case final message?)
+          Text(message, style: .new(color: colorScheme.error)),
+      ],
+    );
+  }
+}