Add reusable two-factor verification for login and money operations (#32)

frontend/app/lib/auth/feedback.dart

@@ -23,6 +23,9 @@ class AuthFeedback extends StatelessWidget {
             AuthError.emailInUse => l.authEmailInUse,
             AuthError.unavailable => l.authUnavailable,
             AuthError.unexpected => l.authUnexpected,
+            AuthError.factorLocked => l.factorLocked,
+            AuthError.factorCooldown => l.factorWait,
+            AuthError.factorRequired => l.factorRequired,
           };
     return Semantics(
       liveRegion: true,

frontend/app/lib/auth/form.dart

@@ -9,6 +9,7 @@ import 'package:sxchnge_analytics/sxchnge_analytics.dart';
 import 'package:sxchnge_auth/sxchnge_auth.dart';
 
 import '../routing/routes.dart';
+import '../security/challenge.dart';
 import 'feedback.dart';
 import 'validation.dart';
 
@@ -96,11 +97,34 @@ class _AuthFormState extends State<AuthForm> {
       _confirmation.clear();
       context.goNamed(AppRoutes.verificationSent, extra: email);
     } else {
-      await context.read<LoginProvider>().login(
+      final login = context.read<LoginProvider>();
+      await login.login(
         email: _email.text,
         password: _password.text,
         locale: locale,
       );
+      if (!mounted || _signUp) return;
+      final challenge = login.state.result?.challenge;
+      if (challenge != null) {
+        _password.clear();
+        final grant = await verifyFactor(
+          context,
+          challenge: challenge,
+          service: context.read<TwoFactorService>(),
+          recorder: context.read<JourneyRecorder>(),
+          journey: JourneyKind.login,
+        );
+        if (!mounted || _signUp) return;
+        if (grant == null) {
+          login.reset();
+          context.read<JourneyRecorder>().abandon(JourneyExit.navigation);
+          return;
+        }
+        await login.complete(challenge, grant);
+        if (mounted && login.state.status == AuthStatus.success) {
+          context.go('/accounts');
+        }
+      }
     }
   }
 

frontend/app/lib/generated/i18n/app_localizations.dart

@@ -1465,6 +1465,174 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'Make another transaction'**
   String get wAnother;
+
+  /// No description provided for @factorTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'One more check.'**
+  String get factorTitle;
+
+  /// No description provided for @factorLogin.
+  ///
+  /// In en, this message translates to:
+  /// **'Confirm it’s you to finish signing in.'**
+  String get factorLogin;
+
+  /// No description provided for @factorMoney.
+  ///
+  /// In en, this message translates to:
+  /// **'Confirm this transaction. No money moves before confirmation.'**
+  String get factorMoney;
+
+  /// No description provided for @factorEnableHelp.
+  ///
+  /// In en, this message translates to:
+  /// **'Confirm to turn on two-factor verification for sign-in and money operations.'**
+  String get factorEnableHelp;
+
+  /// No description provided for @factorDisableHelp.
+  ///
+  /// In en, this message translates to:
+  /// **'Confirm to turn off two-factor verification. Sign-in and money operations will no longer ask for a second code.'**
+  String get factorDisableHelp;
+
+  /// No description provided for @factorEmail.
+  ///
+  /// In en, this message translates to:
+  /// **'Enter the six-digit code sent to your email.'**
+  String get factorEmail;
+
+  /// No description provided for @factorAuthenticator.
+  ///
+  /// In en, this message translates to:
+  /// **'Enter the current six-digit code from your authenticator app.'**
+  String get factorAuthenticator;
+
+  /// No description provided for @factorCode.
+  ///
+  /// In en, this message translates to:
+  /// **'Verification code'**
+  String get factorCode;
+
+  /// No description provided for @factorConfirm.
+  ///
+  /// In en, this message translates to:
+  /// **'Verify and continue'**
+  String get factorConfirm;
+
+  /// No description provided for @factorResend.
+  ///
+  /// In en, this message translates to:
+  /// **'Send a new code'**
+  String get factorResend;
+
+  /// No description provided for @factorHelp.
+  ///
+  /// In en, this message translates to:
+  /// **'Check your inbox and spam folder. A new code replaces the previous one.'**
+  String get factorHelp;
+
+  /// No description provided for @factorAppHelp.
+  ///
+  /// In en, this message translates to:
+  /// **'Use the current code. If you cannot access your authenticator, cancel this action.'**
+  String get factorAppHelp;
+
+  /// No description provided for @factorInvalid.
+  ///
+  /// In en, this message translates to:
+  /// **'That code is not valid. Check all six digits and try again.'**
+  String get factorInvalid;
+
+  /// No description provided for @factorExpired.
+  ///
+  /// In en, this message translates to:
+  /// **'This verification has expired. Request a new code or return to start again.'**
+  String get factorExpired;
+
+  /// No description provided for @factorLocked.
+  ///
+  /// In en, this message translates to:
+  /// **'Too many incorrect attempts. Wait five minutes, then start verification again.'**
+  String get factorLocked;
+
+  /// No description provided for @factorWait.
+  ///
+  /// In en, this message translates to:
+  /// **'Please wait before requesting another code.'**
+  String get factorWait;
+
+  /// No description provided for @factorRequired.
+  ///
+  /// In en, this message translates to:
+  /// **'Verification is needed again. Please confirm this action once more.'**
+  String get factorRequired;
+
+  /// No description provided for @factorUnavailable.
+  ///
+  /// In en, this message translates to:
+  /// **'Could not complete verification. Try again or cancel this action.'**
+  String get factorUnavailable;
+
+  /// No description provided for @factorCooldown.
+  ///
+  /// In en, this message translates to:
+  /// **'Send a new code in {seconds}s'**
+  String factorCooldown(int seconds);
+
+  /// No description provided for @factorSettings.
+  ///
+  /// In en, this message translates to:
+  /// **'Two-factor verification'**
+  String get factorSettings;
+
+  /// No description provided for @factorSettingsHelp.
+  ///
+  /// In en, this message translates to:
+  /// **'Add a verification code when you sign in, top up, exchange or pay out.'**
+  String get factorSettingsHelp;
+
+  /// No description provided for @factorOn.
+  ///
+  /// In en, this message translates to:
+  /// **'On'**
+  String get factorOn;
+
+  /// No description provided for @factorOff.
+  ///
+  /// In en, this message translates to:
+  /// **'Off'**
+  String get factorOff;
+
+  /// No description provided for @factorEnable.
+  ///
+  /// In en, this message translates to:
+  /// **'Turn on'**
+  String get factorEnable;
+
+  /// No description provided for @factorDisable.
+  ///
+  /// In en, this message translates to:
+  /// **'Turn off'**
+  String get factorDisable;
+
+  /// No description provided for @factorEmailMethod.
+  ///
+  /// In en, this message translates to:
+  /// **'Email code'**
+  String get factorEmailMethod;
+
+  /// No description provided for @factorAppMethod.
+  ///
+  /// In en, this message translates to:
+  /// **'Authenticator app'**
+  String get factorAppMethod;
+
+  /// No description provided for @factorAppExpired.
+  ///
+  /// In en, this message translates to:
+  /// **'This verification has expired. Return and start again.'**
+  String get factorAppExpired;
 }
 
 class _AppLocalizationsDelegate

frontend/app/lib/generated/i18n/app_localizations_en.dart

@@ -758,4 +758,103 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get wAnother => 'Make another transaction';
+
+  @override
+  String get factorTitle => 'One more check.';
+
+  @override
+  String get factorLogin => 'Confirm it’s you to finish signing in.';
+
+  @override
+  String get factorMoney =>
+      'Confirm this transaction. No money moves before confirmation.';
+
+  @override
+  String get factorEnableHelp =>
+      'Confirm to turn on two-factor verification for sign-in and money operations.';
+
+  @override
+  String get factorDisableHelp =>
+      'Confirm to turn off two-factor verification. Sign-in and money operations will no longer ask for a second code.';
+
+  @override
+  String get factorEmail => 'Enter the six-digit code sent to your email.';
+
+  @override
+  String get factorAuthenticator =>
+      'Enter the current six-digit code from your authenticator app.';
+
+  @override
+  String get factorCode => 'Verification code';
+
+  @override
+  String get factorConfirm => 'Verify and continue';
+
+  @override
+  String get factorResend => 'Send a new code';
+
+  @override
+  String get factorHelp =>
+      'Check your inbox and spam folder. A new code replaces the previous one.';
+
+  @override
+  String get factorAppHelp =>
+      'Use the current code. If you cannot access your authenticator, cancel this action.';
+
+  @override
+  String get factorInvalid =>
+      'That code is not valid. Check all six digits and try again.';
+
+  @override
+  String get factorExpired =>
+      'This verification has expired. Request a new code or return to start again.';
+
+  @override
+  String get factorLocked =>
+      'Too many incorrect attempts. Wait five minutes, then start verification again.';
+
+  @override
+  String get factorWait => 'Please wait before requesting another code.';
+
+  @override
+  String get factorRequired =>
+      'Verification is needed again. Please confirm this action once more.';
+
+  @override
+  String get factorUnavailable =>
+      'Could not complete verification. Try again or cancel this action.';
+
+  @override
+  String factorCooldown(int seconds) {
+    return 'Send a new code in ${seconds}s';
+  }
+
+  @override
+  String get factorSettings => 'Two-factor verification';
+
+  @override
+  String get factorSettingsHelp =>
+      'Add a verification code when you sign in, top up, exchange or pay out.';
+
+  @override
+  String get factorOn => 'On';
+
+  @override
+  String get factorOff => 'Off';
+
+  @override
+  String get factorEnable => 'Turn on';
+
+  @override
+  String get factorDisable => 'Turn off';
+
+  @override
+  String get factorEmailMethod => 'Email code';
+
+  @override
+  String get factorAppMethod => 'Authenticator app';
+
+  @override
+  String get factorAppExpired =>
+      'This verification has expired. Return and start again.';
 }

frontend/app/lib/generated/i18n/app_localizations_ru.dart

@@ -755,4 +755,103 @@ class AppLocalizationsRu extends AppLocalizations {
 
   @override
   String get wAnother => 'Создать новую операцию';
+
+  @override
+  String get factorTitle => 'Ещё одна проверка.';
+
+  @override
+  String get factorLogin => 'Подтвердите, что это вы, чтобы завершить вход.';
+
+  @override
+  String get factorMoney =>
+      'Подтвердите эту операцию. До подтверждения деньги не переводятся.';
+
+  @override
+  String get factorEnableHelp =>
+      'Подтвердите включение двухфакторной проверки для входа и операций с деньгами.';
+
+  @override
+  String get factorDisableHelp =>
+      'Подтвердите отключение двухфакторной проверки. Для входа и операций больше не потребуется второй код.';
+
+  @override
+  String get factorEmail => 'Введите шестизначный код из письма.';
+
+  @override
+  String get factorAuthenticator =>
+      'Введите текущий шестизначный код из приложения-аутентификатора.';
+
+  @override
+  String get factorCode => 'Код подтверждения';
+
+  @override
+  String get factorConfirm => 'Подтвердить и продолжить';
+
+  @override
+  String get factorResend => 'Отправить новый код';
+
+  @override
+  String get factorHelp =>
+      'Проверьте входящие и папку «Спам». Новый код заменяет предыдущий.';
+
+  @override
+  String get factorAppHelp =>
+      'Используйте текущий код. Если приложение недоступно, отмените это действие.';
+
+  @override
+  String get factorInvalid =>
+      'Неверный код. Проверьте все шесть цифр и попробуйте ещё раз.';
+
+  @override
+  String get factorExpired =>
+      'Срок проверки истёк. Запросите новый код или вернитесь и начните снова.';
+
+  @override
+  String get factorLocked =>
+      'Слишком много неверных попыток. Подождите пять минут и начните проверку снова.';
+
+  @override
+  String get factorWait => 'Подождите перед повторным запросом кода.';
+
+  @override
+  String get factorRequired =>
+      'Нужна повторная проверка. Подтвердите это действие ещё раз.';
+
+  @override
+  String get factorUnavailable =>
+      'Не удалось завершить проверку. Повторите попытку или отмените действие.';
+
+  @override
+  String factorCooldown(int seconds) {
+    return 'Новый код через $seconds с';
+  }
+
+  @override
+  String get factorSettings => 'Двухфакторная проверка';
+
+  @override
+  String get factorSettingsHelp =>
+      'Подтверждайте кодом вход, пополнение, обмен и вывод средств.';
+
+  @override
+  String get factorOn => 'Включена';
+
+  @override
+  String get factorOff => 'Выключена';
+
+  @override
+  String get factorEnable => 'Включить';
+
+  @override
+  String get factorDisable => 'Выключить';
+
+  @override
+  String get factorEmailMethod => 'Код из письма';
+
+  @override
+  String get factorAppMethod => 'Приложение-аутентификатор';
+
+  @override
+  String get factorAppExpired =>
+      'Срок проверки истёк. Вернитесь и начните снова.';
 }

frontend/app/lib/l10n/en.arb

@@ -227,5 +227,40 @@
   "wLimitsScope": "Outgoing activity · EUR equivalent",
   "wPendingHint": "Refresh to check the latest status. You can keep using your other accounts.",
   "wFundsHeading": "Where is my money?",
-  "wAnother": "Make another transaction"
+  "wAnother": "Make another transaction",
+  "factorTitle": "One more check.",
+  "factorLogin": "Confirm it’s you to finish signing in.",
+  "factorMoney": "Confirm this transaction. No money moves before confirmation.",
+  "factorEnableHelp": "Confirm to turn on two-factor verification for sign-in and money operations.",
+  "factorDisableHelp": "Confirm to turn off two-factor verification. Sign-in and money operations will no longer ask for a second code.",
+  "factorEmail": "Enter the six-digit code sent to your email.",
+  "factorAuthenticator": "Enter the current six-digit code from your authenticator app.",
+  "factorCode": "Verification code",
+  "factorConfirm": "Verify and continue",
+  "factorResend": "Send a new code",
+  "factorHelp": "Check your inbox and spam folder. A new code replaces the previous one.",
+  "factorAppHelp": "Use the current code. If you cannot access your authenticator, cancel this action.",
+  "factorInvalid": "That code is not valid. Check all six digits and try again.",
+  "factorExpired": "This verification has expired. Request a new code or return to start again.",
+  "factorLocked": "Too many incorrect attempts. Wait five minutes, then start verification again.",
+  "factorWait": "Please wait before requesting another code.",
+  "factorRequired": "Verification is needed again. Please confirm this action once more.",
+  "factorUnavailable": "Could not complete verification. Try again or cancel this action.",
+  "factorCooldown": "Send a new code in {seconds}s",
+  "factorSettings": "Two-factor verification",
+  "factorSettingsHelp": "Add a verification code when you sign in, top up, exchange or pay out.",
+  "factorOn": "On",
+  "factorOff": "Off",
+  "factorEnable": "Turn on",
+  "factorDisable": "Turn off",
+  "@factorCooldown": {
+    "placeholders": {
+      "seconds": {
+        "type": "int"
+      }
+    }
+  },
+  "factorEmailMethod": "Email code",
+  "factorAppMethod": "Authenticator app",
+  "factorAppExpired": "This verification has expired. Return and start again."
 }

frontend/app/lib/l10n/ru.arb

@@ -227,5 +227,40 @@
   "wLimitsScope": "Исходящие операции · эквивалент в EUR",
   "wPendingHint": "Обновите, чтобы узнать текущий статус. Остальными счетами можно пользоваться.",
   "wFundsHeading": "Где мои деньги?",
-  "wAnother": "Создать новую операцию"
+  "wAnother": "Создать новую операцию",
+  "factorTitle": "Ещё одна проверка.",
+  "factorLogin": "Подтвердите, что это вы, чтобы завершить вход.",
+  "factorMoney": "Подтвердите эту операцию. До подтверждения деньги не переводятся.",
+  "factorEnableHelp": "Подтвердите включение двухфакторной проверки для входа и операций с деньгами.",
+  "factorDisableHelp": "Подтвердите отключение двухфакторной проверки. Для входа и операций больше не потребуется второй код.",
+  "factorEmail": "Введите шестизначный код из письма.",
+  "factorAuthenticator": "Введите текущий шестизначный код из приложения-аутентификатора.",
+  "factorCode": "Код подтверждения",
+  "factorConfirm": "Подтвердить и продолжить",
+  "factorResend": "Отправить новый код",
+  "factorHelp": "Проверьте входящие и папку «Спам». Новый код заменяет предыдущий.",
+  "factorAppHelp": "Используйте текущий код. Если приложение недоступно, отмените это действие.",
+  "factorInvalid": "Неверный код. Проверьте все шесть цифр и попробуйте ещё раз.",
+  "factorExpired": "Срок проверки истёк. Запросите новый код или вернитесь и начните снова.",
+  "factorLocked": "Слишком много неверных попыток. Подождите пять минут и начните проверку снова.",
+  "factorWait": "Подождите перед повторным запросом кода.",
+  "factorRequired": "Нужна повторная проверка. Подтвердите это действие ещё раз.",
+  "factorUnavailable": "Не удалось завершить проверку. Повторите попытку или отмените действие.",
+  "factorCooldown": "Новый код через {seconds} с",
+  "factorSettings": "Двухфакторная проверка",
+  "factorSettingsHelp": "Подтверждайте кодом вход, пополнение, обмен и вывод средств.",
+  "factorOn": "Включена",
+  "factorOff": "Выключена",
+  "factorEnable": "Включить",
+  "factorDisable": "Выключить",
+  "@factorCooldown": {
+    "placeholders": {
+      "seconds": {
+        "type": "int"
+      }
+    }
+  },
+  "factorEmailMethod": "Код из письма",
+  "factorAppMethod": "Приложение-аутентификатор",
+  "factorAppExpired": "Срок проверки истёк. Вернитесь и начните снова."
 }

frontend/app/lib/main.dart

@@ -31,6 +31,7 @@ class SxchngeApp extends StatefulWidget {
     this.identityService,
     this.limitsService,
     this.walletService,
+    this.twoFactorService,
     this.photoService = const FilePhotoService(),
     this.loginService = const DummyLoginService(),
     this.signupService = const DummySignupService(),
@@ -41,6 +42,7 @@ class SxchngeApp extends StatefulWidget {
   final IdentityService? identityService;
   final LimitsService? limitsService;
   final WalletService? walletService;
+  final TwoFactorService? twoFactorService;
   final PhotoService photoService;
   final LoginService loginService;
   final SignupService signupService;
@@ -54,11 +56,21 @@ class _SxchngeAppState extends State<SxchngeApp> {
   late final _locale = widget.localeProvider ?? LocaleProvider();
 
   late final _analytics = widget.analyticsService ?? DummyAnalyticsService();
+  late final _factors = widget.twoFactorService ?? DummyTwoFactorService();
+  late final _security = SecurityProvider(_factors, _analytics);
   late final _identity = widget.identityService ?? DummyIdentityService();
   late final _walletService =
       widget.walletService ??
-      DummyWalletService(_identity, initialLocale: _locale.locale.languageCode);
-  late final _wallet = WalletProvider(_walletService, _analytics);
+      DummyWalletService(
+        _identity,
+        initialLocale: _locale.locale.languageCode,
+        factors: _factors,
+      );
+  late final _wallet = WalletProvider(
+    _walletService,
+    _analytics,
+    factors: _factors,
+  );
   late final _limits =
       widget.limitsService ??
       (_walletService is DummyWalletService
@@ -67,7 +79,7 @@ class _SxchngeAppState extends State<SxchngeApp> {
   late final _journeys = JourneyRecorder(_analytics);
   late final _services = InstrumentedAuthServices(
     recorder: _journeys,
-    loginService: widget.loginService,
+    loginService: GuardedLoginService(widget.loginService, _factors),
     signupService: widget.signupService,
     verificationService: widget.verificationService,
   );
@@ -83,7 +95,7 @@ class _SxchngeAppState extends State<SxchngeApp> {
 
   void _routeChanged() {
     final path = _router.routeInformationProvider.value.uri.path;
-    if (path == '/' && _previousPath != '/') {
+    if (path == '/' && _previousPath != '/' && _previousPath != '/two-factor') {
       _journeys.abandon(JourneyExit.navigation);
     }
     _previousPath = path;
@@ -95,6 +107,7 @@ class _SxchngeAppState extends State<SxchngeApp> {
     _router.dispose();
     _journeys.dispose();
     _wallet.dispose();
+    _security.dispose();
     _locale.dispose();
     super.dispose();
   }
@@ -103,6 +116,8 @@ class _SxchngeAppState extends State<SxchngeApp> {
   Widget build(BuildContext context) => MultiProvider(
     providers: [
       ChangeNotifierProvider.value(value: _wallet),
+      ChangeNotifierProvider.value(value: _security),
+      Provider<TwoFactorService>.value(value: _factors),
       Provider<JourneyRecorder>.value(value: _journeys),
       Provider<AnalyticsService>.value(value: _analytics),
       Provider<IdentityService>.value(value: _identity),

frontend/app/lib/routing/router.dart

@@ -8,6 +8,7 @@ import 'package:sxchnge_wallet/sxchnge_wallet.dart';
 
 import '../auth/page.dart';
 import '../kyc/page.dart';
+import '../security/challenge.dart';
 import '../verification/page.dart';
 import '../workspace/accounts.dart';
 import '../workspace/activity.dart';
@@ -27,6 +28,16 @@ GoRouter createAppRouter() {
     // Signup email is an in-memory navigation extra, never browser-history data.
     extraCodec: const _TransientExtras(),
     routes: [
+      GoRoute(
+        path: '/two-factor',
+        redirect: (context, state) =>
+            state.extra is FactorRouteRequest ? null : '/',
+        builder: (context, state) =>
+            FactorRoute(request: state.extra as FactorRouteRequest),
+        onExit: (context, state) =>
+            state.extra is! FactorRouteRequest ||
+            !(state.extra as FactorRouteRequest).provider.busy,
+      ),
       ShellRoute(
         builder: (context, state, child) =>
             WorkspaceShell(path: state.uri.path, child: child),

frontend/app/lib/security/challenge.dart

@@ -0,0 +1,116 @@
+import 'package:flutter/material.dart';
+
+import 'package:go_router/go_router.dart';
+
+import 'package:sxchnge_analytics/sxchnge_analytics.dart';
+
+import 'package:sxchnge_auth/sxchnge_auth.dart';
+
+import '../generated/i18n/app_localizations.dart';
+
+class FactorRouteRequest {
+  const FactorRouteRequest(this.provider, this.summary);
+  final TwoFactorProvider provider;
+  final Widget? summary;
+}
+
+Future<FactorGrant?> verifyFactor(
+  BuildContext context, {
+  required FactorChallenge challenge,
+  required TwoFactorService service,
+  required JourneyRecorder recorder,
+  required JourneyKind journey,
+  Widget? summary,
+}) async {
+  final provider = TwoFactorProvider(
+    service,
+    challenge,
+    recorder: recorder,
+    journey: journey,
+  );
+  FactorGrant? result;
+  try {
+    result = await context.push<FactorGrant>(
+      '/two-factor',
+      extra: FactorRouteRequest(provider, summary),
+    );
+    return result;
+  } finally {
+    if (result == null) {
+      final step = recorder.begin(
+        journey,
+        JourneyStep.factorVerification,
+        simulated: service.isSimulated,
+      );
+      recorder.finish(step, cancelled: true, simulated: service.isSimulated);
+    }
+    provider.dispose();
+  }
+}
+
+String factorErrorText(AppLocalizations l, FactorError error) =>
+    switch (error) {
+      FactorError.invalid => l.factorInvalid,
+      FactorError.expired => l.factorExpired,
+      FactorError.locked => l.factorLocked,
+      FactorError.cooldown => l.factorWait,
+      FactorError.required => l.factorRequired,
+      FactorError.unavailable => l.factorUnavailable,
+    };
+
+class FactorRoute extends StatefulWidget {
+  const FactorRoute({super.key, required this.request});
+  final FactorRouteRequest request;
+  @override
+  State<FactorRoute> createState() => _FactorRouteState();
+}
+
+class _FactorRouteState extends State<FactorRoute> {
+  FactorRouteRequest get request => widget.request;
+  @override
+  void dispose() {
+    request.provider.dispose();
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final l = AppLocalizations.of(context)!;
+    final purpose = request.provider.challenge.purpose;
+    final purposeText = switch (purpose) {
+      FactorPurpose.login => l.factorLogin,
+      FactorPurpose.enable => l.factorEnableHelp,
+      FactorPurpose.disable => l.factorDisableHelp,
+      _ => l.factorMoney,
+    };
+    final methodText = request.provider.challenge.method == FactorMethod.email
+        ? l.factorEmail
+        : l.factorAuthenticator;
+    return TwoFactorPage(
+      provider: request.provider,
+      summary: request.summary,
+      labels: TwoFactorLabels(
+        title: l.factorTitle,
+        description: '$purposeText $methodText',
+        code: l.factorCode,
+        confirm: l.factorConfirm,
+        cancel: l.wClose,
+        resend: l.factorResend,
+        expired: request.provider.challenge.method == FactorMethod.email
+            ? l.factorExpired
+            : l.factorAppExpired,
+        help: request.provider.challenge.method == FactorMethod.email
+            ? l.factorHelp
+            : l.factorAppHelp,
+        errorText: (error) =>
+            error == FactorError.expired &&
+                request.provider.challenge.method == FactorMethod.authenticator
+            ? l.factorAppExpired
+            : factorErrorText(l, error),
+        cooldownText: (seconds) => l.factorCooldown(seconds),
+      ),
+      onVerified: (grant) => context.pop(grant),
+      onCancel: () => context.pop(),
+    );
+  }
+}

frontend/app/lib/security/settings.dart

@@ -0,0 +1,98 @@
+import 'package:flutter/material.dart';
+
+import 'package:provider/provider.dart';
+
+import 'package:sxchnge_analytics/sxchnge_analytics.dart';
+
+import 'package:sxchnge_auth/sxchnge_auth.dart';
+
+import 'challenge.dart';
+
+import '../generated/i18n/app_localizations.dart';
+
+class SecuritySettings extends StatefulWidget {
+  const SecuritySettings({super.key});
+  @override
+  State<SecuritySettings> createState() => _SecuritySettingsState();
+}
+
+class _SecuritySettingsState extends State<SecuritySettings> {
+  @override
+  void initState() {
+    super.initState();
+    WidgetsBinding.instance.addPostFrameCallback((_) {
+      if (mounted) context.read<SecurityProvider>().refresh();
+    });
+  }
+
+  Future<void> _change(SecurityProvider p, bool enabled) async {
+    final challenge = await p.prepare(enabled);
+    if (!mounted || challenge == null) return;
+    final grant = await verifyFactor(
+      context,
+      challenge: challenge,
+      service: p.service,
+      recorder: p.recorder,
+      journey: JourneyKind.security,
+    );
+    if (mounted && grant != null) await p.apply(enabled, grant);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final p = context.watch<SecurityProvider>();
+    final l = AppLocalizations.of(context)!;
+    final t = Theme.of(context);
+    return Card(
+      child: Padding(
+        padding: const EdgeInsets.all(24),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.stretch,
+          children: [
+            Text(l.factorSettings, style: t.textTheme.titleLarge),
+            const SizedBox(height: 12),
+            Text(l.factorSettingsHelp),
+            const SizedBox(height: 16),
+            if (p.busy) const LinearProgressIndicator(),
+            if (p.data != null) ...[
+              Semantics(
+                liveRegion: true,
+                child: Text(
+                  p.data!.enabled ? l.factorOn : l.factorOff,
+                  key: const ValueKey('two-factor-status'),
+                  style: t.textTheme.titleMedium,
+                ),
+              ),
+              const SizedBox(height: 8),
+              Text(
+                p.data!.method == FactorMethod.email
+                    ? l.factorEmailMethod
+                    : l.factorAppMethod,
+              ),
+              const SizedBox(height: 16),
+              FilledButton.tonal(
+                key: const ValueKey('two-factor-setting'),
+                onPressed: p.busy ? null : () => _change(p, !p.data!.enabled),
+                child: Text(p.data!.enabled ? l.factorDisable : l.factorEnable),
+              ),
+            ],
+            if (p.error != null) ...[
+              const SizedBox(height: 12),
+              Semantics(
+                liveRegion: true,
+                child: Text(
+                  factorErrorText(l, p.error!),
+                  style: TextStyle(color: t.colorScheme.error),
+                ),
+              ),
+              TextButton(
+                onPressed: p.busy ? null : p.refresh,
+                child: Text(l.wRefresh),
+              ),
+            ],
+          ],
+        ),
+      ),
+    );
+  }
+}

frontend/app/lib/workspace/settings.dart

@@ -7,6 +7,7 @@ import 'package:provider/provider.dart';
 import 'package:sxchnge_wallet/sxchnge_wallet.dart';
 
 import '../providers/locale.dart';
+import '../security/settings.dart';
 
 import '../generated/i18n/app_localizations.dart';
 
@@ -105,19 +106,7 @@ class SettingsPage extends StatelessWidget {
                 ),
               ),
               const SizedBox(height: 16),
-              Card(
-                child: Padding(
-                  padding: const EdgeInsets.all(24),
-                  child: Column(
-                    crossAxisAlignment: CrossAxisAlignment.start,
-                    children: [
-                      Text(l.wSecurity, style: t.textTheme.titleLarge),
-                      const SizedBox(height: 12),
-                      Text(l.wSecurityBody),
-                    ],
-                  ),
-                ),
-              ),
+              const SecuritySettings(),
               const SizedBox(height: 20),
               TextButton(
                 onPressed: () => context.go('/'),

frontend/app/lib/workspace/transfer.dart

@@ -6,8 +6,12 @@ import 'package:go_router/go_router.dart';
 
 import 'package:provider/provider.dart';
 
+import 'package:sxchnge_auth/sxchnge_auth.dart';
+
 import 'package:sxchnge_wallet/sxchnge_wallet.dart';
 
+import '../security/challenge.dart';
+
 import 'copy.dart';
 import 'summary.dart';
 
@@ -64,6 +68,25 @@ class TransferPageState extends State<TransferPage> {
     }
   }
 
+  Future<void> _confirm() async {
+    final p = _provider;
+    final challenge = await p.challenge();
+    if (!mounted || p.factorError != null || p.error != null) return;
+    FactorGrant? grant;
+    if (challenge != null) {
+      grant = await verifyFactor(
+        context,
+        challenge: challenge,
+        service: p.wallet.factors!,
+        recorder: p.recorder,
+        journey: p.journey,
+        summary: TransferSummary(quote: p.quote!),
+      );
+      if (!mounted || grant == null) return;
+    }
+    await p.submit(approval: grant);
+  }
+
   Future<bool> allowExit() async {
     if (_provider.result != null) return true;
     if (_provider.busy || _provider.uncertain) return false;
@@ -163,6 +186,17 @@ class TransferPageState extends State<TransferPage> {
                             ),
                           ),
                         ),
+                      if (p.factorError != null)
+                        Padding(
+                          padding: const EdgeInsets.only(bottom: 16),
+                          child: Semantics(
+                            liveRegion: true,
+                            child: Text(
+                              factorErrorText(l, p.factorError!),
+                              style: TextStyle(color: t.colorScheme.error),
+                            ),
+                          ),
+                        ),
                       if (p.noSubmission) Text(l.wNoSubmission),
                       if (p.uncertain) ...[
                         Text(l.wUncertain),
@@ -183,7 +217,7 @@ class TransferPageState extends State<TransferPage> {
                         else
                           FilledButton(
                             key: const ValueKey('transfer-confirm'),
-                            onPressed: p.busy ? null : p.submit,
+                            onPressed: p.busy ? null : _confirm,
                             child: Text(l.wConfirm),
                           ),
                         TextButton(