Security Features with fasq_hooks

fasq_hooks supports all FASQ security features through QueryClient configuration, enabling secure data handling in your hooks-based applications.

Overview

Security features in fasq_hooks include:

Secure cache entries with automatic cleanup
Encrypted persistence for sensitive data
Input validation preventing injection attacks
Platform-specific secure key storage

Secure Queries with useQuery

Mark sensitive data to prevent persistence and enable automatic cleanup:


class SecureDataWidget extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final client = context.queryClient;
 
    final secureQuery = useQuery<String>(
      'auth-token',
      () => api.getAuthToken(),
      options: QueryOptions(
        isSecure: true,                    // Mark as secure
        maxAge: Duration(minutes: 15),     // Required TTL
        staleTime: Duration(minutes: 5),
      ),
      client: client,                      // Use configured client
    );
 
    if (secureQuery.isLoading) return CircularProgressIndicator();
    if (secureQuery.hasError) return Text('Error: ${secureQuery.error}');
 
    // Secure data never persisted, cleared on app background
    return Text('Token: ${secureQuery.data}');
  }
}

Security Benefits

Never persisted to disk - Secure entries are memory-only
Automatic cleanup - Cleared on app background/termination
Strict TTL enforcement - Expired secure entries are immediately removed
Not exposed in DevTools - Secure data is hidden from debugging tools

Secure Mutations with useMutation

Handle sensitive mutations with security features:


class SecureMutationWidget extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final client = context.queryClient;
 
    final mutation = useMutation<String, String>(
      mutationFn: (data) => api.secureMutation(data),
      options: MutationOptions(
        queueWhenOffline: true,
        maxRetries: 3,
      ),
      client: client,                      // Use configured client
    );
 
    return ElevatedButton(
      onPressed: mutation.isLoading
          ? null
          : () => mutation.mutate('secure-data'),
      child: mutation.isLoading
          ? CircularProgressIndicator()
          : Text('Secure Mutation'),
    );
  }
}

Global Security Configuration

Configure security features globally using QueryClientProvider:


final secureClient = QueryClient(
  config: const CacheConfig(
    defaultStaleTime: Duration(minutes: 5),
    defaultCacheTime: Duration(minutes: 10),
  ),
  persistenceOptions: const PersistenceOptions(enabled: true),
);
 
QueryClientProvider(
  client: secureClient,
  child: const MaterialApp(
    home: MyApp(),
  ),
);

Accessing Configured Client

Use the configured QueryClient in your hooks:


class MyWidget extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final client = context.queryClient;
 
    // Use configured client in hooks
    final secureQuery = useQuery<String>(
      'secure-data',
      () => fetchSecureData(),
      options: QueryOptions(
        isSecure: true,
        maxAge: Duration(minutes: 30),
      ),
      client: client,
    );
 
    final mutation = useMutation<String, String>(
      mutationFn: (data) => secureMutation(data),
      client: client,
    );
 
    return Column(
      children: [
        Text('Data: ${secureQuery.data}'),
        ElevatedButton(
          onPressed: () => mutation.mutate('data'),
          child: Text('Mutate'),
        ),
      ],
    );
  }
}

Complete Security Example

Here’s a complete example showing security features in a hooks-based app:


class SecureApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final secureClient = QueryClient(
      config: const CacheConfig(
        defaultStaleTime: Duration(minutes: 5),
        defaultCacheTime: Duration(minutes: 10),
      ),
      persistenceOptions: const PersistenceOptions(enabled: true),
    );
 
    return QueryClientProvider(
      client: secureClient,
      child: const MaterialApp(
        home: SecureHomeScreen(),
      ),
    );
  }
}
 
class SecureHomeScreen extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final client = context.queryClient;
 
    // Secure authentication token
    final authToken = useQuery<String>(
      'auth-token',
      () => api.getAuthToken(),
      options: QueryOptions(
        isSecure: true,
        maxAge: Duration(minutes: 15),
        staleTime: Duration(minutes: 5),
      ),
      client: client,
    );
 
    // Secure user profile
    final userProfile = useQuery<User>(
      'user-profile',
      () => api.getUserProfile(),
      options: QueryOptions(
        isSecure: true,
        maxAge: Duration(minutes: 30),
        staleTime: Duration(minutes: 10),
      ),
      client: client,
    );
 
    // Secure mutation for updating profile
    final updateProfile = useMutation<User, User>(
      mutationFn: (user) => api.updateUserProfile(user),
      options: MutationOptions(
        queueWhenOffline: true,
        maxRetries: 3,
        onSuccess: (user) {
          // Invalidate user profile query
          client.invalidateQuery('user-profile');
        },
      ),
      client: client,
    );
 
    return Scaffold(
      appBar: AppBar(title: Text('Secure App')),
      body: Column(
        children: [
          // Display auth token
          if (authToken.isLoading)
            CircularProgressIndicator()
          else if (authToken.hasError)
            Text('Error: ${authToken.error}')
          else
            Text('Token: ${authToken.data}'),
 
          SizedBox(height: 20),
 
          // Display user profile
          if (userProfile.isLoading)
            CircularProgressIndicator()
          else if (userProfile.hasError)
            Text('Error: ${userProfile.error}')
          else
            Text('User: ${userProfile.data?.name}'),
 
          SizedBox(height: 20),
 
          // Update profile button
          ElevatedButton(
            onPressed: updateProfile.isLoading
                ? null
                : () => updateProfile.mutate(
                      User(name: 'Updated Name'),
                    ),
            child: updateProfile.isLoading
                ? CircularProgressIndicator()
                : Text('Update Profile'),
          ),
        ],
      ),
    );
  }
}

Custom Security Hooks

Create custom hooks for common security patterns:


// Custom hook for secure authentication
QueryState<String> useSecureAuth() {
  final client = useQueryClient();
 
  return useQuery<String>(
    'auth-token',
    () => api.getAuthToken(),
    options: QueryOptions(
      isSecure: true,
      maxAge: Duration(minutes: 15),
      staleTime: Duration(minutes: 5),
    ),
    client: client,
  );
}
 
// Custom hook for secure user profile
QueryState<User> useSecureUserProfile() {
  final client = useQueryClient();
 
  return useQuery<User>(
    'user-profile',
    () => api.getUserProfile(),
    options: QueryOptions(
      isSecure: true,
      maxAge: Duration(minutes: 30),
      staleTime: Duration(minutes: 10),
    ),
    client: client,
  );
}
 
// Custom hook for secure profile update
MutationState<User> useSecureProfileUpdate() {
  final client = useQueryClient();
 
  return useMutation<User, User>(
    mutationFn: (user) => api.updateUserProfile(user),
    options: MutationOptions(
      queueWhenOffline: true,
      maxRetries: 3,
      onSuccess: (user) {
        client.invalidateQuery('user-profile');
      },
    ),
    client: client,
  );
}
 
// Usage in widgets
class MyWidget extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final auth = useSecureAuth();
    final profile = useSecureUserProfile();
    final updateProfile = useSecureProfileUpdate();
 
    return Column(
      children: [
        Text('Token: ${auth.data}'),
        Text('User: ${profile.data?.name}'),
        ElevatedButton(
          onPressed: () => updateProfile.mutate(User(name: 'New Name')),
          child: Text('Update'),
        ),
      ],
    );
  }
}

Security Best Practices

1. Always Use Configured Client


// Good - Use configured client
final client = useQueryClient();
final query = useQuery<String>(
  'secure-data',
  () => fetchData(),
  client: client,
)
 
// Bad - Using default client without security config
final query = useQuery<String>(
  'secure-data',
  () => fetchData(),
  // Missing client parameter
)

2. Mark Sensitive Data as Secure


// Good - Sensitive data marked as secure
QueryOptions(
  isSecure: true,
  maxAge: Duration(minutes: 15),
)
 
// Bad - Sensitive data not marked as secure
QueryOptions(
  isSecure: false, // Sensitive data could be persisted
)

3. Use Appropriate TTL Values


// Good - Short TTL for sensitive data
QueryOptions(
  isSecure: true,
  maxAge: Duration(minutes: 15), // Short-lived tokens
)
 
// Bad - Too long TTL for sensitive data
QueryOptions(
  isSecure: true,
  maxAge: Duration(hours: 24), // Too long for sensitive data
)

4. Handle Security Errors Gracefully


class SecureWidget extends HookWidget {
  @override
  Widget build(BuildContext context) {
    final client = useQueryClient();
 
    final query = useQuery<String>(
      'secure-data',
      () => fetchData(),
      client: client,
    );
 
    // Handle security-related errors
    useEffect(() {
      if (query.hasError) {
        if (query.error.toString().contains('validation')) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(content: Text('Invalid input detected')),
          );
        }
      }
      return null;
    }, [query.hasError]);
 
    return Text('${query.data}');
  }
}

Migration Guide

Enabling Security in Existing Apps

Add the security package using the Flutter CLI:


flutter pub add fasq_security

[!TIP] This package integrates with the Fasq core and the hooks adapter.

Wrap your app with QueryClientProvider:


QueryClientProvider(
  config: CacheConfig(
    defaultStaleTime: Duration(minutes: 5),
    defaultCacheTime: Duration(minutes: 10),
  ),
  persistenceOptions: PersistenceOptions(
    enabled: true,
    encryptionKey: 'your-encryption-key',
  ),
  child: MaterialApp(
    home: MyApp(),
  ),
)

Update existing useQuery calls:


// Before
final query = useQuery<String>(
  'auth-token',
  () => api.getAuthToken(),
)
 
// After
final client = useQueryClient();
final query = useQuery<String>(
  'auth-token',
  () => api.getAuthToken(),
  options: QueryOptions(
    isSecure: true,
    maxAge: Duration(minutes: 15),
  ),
  client: client,
)

Update existing useMutation calls:


// Before
final mutation = useMutation<String, String>(
  mutationFn: (data) => api.mutate(data),
)
 
// After
final client = useQueryClient();
final mutation = useMutation<String, String>(
  mutationFn: (data) => api.mutate(data),
  client: client,
)

Troubleshooting

Common Issues

Client not found:

Ensure QueryClientProvider wraps your app
Use useQueryClient() hook to access the configured client

Security validation errors:

Check query key format (alphanumeric, colon, hyphen, underscore only)
Ensure durations are non-negative
Verify cache data doesn’t contain functions

Performance issues:

Large data (>50KB) is automatically encrypted in isolates
Consider reducing cache size for better performance
Use appropriate TTL values to prevent memory bloat

Error Messages

Error	Cause	Solution
”Query key must contain only alphanumeric, colon, hyphen, underscore”	Invalid query key format	Use valid characters only
”Secure queries must specify maxAge for TTL enforcement”	Missing maxAge for secure query	Add maxAge to QueryOptions
”staleTime must be non-negative”	Negative duration	Use positive or zero duration
”Cache data cannot be a function or closure”	Function in cache data	Remove functions from cached data