How does the flutter_secure_storage package let you securely store sensitive data, such as an authentication token, on a user's device using each platform's own native secure storage mechanism?

The flutter_secure_storage package provides a consistent, unified Flutter interface for securely storing small pieces of sensitive data by relying on each platform's own dedicated native secure storage mechanism underneath, specifically the Keychain on iOS and the Keystore backed EncryptedSharedPreferences on Android, both of which provide genuinely much stronger security guarantees than simply storing that same sensitive data as plain, readable text using a regular, non secure storage mechanism like SharedPreferences.

final storage = FlutterSecureStorage();
await storage.write(key: 'auth_token', value: token);
final savedToken = await storage.read(key: 'auth_token');