Email/password login in Firebase - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

What happens when a user tries to sign in with an unregistered email?

Using Firebase Email/Password login, what is the expected behavior if a user attempts to sign in with an email that is not registered?

A Firebase signs in the user anonymously without a password.

B Firebase ignores the request and returns no response.

C Firebase automatically creates a new user with that email.

D Firebase returns an error indicating the user does not exist.

💡 Hint

Think about how Firebase handles sign-in attempts with unknown emails.

Firebase requires users to be registered before signing in. If the email is not found, it returns an error indicating the user does not exist.

❓ security

intermediate

Which Firebase rule protects user data from unauthorized access?

In Firebase Realtime Database or Firestore, which security rule ensures that users can only read and write their own data after email/password login?

A allow read, write: if request.auth.email_verified == false;

B allow read, write: if request.auth != null && request.auth.uid == resource.data.userId;

C allow read, write: if request.time < timestamp.date(2025, 1, 1);

D allow read, write: if request.auth.token.admin == true;

💡 Hint

Consider how to restrict access to only the authenticated user's own data.

This rule checks that the user is authenticated and that their user ID matches the data's userId field, ensuring only owners access their data.

❓ Configuration

advanced

What is the correct Firebase config snippet to enable email/password sign-in?

Which configuration snippet correctly enables email/password sign-in method in Firebase Authentication?

A firebase.auth().enableEmailPassword(true);

B firebase.auth().settings.signInMethod = 'emailPassword';

C In Firebase Console, under Authentication > Sign-in method, enable Email/Password toggle.

D firebase.auth().useDeviceLanguage(); firebase.auth().signInWithEmailAndPassword(email, password);

💡 Hint

Think about where sign-in methods are enabled in Firebase.

Email/password sign-in is enabled via the Firebase Console under Authentication settings, not by code commands.

❓ Architecture

advanced

Which architecture best secures user passwords in Firebase Authentication?

How does Firebase Authentication handle user passwords to keep them secure?

A Passwords are hashed and salted securely by Firebase Authentication service.

B Passwords are stored in plain text in Firebase database for quick access.

C Passwords are encrypted on the client and sent as encrypted blobs to Firebase.

D Passwords are stored in user metadata fields accessible by developers.

💡 Hint

Consider industry best practices for password storage.

Firebase Authentication securely hashes and salts passwords internally, so developers never see raw passwords.

✅ Best Practice

expert

What is the recommended way to handle failed login attempts to prevent brute force attacks?

In Firebase Email/Password login, what is the best practice to protect against repeated failed login attempts?

A Use Firebase's built-in rate limiting and monitor suspicious activity via Firebase Console.

B Implement Firebase Authentication triggers to lock accounts after multiple failed attempts.

C Require users to change their password after every failed login attempt.

D Disable email/password login and only allow anonymous sign-in.

💡 Hint

Think about Firebase's native protections and monitoring tools.

Firebase Authentication includes built-in protections like rate limiting and provides monitoring tools to detect suspicious login attempts.