SecureStore for sensitive data in React Native - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ ui_behavior

intermediate

What happens when you try to retrieve a non-existent key from SecureStore?

Consider this React Native code snippet using SecureStore to get a value for a key that was never saved. What will be the output?

React Native

import * as SecureStore from 'expo-secure-store';

async function getValue() {
  const result = await SecureStore.getItemAsync('missingKey');
  console.log(result);
}

getValue();

A Empty string ('')

B undefined

C Throws an error

D null

💡 Hint

Think about what SecureStore returns when the key does not exist.

SecureStore.getItemAsync returns null if the key is not found. It does not throw an error or return undefined or empty string.

❓ lifecycle

intermediate

When should you clear sensitive data from SecureStore in a React Native app?

You store a user's authentication token in SecureStore. When is the best time to remove this token to keep the app secure?

A When the app goes to background

B When the app is closed by the user

C When the user logs out

D Never remove it to keep user logged in

💡 Hint

Think about user control and security best practices.

Sensitive data like auth tokens should be removed when the user logs out to prevent unauthorized access. Closing or backgrounding the app does not guarantee security.

📝 Syntax

advanced

Which code snippet correctly saves and retrieves a password securely using SecureStore?

Choose the option that correctly saves a password and then retrieves it asynchronously using SecureStore in React Native.

A

await SecureStore.setItemAsync('password', 'myPass123');
const pass = await SecureStore.getItemAsync('password');
console.log(pass);

B

SecureStore.setItem('password', 'myPass123');
const pass = SecureStore.getItem('password');
console.log(pass);

C

await SecureStore.save('password', 'myPass123');
const pass = await SecureStore.load('password');
console.log(pass);

D

SecureStore.setItemAsync('password', 'myPass123');
const pass = SecureStore.getItemAsync('password');
console.log(pass);

💡 Hint

Remember the exact method names and that these are async functions.

The correct methods are setItemAsync and getItemAsync, both returning promises that must be awaited. Option A uses these correctly. Option A uses wrong method names and no await. Option A uses non-existent methods. Option A misses await on calls.

🔧 Debug

advanced

Why does this SecureStore code fail to save data?

Identify the reason this code does not save the data as expected.

React Native

import * as SecureStore from 'expo-secure-store';

function saveData() {
  SecureStore.setItemAsync('token', 'abc123');
}
saveData();

A Wrong method name, should be saveItemAsync

B Missing await before SecureStore.setItemAsync call

C SecureStore requires a callback, not a promise

D Key 'token' is reserved and cannot be used

💡 Hint

Check how async functions should be handled.

SecureStore.setItemAsync returns a promise. Without await or then, the function may not complete before the app continues, causing unexpected behavior. The method name is correct, no callbacks needed, and keys are not reserved.

🧠 Conceptual

expert

What is the main security advantage of using SecureStore over AsyncStorage for sensitive data?

Choose the best explanation for why SecureStore is preferred for storing sensitive information like passwords or tokens.

A SecureStore encrypts data and stores it in the device's secure hardware-backed storage, while AsyncStorage stores data unencrypted in plain text.

B SecureStore automatically backs up data to the cloud, AsyncStorage does not.

C SecureStore is faster than AsyncStorage for large data sets.

D SecureStore allows data sharing between apps, AsyncStorage does not.

💡 Hint

Think about data protection and encryption.

SecureStore uses the device's secure enclave or keystore to encrypt and protect data, making it much safer for sensitive info. AsyncStorage stores data as plain text files, which can be accessed if the device is compromised.

Practice

1. What is the main purpose of using SecureStore in a React Native app?

easy

A. To speed up app animations

B. To store large files like images and videos

C. To manage app navigation between screens

D. To safely save sensitive data like passwords and tokens on the device

Solution

1. Step 1: Understand SecureStore's role

   SecureStore is designed to securely save sensitive data on mobile devices.

2. Step 2: Identify correct use case

   It is perfect for storing passwords, tokens, and private keys, not for files or UI tasks.

3. Final Answer:

   To safely save sensitive data like passwords and tokens on the device -> Option D

4. Quick Check:

   SecureStore purpose = safe sensitive data storage [OK]

Hint: SecureStore is for sensitive data, not files or UI [OK]

Common Mistakes:

• Confusing SecureStore with file storage
• Thinking SecureStore manages UI or navigation
• Using SecureStore for non-sensitive data

2. Which of the following is the correct syntax to save a value using SecureStore in React Native?

easy

A. SecureStore.storeItem('key', 'value');

B. SecureStore.save('key', 'value');

C. await SecureStore.setItemAsync('key', 'value');

D. await SecureStore.putItem('key', 'value');

Solution

1. Step 1: Recall SecureStore method names

   The correct method to save data is setItemAsync, which returns a promise.

2. Step 2: Check syntax correctness

   await SecureStore.setItemAsync('key', 'value'); uses await SecureStore.setItemAsync('key', 'value'); which is correct syntax.

3. Final Answer:

   await SecureStore.setItemAsync('key', 'value'); -> Option C

4. Quick Check:

   Save data = setItemAsync with await [OK]

Hint: Use setItemAsync with await to save data [OK]

Common Mistakes:

• Using incorrect method names like save or putItem
• Forgetting to use await with async methods
• Calling methods without Async suffix

3. What will be the output of this code snippet?

await SecureStore.setItemAsync('token', 'abc123');
const token = await SecureStore.getItemAsync('token');
console.log(token);

medium

A. 'abc123'

B. undefined

C. null

D. Error: Method not found

Solution

1. Step 1: Save a value with setItemAsync

   The code saves the string 'abc123' under the key 'token'.

2. Step 2: Retrieve the saved value with getItemAsync

   Then it fetches the value for 'token', which returns 'abc123'.

3. Final Answer:

   'abc123' -> Option A

4. Quick Check:

   Save then get returns saved string [OK]

Hint: getItemAsync returns saved value if key exists [OK]

Common Mistakes:

• Expecting undefined or null instead of saved value
• Confusing method names or forgetting await
• Assuming error if key exists

4. Identify the error in this code snippet that tries to delete a stored item:

SecureStore.deleteItem('userPassword');

medium

A. Method name should be deleteItemAsync and must be awaited

B. Key 'userPassword' must be a number, not string

C. deleteItem does not exist; use removeItem instead

D. No error; code is correct

Solution

1. Step 1: Check method name for deleting data

   The correct method is deleteItemAsync, not deleteItem.

2. Step 2: Remember async methods require await

   Since it returns a promise, it should be called with await.

3. Final Answer:

   Method name should be deleteItemAsync and must be awaited -> Option A

4. Quick Check:

   Delete method = deleteItemAsync with await [OK]

Hint: Use deleteItemAsync with await to remove data [OK]

Common Mistakes:

• Using wrong method name deleteItem
• Not awaiting async calls
• Thinking key must be a number

5. You want to securely store a user's session token and then immediately retrieve it to verify. Which code snippet correctly does this with error handling?

hard

A. SecureStore.setItem('session', token);
const saved = SecureStore.getItem('session');
console.log(saved);

B. try {
await SecureStore.setItemAsync('session', token);
const saved = await SecureStore.getItemAsync('session');
console.log(saved);
} catch (e) {
console.error(e);
}

C. await SecureStore.saveItem('session', token);
const saved = await SecureStore.getItemAsync('session');
console.log(saved);

D. try {
SecureStore.setItemAsync('session', token);
const saved = SecureStore.getItemAsync('session');
console.log(saved);
} catch (e) {
console.error(e);
}

Solution

1. Step 1: Use correct async methods with await

   Only try { await SecureStore.setItemAsync('session', token); const saved = await SecureStore.getItemAsync('session'); console.log(saved); } catch (e) { console.error(e); } uses setItemAsync and getItemAsync with await properly.

2. Step 2: Include error handling with try-catch

   try { await SecureStore.setItemAsync('session', token); const saved = await SecureStore.getItemAsync('session'); console.log(saved); } catch (e) { console.error(e); } wraps calls in try-catch to handle possible errors safely.

3. Step 3: Identify incorrect method names and missing awaits

   The other options use wrong method names or miss awaits causing errors or wrong behavior.

4. Final Answer:

   Code with await and try-catch -> Option B

5. Quick Check:

   Correct async calls + error handling = try { await SecureStore.setItemAsync('session', token); const saved = await SecureStore.getItemAsync('session'); console.log(saved); } catch (e) { console.error(e); } [OK]

Hint: Always await async SecureStore calls and use try-catch [OK]

Common Mistakes:

• Not awaiting async methods
• Using wrong method names like setItem or saveItem
• Skipping error handling for async calls