SecureStore for sensitive data in React Native

Introduction

SecureStore helps you save secret information safely on a phone. It keeps passwords or tokens hidden from others.

Saving a user's login password securely.

Storing an API token for accessing a web service.

Keeping a secret key for encrypting data.

Remembering user preferences that should stay private.

Syntax

React Native

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

// Save data
await SecureStore.setItemAsync(key, value);

// Get data
const result = await SecureStore.getItemAsync(key);

// Delete data
await SecureStore.deleteItemAsync(key);

Use setItemAsync to save data securely.

Use getItemAsync to read saved data.

Examples

Saves the token 'abc123' under the key 'userToken'.

React Native

await SecureStore.setItemAsync('userToken', 'abc123');

Reads the token saved with key 'userToken'.

React Native

const token = await SecureStore.getItemAsync('userToken');

Deletes the saved token for 'userToken'.

React Native

await SecureStore.deleteItemAsync('userToken');

Sample App

This app has three buttons to save, read, and delete a secret value securely. The secret is shown below when read.

React Native

import React, { useState } from 'react';
import { View, Button, Text, Alert } from 'react-native';
import * as SecureStore from 'expo-secure-store';

export default function App() {
  const [storedValue, setStoredValue] = useState('');

  async function saveValue() {
    await SecureStore.setItemAsync('secret', 'myPassword123');
    Alert.alert('Value saved securely!');
  }

  async function readValue() {
    const result = await SecureStore.getItemAsync('secret');
    setStoredValue(result || 'No value found');
  }

  async function deleteValue() {
    await SecureStore.deleteItemAsync('secret');
    setStoredValue('');
    Alert.alert('Value deleted!');
  }

  return (
    <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>
      <Button title="Save Secret" onPress={saveValue} />
      <Button title="Read Secret" onPress={readValue} />
      <Button title="Delete Secret" onPress={deleteValue} />
      <Text style={{ marginTop: 20 }}>{storedValue}</Text>
    </View>
  );
}

Important Notes

SecureStore works differently on iOS and Android but keeps data safe on both.

Always use async/await because these functions return promises.

Do not store very large data; SecureStore is for small secrets only.

Summary

SecureStore saves sensitive data safely on mobile devices.

Use setItemAsync, getItemAsync, and deleteItemAsync to manage data.

It is perfect for passwords, tokens, and private keys.

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