Expo SecureStore

A library that provides a way to encrypt and securely store key-value pairs locally on the device.

expo-secure-store provides a way to encrypt and securely store key-value pairs locally on the device. Each Expo project has a separate storage system and has no access to the storage of other Expo projects.

Size limit for a value is 2048 bytes. An attempt to store larger values may fail. Currently, we print a warning when the limit is reached, however, in a future SDK version an error might be thrown.

The requireAuthentication option is not supported in Expo Go when biometric authentication is available due to a missing NSFaceIDUsageDescription key.

This API is not compatible with devices running Android 5 or lower.

Installation

If you are installing this in an existing React Native app, start by installing expo in your project. Then, follow the additional instructions as mentioned by the library's README under "Installation in bare React Native projects" section.

Configuration in app.json/app.config.js

You can configure expo-secure-store using its built-in config plugin if you use config plugins in your project (EAS Build or npx expo run:[android|ios]). The plugin allows you to configure various properties that cannot be set at runtime and require building a new app binary to take effect.

Example app.json with config plugin

{
  "expo": {
    "plugins": [
      [
        "expo-secure-store",
        {
          "configureAndroidBackup": true,
          "faceIDPermission": "Allow $(PRODUCT_NAME) to access your Face ID biometric data."
        }
      ]
    ]
  }
}

Configurable properties

<key>NSCameraUsageDescription</key>
<string>Allow $(PRODUCT_NAME) to use the camera</string>

Platform value storage

Android

On Android, values are stored in SharedPreferences, encrypted with Android's Keystore system.

iOS

For iOS standalone apps, data stored with expo-secure-store can persist across app installs.

On iOS, values are stored using the keychain services as kSecClassGenericPassword. iOS has the additional option of being able to set the value's kSecAttrAccessible attribute, which controls when the value is available to be fetched.

Data persistence

expo-secure-store is designed to provide a persistent data storage solution across app restarts and updates. However, it is important not to rely on it as a single source of truth for irreplaceable, critical data. Data saved using expo-secure-store will not be preserved upon app uninstallation. Additionally, any data protected with the requireAuthentication option set to true will become inaccessible if there are changes to the user's biometric settings, such as adding a new fingerprint.

Exempting encryption prompt

Apple App Store Connect prompts you to select the type of encryption algorithm your app implements. This is known as Export Compliance Information. It is asked when publishing the app or submitting for TestFlight.

When using expo-secure-store, you can set the ios.config.usesNonExemptEncryption property to false in the app config:

{
  "expo": {
    "ios": {
      "config": {
        "usesNonExemptEncryption": false
      }
      %%placeholder-start%%... %%placeholder-end%%
    }
  }
}

Setting this property automatically handles the compliance information prompt.

Android Auto Backup

Android Auto Backup for Apps automatically backs up a user's data from apps that target and run on Android 6.0 (API level 23) or higher.

The Auto Backup system has to be configured to exclude expo-secure-store shared preferences entries, as it's impossible to decrypt them after restoring the backup — app's entries are deleted from the Android Key Store when the app is uninstalled.

If your app doesn't have any custom backup configuration, expo-secure-store will automatically configure the Auto Backup system to ignore the expo-secure-store data.

If you are using your own Auto Backup configuration, you should exclude the SecureStore under the sharedpref domain and set the configureAndroidBackup to false in the config plugin configuration.

<!--  Auto Backup configuration for Android 12 and higher -->
<data-extraction-rules>
  <cloud-backup>
    <include domain="sharedpref" path="."/>
    <exclude domain="sharedpref" path="SecureStore"/>
  </cloud-backup>
  <device-transfer>
    <include domain="sharedpref" path="."/>
    <exclude domain="sharedpref" path="SecureStore"/>
  </device-transfer>
</data-extraction-rules>

<!--  Auto Backup configuration for Android 11 and lower -->
<full-backup-content>
  <include domain="sharedpref" path="."/>
  <exclude domain="sharedpref" path="SecureStore"/>
</full-backup-content>

Usage

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

async function save(key, value) {
  await SecureStore.setItemAsync(key, value);
}

async function getValueFor(key) {
  let result = await SecureStore.getItemAsync(key);
  if (result) {
    alert("🔐 Here's your value 🔐 \n" + result);
  } else {
    alert('No values stored under that key.');
  }
}

export default function App() {
  const [key, onChangeKey] = useState('Your key here');
  const [value, onChangeValue] = useState('Your value here');

  return (
    <View style={styles.container}>
      <Text style={styles.paragraph}>Save an item, and grab it later!</Text>
      {%%placeholder-start%%Add some TextInput components... %%placeholder-end%%}

      <TextInput
        style={styles.textInput}
        clearTextOnFocus
        onChangeText={text => onChangeKey(text)}
        value={key}
      />
      <TextInput
        style={styles.textInput}
        clearTextOnFocus
        onChangeText={text => onChangeValue(text)}
        value={value}
      />
      {}
      <Button
        title="Save this key/value pair"
        onPress={() => {
          save(key, value);
          onChangeKey('Your key here');
          onChangeValue('Your value here');
        }}
      />
      <Text style={styles.paragraph}>🔐 Enter your key 🔐</Text>
      <TextInput
        style={styles.textInput}
        onSubmitEditing={event => {
          getValueFor(event.nativeEvent.text);
        }}
        placeholder="Enter the key for the value you want to get"
      />
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    paddingTop: 10,
    backgroundColor: '#ecf0f1',
    padding: 8,
  },
  paragraph: {
    marginTop: 34,
    margin: 24,
    fontSize: 18,
    fontWeight: 'bold',
    textAlign: 'center',
  },
  textInput: {
    height: 35,
    borderColor: 'gray',
    borderWidth: 0.5,
    padding: 4,
  },
});

API

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

Constants

Methods

Types