Expo SecureStore iconExpo SecureStore

GitHub

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

Android
iOS
tvOS

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

Terminal
npx expo install expo-secure-store

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

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

Configurable properties

NameDefaultDescription
configureAndroidBackuptrue
Only for:
Android

A boolean indicating whether to configure automatic Android backup to work correctly with expo-secure-store. Learn more.

faceIDPermission"Allow $(PRODUCT_NAME) to access your Face ID biometric data."
Only for:
iOS

A string to set the NSFaceIDUsageDescription permission message.

Are you using this library in a bare React Native app?

Add NSFaceIDUsageDescription key to Info.plist:

Info.plist
<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:

app.json
{
  "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

SecureStore
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

Android
iOS
tvOS

SecureStore.AFTER_FIRST_UNLOCK

Type: KeychainAccessibilityConstant


The data in the keychain item cannot be accessed after a restart until the device has been unlocked once by the user. This may be useful if you need to access the item when the phone is locked.

Android
iOS
tvOS

SecureStore.AFTER_FIRST_UNLOCK_THIS_DEVICE_ONLY

Type: KeychainAccessibilityConstant


Similar to AFTER_FIRST_UNLOCK, except the entry is not migrated to a new device when restoring from a backup.

Deprecated Use an accessibility level that provides some user protection, such as AFTER_FIRST_UNLOCK.

Android
iOS
tvOS

SecureStore.ALWAYS

Type: KeychainAccessibilityConstant


The data in the keychain item can always be accessed regardless of whether the device is locked. This is the least secure option.

Deprecated Use an accessibility level that provides some user protection, such as AFTER_FIRST_UNLOCK_THIS_DEVICE_ONLY.

Android
iOS
tvOS

SecureStore.ALWAYS_THIS_DEVICE_ONLY

Type: KeychainAccessibilityConstant


Similar to ALWAYS, except the entry is not migrated to a new device when restoring from a backup.

Android
iOS
tvOS

SecureStore.WHEN_PASSCODE_SET_THIS_DEVICE_ONLY

Type: KeychainAccessibilityConstant


Similar to WHEN_UNLOCKED_THIS_DEVICE_ONLY, except the user must have set a passcode in order to store an entry. If the user removes their passcode, the entry will be deleted.

Android
iOS
tvOS

SecureStore.WHEN_UNLOCKED

Type: KeychainAccessibilityConstant


The data in the keychain item can be accessed only while the device is unlocked by the user.

Android
iOS
tvOS

SecureStore.WHEN_UNLOCKED_THIS_DEVICE_ONLY

Type: KeychainAccessibilityConstant


Similar to WHEN_UNLOCKED, except the entry is not migrated to a new device when restoring from a backup.

Methods

Android
iOS

SecureStore.canUseBiometricAuthentication()

Checks if the value can be saved with requireAuthentication option enabled.

Returns:

boolean

true if the device supports biometric authentication and the enrolled method is sufficiently secure. Otherwise, returns false. Always returns false on tvOS.

Android
iOS
tvOS

SecureStore.deleteItemAsync(key, options)

ParameterTypeDescription
keystring

The key that was used to store the associated value.

options
(optional)
SecureStoreOptions

An SecureStoreOptions object.

Default:{}

Delete the value associated with the provided key.

Returns:

Promise<void>

A promise that rejects if the value can't be deleted.

Android
iOS
tvOS

SecureStore.getItem(key, options)

ParameterTypeDescription
keystring

The key that was used to store the associated value.

options
(optional)
SecureStoreOptions

An SecureStoreOptions object.

Default:{}

Synchronously reads the stored value associated with the provided key.

Note: This function blocks the JavaScript thread, so the application may not be interactive when reading a value with requireAuthentication option set to true until the user authenticates.

Returns:

string | null

Previously stored value. It resolves with null if there is no entry for the given key or if the key has been invalidated.

Android
iOS
tvOS

SecureStore.getItemAsync(key, options)

ParameterTypeDescription
keystring

The key that was used to store the associated value.

options
(optional)
SecureStoreOptions

An SecureStoreOptions object.

Default:{}

Reads the stored value associated with the provided key.

Returns:

Promise<string | null>

A promise that resolves to the previously stored value. It resolves with null if there is no entry for the given key or if the key has been invalidated. It rejects if an error occurs while retrieving the value.

Keys are invalidated by the system when biometrics change, such as adding a new fingerprint or changing the face profile used for face recognition. After a key has been invalidated, it becomes impossible to read its value. This only applies to values stored with requireAuthentication set to true.

Android
iOS
tvOS

SecureStore.isAvailableAsync()

Returns whether the SecureStore API is enabled on the current device. This does not check the app permissions.

Returns:

Promise<boolean>

Promise which fulfils witch boolean, indicating whether the SecureStore API is available on the current device. Currently, this resolves true on Android and iOS only.

Android
iOS
tvOS

SecureStore.setItem(key, value, options)

ParameterTypeDescription
keystring

The key to associate with the stored value. Keys may contain alphanumeric characters, ., -, and _.

valuestring

The value to store. Size limit is 2048 bytes.

options
(optional)
SecureStoreOptions

An SecureStoreOptions object.

Default:{}

Stores a key–value pair synchronously.

Note: This function blocks the JavaScript thread, so the application may not be interactive when the requireAuthentication option is set to true until the user authenticates.

Returns:

void

Android
iOS
tvOS

SecureStore.setItemAsync(key, value, options)

ParameterTypeDescription
keystring

The key to associate with the stored value. Keys may contain alphanumeric characters, ., -, and _.

valuestring

The value to store. Size limit is 2048 bytes.

options
(optional)
SecureStoreOptions

An SecureStoreOptions object.

Default:{}

Stores a key–value pair.

Returns:

Promise<void>

A promise that rejects if value cannot be stored on the device.

Types

Android
iOS
tvOS

KeychainAccessibilityConstant

Type: number

Android
iOS
tvOS

SecureStoreOptions

NameTypeDescription
authenticationPrompt
(optional)
string

Custom message displayed to the user while requireAuthentication option is turned on.

keychainAccessible
(optional)
KeychainAccessibilityConstant
Only for:
iOS

Specifies when the stored entry is accessible, using iOS's kSecAttrAccessible property.

Default:SecureStore.WHEN_UNLOCKED

See: Apple's documentation on keychain item accessibility.

keychainService
(optional)
string
  • Android: Equivalent of the public/private key pair Alias.
  • iOS: The item's service, equivalent to kSecAttrService.

If the item is set with the keychainService option, it will be required to later fetch the value.

requireAuthentication
(optional)
boolean

Option responsible for enabling the usage of the user authentication methods available on the device while accessing data stored in SecureStore.

  • Android: Equivalent to setUserAuthenticationRequired(true) (requires API 23).
  • iOS: Equivalent to biometryCurrentSet. Complete functionality is unlocked only with a freshly generated key - this would not work in tandem with the keychainService value used for the others non-authenticated operations.

This option works slightly differently across platforms: On Android, user authentication is required for all operations. On iOS, the user is prompted to authenticate only when reading or updating an existing value (not when creating a new one).

Warning: This option is not supported in Expo Go when biometric authentication is available due to a missing NSFaceIDUsageDescription. In release builds or when using continuous native generation, make sure to use the expo-secure-store config plugin.