@op-engineering/op-s2

yarn add @op-engineering/op-s2

---

Modern encryption module for React Native. Uses Keychain on iOS and the official libraries, KeyStore/EncryptedSharedPreferences, on Android.

Created by ospfranco.

Motivation

Other React Native stores hand-roll their encryption, via OpenSSL (does not use hardware when possible) or raw implementation of algorithms (outdated algorithms or improper implementations).

The benefit of using the official implementations is the use of encryption hardware on-device when possible. Using the hardware chips provides yet another layer of security to prevent tampering with the data as it is being decrypted/encrypted/stored.

Examples

import { get, set, ACCESSIBILITY } from '@op-engineering/op-s2';

const { error } = set({
  key: 'myKey',
  value: 'myValue',
  // Only valid for iOS you have more control when to prompt for authentication
  accessibility: ACCESSIBILITY.WHEN_PASSCODE_SET_THIS_DEVICE_ONLY,
  // OR works for both iOS and Android
  withBiometrics: true,
});

const { error, value } = get({
  key: 'myValue',
  withBiometrics: true,
});

const { error } = del({
  key: 'myValue',
  withBiometrics: true,
});

iOS Accessibility

On iOS you can specify an accessibility value which allows you to customize when the data is readable. It is mutually exclusive with withBiometrics. So pick one or the other.

Key	Explanation
AFTER_FIRST_UNLOCK	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.
AFTER_FIRST_UNLOCK_THIS_DEVICE_ONLY	Similar to AFTER_FIRST_UNLOCK, except the entry is not migrated to a new device when restoring from a backup.
ALWAYS	The data in the keychain item can always be accessed regardless of whether the device is locked. This is the least secure option.
ALWAYS_THIS_DEVICE_ONLY	Similar to ALWAYS, except the entry is not migrated to a new device when restoring from a backup.
WHEN_PASSCODE_SET_THIS_DEVICE_ONLY	Similar to WHEN_UNLOCKED_THIS_DEVICE_ONLY, except the user must have set a passcode to store an entry. If the user removes their passcode, the entry will be deleted.
WHEN_UNLOCKED	The data in the keychain item can be accessed only while the device is unlocked by the user.
WHEN_UNLOCKED_THIS_DEVICE_ONLY	Similar to WHEN_UNLOCKED, except the entry is not migrated to a new device when restoring from a backup.

Secure Enclave

The library already uses the Secure Enclave to encrypt the data before saving it on the keychain. However, it is not possible to store data directly on the Secure Enclave as it is meant to store the private part of asymmetrical keys, meaning data saved there cannot be retrieved to user space.

Android Quirks

The official Android crypto implementation uses hardware-backed-up encryption when possible. However, it will depend on the vendor to use the hardware chips or not, there is not much that can be done about that.

The library currently depends on the latest available versions:

androidx.security:security-crypto:1.1.0-alpha06
androidx.biometric:biometric:1.2.0-alpha05

And will be continually updated to support fixes and updates.

TODO

• Add getAllKeys, getAllItems and deleteAllItems methods (if possible)
• Device testing list
• Security audits

License

MIT License