flutter_secure_storage on mobile should be your first and only choice. It uses the proper Keychain API on iOS and it encrypts the data , stores the encrypted data in SharedPreferences and the cryptographic key is stored in the Android KeyStore, which is a safe approach.29 Nis 2020
Read moreIs flutter secure storage persistent?
Yes it saves once the app is closed . You can check the example app here: github.com/mogol/flutter_secure_storage/tree/develop/example This shows that keys can be created and once the app is closed and reopened, the keys are not wiped.
Read moreHow do you store secure data in flutter?
A Flutter plugin to store data in secure storage:
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