We're still investigating about a big trouble affecting our app on Android 4.2.2 and higher.
A library changing seems to cause issues in encryption randomizer that generates always changing encryption keys. This means that on those Andoird versions it's impossible to decrypt what we just encrypted.
If you plan to upgrade from an older Android version to Android 4.2 or higher please backup all your data using export function before upgrading.
We are actually thinking to release a new version of KeyDroid for Android 4.2 and higher. Back-compatibility seems cannot be guaranteed.
We are very sorry for such a trouble.