Password-based encryption

One of the larger issues with encryption is the management and secure storage of encryption keys. Until now and in the pervious recipes, we have settled for storing the key in SharedPreferences as recommended on the Google developer's blog; however, this is not ideal for rooted devices. On rooted devices, you cannot rely on the Android system security sandbox as the root user has access to all areas. By that we mean, unlike on a unrooted device, other apps can obtain elevated root privileges.

The potential for an insecure app sandbox is an ideal case for password-based encryption (PBE). It offers the ability to create (or more correctly derive) the encryption key at runtime using a passcode/password that is usually supplied by the user.

Another solution for key management is to use a system keychain; Android's version of this is called the Android KeyStore, which we will review in a later recipe.

Getting ready

PBE is part of the Java Cryptography Extension, and so...