Android Securing a Shared Preference


Example

Simple Codec

Here to illustrate the working principle we can use simple encryption and decryption as follows.

public static String encrypt(String input) {
    // Simple encryption, not very strong!
    return Base64.encodeToString(input.getBytes(), Base64.DEFAULT);
}

public static String decrypt(String input) {
    return new String(Base64.decode(input, Base64.DEFAULT));
}

Implementation Technique

public static String pref_name = "My_Shared_Pref";

// To Write
SharedPreferences preferences = getSharedPreferences(pref_name, MODE_PRIVATE);
SharedPreferences.Editor editor = preferences.edit();
editor.putString(encrypt("password"), encrypt("my_dummy_pass"));
editor.apply(); // Or commit if targeting old devices

// To Read
SharedPreferences preferences = getSharedPreferences(pref_name, MODE_PRIVATE);
String passEncrypted = preferences.getString(encrypt("password"), encrypt("default_value"));
String password = decrypt(passEncrypted);