Techniques and tools are described which provide control access mechanisms for contents made available by a service provider to a user. The user, after a registration process, uses a mobile application on a mobile device to generate a one-time content key. The content key is input into a set-top box which validates the key and provides access to the protected content. The mobile application allows for password protection for the user, as well as a recharging ability when its one-time content keys are exhausted.