A Flexible Subscription Model for Broadcasted Digital Contents

This paper introduces subscriptions as authorizations to access contents within time periods. For a technical real- ization of the subscriptions, a new key assignment scheme is proposed that supports fine-granular adjustable restrictions on both, contents and validity duration. Its security is based on the reliance of tamper-proof devices and hash functions. Since per subscription only one key pair is required, it is very suitable in practice. Additionally, a concept based on prepaid cards is given that unburdens the server from user authentication and preserves the users' anonymity.