Conditional access system interoperability through software downloading

Interoperability between conditional access (CA) systems and set-top boxes (STB)-CA-STB interoperability-has been an issue from the very beginning of receiver development for digital pay-TV. Interoperability ensures that any service can be received on any (interoperable) STB. The common interface solutions SimulCrypt and MultiCrypt are now standardized. However, these solutions have a number of disadvantages, including the need for service providers to agree on using each other´s system, increased bandwidth usage, inflexibility, cost, and limited functionality. This paper describes another solution for CA-STB interoperability, based on downloading interoperable software into the STB. It provides full CA-STB interoperability. Furthermore, it can be introduced relatively easily into future STBs and will require only minimal changes in current CA systems