On the Design of High-Speed Pseudorandom bit Generators for Secure Broadcasting Systems

Pseudorandom bit generators play an essential role in audio or video conditional-access control systems which allow broadcasting programs to be viewed only by authorized subscribers. This paper evaluated cryptographic strength of bit generators proposed by the European Broadcast Unit (EBU) and the Japan's Ministry of Posts and Telecommunications and some security weakness was found on the generators. Subsequently we gave a method to safeguard the EBU's sequence generators that is free from any known cryptologic weakness and we also proposed a self clock-control scheme which generates sequences with non-Mersenne prime periods suitable for cryptographic purposes.