Usually pay TV decoder devices (also called Set-Top Box-STB) perform content reception, descrambling, and decoding processes and eventually presenting content to ren dering devices such as TV sets.As the pay TV content is not for free, the protection of pay TV content at STB is very important.Nowadays pay TV operators suffer from various piracy problems due to poor security of STB chips.Therefore security design and evaluation be come important and mandatory for decoder chip certification.In this talk, I will introduce the advanced security features on the latest decoder chips and the potential threats and at tacks and the methodology to evaluate the decoder chips.