Secure Communication in Digital TV Broadcasting

To provide subscription-based Digital TV (DTV) data, services providers scramble the data stream (program content) with some secure measures such as ECM and EMM via using control words, and send the stream to conditional access system (CAS) in the set-top box (STB). Smart card is used to decrypt the control words and accordingly to enable the STB to descramble the scrambled signal. Therefore, secure communication between STB and smart card is a key issue to the service providers. The paper discusses and identifies some security issues in previous research works that have focused on secure communication between smart card and STB. Then, it proposes a secure mutual authentication and a key agreement protocol between smart card and STB. The proposed scheme is more efficient and secure than previously proposed schemes in that it eliminates time-consuming exponentiation operation. The proposed scheme also prevents smart card cloning and McCormac Hack problems.