Design and Evaluation of a New Scheme Based on Secret Sharing Mechanisms that Increases the Security of Conditional Access Systems in Satellite Pay-TV

作者：Spaliaras Iraklis^*; Dokouzyannis Stavros

来源：Wireless Personal Communications, 2015, 82(3): 1461-1481.

DOI：10.1007/s11277-015-2293-6

• Conditional access system
• Key distribution
• Pay-TV
• Newton interpolation
• Security
• Smart card

This paper introduces a new scheme that confronts one of the critical flaws of conditional access (CA) systems employed in satellite pay-TV, the long or infinite cryptoperiod of a master key (MK). Through the new scheme, which is based on Shamir's secret sharing and Simmons' prepositioned shared secret scheme, the administrator of the CA system is able to refresh the MKs of all the users by simply broadcasting a common message of 256 bits. As a result, the vulnerabilities introduced by the long or infinite cryptoperiod of MKs are alleviated. Newton interpolation (NI) is utilized to accomplish the refreshment of the MK, and its scalability is fully exploited. Therefore, as it is verified by the implementation of NI on ATmega128, the MK can be refreshed in < 0.05 s, depending on the desired security level. Moreover, the increase in the security that the new scheme provides is analyzed. A security comparison with the CA systems presented in the literature proves the superiority of the proposed scheme. Finally, the bandwidth overhead of the new scheme is estimated by comparing it to the bandwidth that is assigned to several modern CA systems of the pay-TV market, and it is proven to be negligible.

• 出版日期2015-6