A Research on Access Protection for Mobile Pay-TV Systems

Abstract

In recent years, with the digital convergence of broadcast and wireless communication, mobile pay-TV services are getting more and more attention. However, a mobile pay-TV system is very vulnerable to malicious attacks. To provide a secure mobile pay-TV service, a secure access protection for pay-TV systems plays an important role. Therefore, to guarantee a secure access of services by authorized users, the access protection is required. In a mobile pay-TV system, under a proper access protection, only the authorized users can access and decrypt their authorized contents. With the gradual integration of heterogeneous networks, to provide secure video services in a public network, video encryption is required. To provide such an access protection, access control and video encryption are important issues. However, since the bandwidth of a broadcast channel and the resources in a mobile set are limited, both a better broadcast efficiency and low computation cost of an access protection are required. In this dissertation, an access protection for mobile pay-TV systems is explored; in that an efficient authentication for access control and an efficient selective video encryption scheme are addressed and discussed. In the access control, we propose an efficient authentication schemes for mobile pay-TV systems. In a mobile pay-TV system, a large number of messages are exchanged for mutual authentication. An efficient and secure authentication mechanism for access control is required. In traditional authentication schemes, with one-to-one delivery, one authentication message per request is delivered from a head end system to subscribers. This results in the delivery of a large quantity of messages and therefore is inefficient and costly. Due to its wireless nature, mobile pay-TV is vulnerable to attacks during hand-off. To provide a secure mobile pay-TV service, a hand-off authentication also becomes an important issue. Traditional schemes do not support hand-off authentication and therefore are insecure during hand-off. In this dissertation, we propose an innovative authentication scheme employing Elliptic Curve Cryptography, in which, by providing one-to-many facility, only one authentication message for multiple requests is broadcasted from the head end system to subscribers. This new scheme achieves better broadcast efficiency and performance on communication costs than traditional schemes. Additionally, our scheme provides a hand-off authentication mechanism to protect the access of services while preventing attacks during hand-off; therefore, the scheme is more secure to support access control. Moreover, the scheme adopts an identity-based scheme to provide anonymous authentication for protecting privacy; hence the scheme inherits advantages of the identity-based scheme. With these advantages of our scheme, it is well suitable for mobile pay-TV system. To provide a better access protection, video encryption is also an important issue. In order to provide video services, service providers and users usually interact through public communication channels. However, these public communication channels are vulnerable to attacks, and as a result, video encryption becomes an important issue. Traditional video encryptions are either inefficient or insecure. This dissertation proposes a real-time selective video encryption using context-key control. The new context-key control encryption in this scheme is modified from ElGamal encryption. Using context-key control, our scheme can perform a low exponent operation and secure encryption. We apply our encryption scheme to perform selective encryption on video DCT coefficients. In our performance and security analysis, our scheme is secure and efficient, and can be well applied to the video encryption.