ECC-based key exchange protocol for IPTV service

In IPTV (Internet Protocol Television) broadcasting service environments, service providers charge subscription fee by scrambling the program in CAS (Conditional Access System). These techniques avoid unauthorized users to receive or watch the programs. A smart card is widely used to encrypt or decrypt the Control Words (CW) and transfer them back to the STB (Set-Top Box) in order to descramble the scrambled program. Therefore, secure communication between STB and smart card is directly related to the benefit of the service providers and the legal rights of users, while key exchange is the essential part of a secure communication. This paper presents a new secure and efficient key exchange protocol for IPTV service based on a one-way hash function and Elliptic Curve Diffie-Hellman key exchange algorithm to minimize the complexity of computational costs between the smart card and the STB and fit low-power IPTV broadcasting service environments. Compared with previous schemes, the newly proposed protocol has the following more practical merits: (1) it provides secure session key agreement function by adopting elliptic curve cryptosystem, (2) it can reduce the total execution time and memory requirement due to the elliptic curve cryptography, and (3) it not only is secure against well-known cryptographical attacks but also provides perfect forward secrecy. As a result, the proposed protocol is extremely suitable for use in IPTV broadcasting service environments since it provides security, reliability, and efficiency.