Analysis of privacy and non-repudiation on pay-TV systems

Lee-Chang-Lin-Hwang (see IEEE Trans. On Consumer Electronics, vol.46, no.1, p.20-26, 2000) in 2000 proposed a set of protocols for pay-TV systems in order to secure subscriber's privacy and build a fair pay-TV system. However, we have found that an attacker can easily get other subscriber's privacy in watching TV-programs. We analyze the reason and discuss the possible amendments. Moreover, we expose a weakness on non-repudiation and suggest an improvement to support non-repudiation.