Comments on Harn-Lin's cheating detection scheme

Detection of cheating and identification of cheaters in threshold schemes has been well studied, and several solid solutions have been provided in the literature. This paper analyses Harn and Lin's recent work on cheating detection and identification of cheaters in Shamir's threshold scheme. We will show that, in a broad area, Harn-Lin's scheme fails to detect cheating and even if the cheating is detected cannot identify the cheaters. In particular, in a typical Shamir (t, n)-threshold scheme, where n = 2t - 1 and up to t - 1 of participants are corrupted, their scheme neither can detect nor can identify the cheaters. Moreover, for moderate size of groups their proposed cheaters identification scheme is not practical.