Comments on “An Efficient Homomorphic MAC with Small Key Size for Authentication in Network Coding”

Recently, an efficient homomorphic MAC scheme for authentication in network coding is proposed and it is claimed that it achieves a security parameter 1=q^l where l is selected according to different security requirements. However, in this paper, we show that there is an attack to make the security parameter 1=q instead of 1=q^l. And we propose a way to avoid the presented attack.