Improvements of authenticated encryption schemes with message linkages for message flows

Recently, Tseng et al. proposed two authenticated encryption schemes (basic scheme and generalized scheme) with message linkages, which are efficient in terms of the communication and computation costs in comparison with all the previously proposed schemes. The basic authenticated encryption scheme suited for only after receiving the entire signature blocks, the recipient can then recover the message blocks. In order to allow the receiver to perform the receiving and the recovering processes simultaneously according to application requirements and the transmission efficiency of the network, the generalized authenticated encryption scheme was then proposed. In this paper, we show that both Tseng et al.’s authenticated encryption schemes do not achieve integrity and authentication. Improvements are then proposed to repair the weaknesses.