Efficient authenticated encryption schemes with public verifiability

An authenticated encryption scheme allows messages to be encrypted and authenticated simultaneously. C. Ma and K. Chen proposed such a scheme with public verifiability (see Electronics Letters, vol.39, no.3 p.281-2, 2003). That is, in their scheme, the receiver can efficiently prove to a third party that a message has indeed originated from a specific sender. We first identify two security weaknesses in the Ma-Chen authenticated encryption scheme. Then, based on the Schnorr signature, we proposed an efficient and secure improved scheme such that all the desired security requirements are satisfied.