Weakness and solution of deniable authentication protocol based on Diffie-Hellman algorithm

Recently, an efficient and non-interactive deniable authentication protocol based on the Diffie-Hellman key distribution protocol is presented by Fen et al. to enable a receiver to identify the source of a given message, but not prove the identity of the sender to a third party. In this paper, we point out that it suffers from an authentication flaw similar to that developed by Lowe to Intruder masquerades as other principals and inquisitor INQ can identify the source of the message unlike their claims. Accordingly, we propose an improved protocol to overcome the weaknesses.