Vulnerability of an Improved Elliptic Curve Diffie-Hellman Key Agreement and its Enhancement

Authenticated key agreement protocols are a foundation for delivering an authenticated session key between the intended two-party participants from a set of parties over an insecure network. Wang et al proposed protocol ECKE-1N to overcome KCI-R attacks in ECKE-1 as an implicit authenticated key agreement protocol based on Diffie-Hellman elliptic curve. In this paper, we show that ECKE-1N is vulnerable to both leakage of ephemeral private keys and KCI-R attacks. We present an enhanced protocol EECKE-1N, which can withstand KCI-R attacks and revelations both of ephemeral keys. Furthermore, EECKE-1N can provide desirable security proprieties.