Certificateless-based two-party authenticated key agreement protocols in a multiple PKG environment

To date, most identity-based key agreement protocols are based on a single PKG (Private Key Generator) environment. However, it is not realistic to assume that all schemes use a single PKG and each PKG shares identical system parameters but possesses a distinct master key. Recently, Lee et al. proposed an ID-based 2-party key agreement protocol between users whose private keys were issued by independent PKGs that do not share any system parameters. However, Lee et al. protocol has a flaw that allows attackers to impersonate others without knowing their private keys and the key escrow issues inherited in the identity-based schemes. In this paper, we propose a new certificateless-based two party authenticated key agreement protocol based on bilinear pairings in elliptic curves between users belonging to different PKGs that do not share identical system parameters. Compared with other two-party key agreement protocols for a multiple PKG environment, the proposed key agreement protocols satisfy every security requirements of key agreement protocols.