Abstract
To ensure that messages can be securely transmitted between different entities in a smart grid, many researchers have focused on authentication and key exchange schemes. Chen et al. recently proposed an authenticated key exchange scheme called PAuth to overcome the defects of the schemes proposed by Mahmood et al. and Abbasinezhad-Mood et al. However, we found that the PAuth scheme proposed by Chen et al. still suffers from some security defects. In this study, we show the detailed attack steps. Then, an enhanced scheme based on PAuth is proposed. Formal and informal security analyses are provided to demonstrate the improved security of the proposed scheme. ProVerif, an automatic cryptographic protocol verifier, is also used to analyze the enhanced scheme. We present the detailed implementation code used in ProVerif. A comparison of the computational and communication costs with those of some previous schemes is provided in the last section of the paper.