A smart grid (SG), also referred to as an electric grid, represents an exceptionally reliable, efficient, and secure system for transmitting both electricity and data. Researchers and the power industry are becoming increasingly interested in SG because of its varied responsibilities. To achieve secure communication in SG environment, there is a need to establish a key exchange between participants. In an SG environment, a number of key exchange techniques have been developed for secure communication. Nevertheless, the most of them do not offer anonymity and function inadequately for SG communication. In this paper, we propose a robus key exchanged and authentication protocol for SG environment using elliptic curve cryptography. The proposed protocol provides anonymity and mutual authentication between participants in SG environment. In addition to an informal security analysis, we offer a formal security analysis of the proposed protocol based on the random oracle model. Further, we provide comparison of the security and functionality features of the proposed protocol with existing ECC-based protocols. A performance analysis in terms of computational and communication costs is carried out in comparison with existing dozen advanced authentication and key exchanged protocols, showing the superiority of the proposed protocol. Our protocol achieves high security with minimum computational and communication costs. The proposed protocol reduced computational cost $\approx 79.64\%$ , cost of communication is reduced $\approx 71.54 \%$ , while energy consumption reduced to $\approx 79.65 \%$ respectively of the mean value of all alternatives, thus proving the robustness of the presented protocol for securing SG communications.