Penetration of Plug in electric vehicles (PEVs) is expected to rise in the next few years especially in areas with new deployed smart power grid systems. Charging and discharging of PEVs will introduce several challenges related to load stabilization and information security. In this paper, we discuss a secure discharging protocol where users can be protected from possible information security and privacy attacks. The protocol also incorporates required remote authorization and payment transaction mechanisms. Our protocol is developed based on the use of encryption mechanisms and the dual signature approach. Using the security protocol verification tool, Automatic Verification and Analysis of Internet Security Protocols (AVISPA), the security aspects of the proposed protocol are verified. Our approach is robust against misuse of electric vehicles and unfair payment issues as it allows for user-based authentication in addition to the authentication of associated electric vehicles.