Recent advances in hardware, software, computing, and communication technologies have enabled the design and deployment of a smarter, interactive, dynamic 21st cen-tury electrical grid, also known as the smart grid. The bi-directional ow of information between the customer premise and the utility provider opens up several privacy challenges that must beaddressed. We describe possi-ble man-in-the-middle attacks against one (proposed by Marmol et al.) of the recently propsed privacy solu-tions for the smart grid environment. To address this vulnerability, we propose an improved privacy solution. We demonstrate the robustness and efficiency of our so-lution through a detailed security analysis.