V2G的概念主要是利用電動車與智慧電網通訊，以傳輸智慧電網所需電力至電網中。透過電動車於尖峰時間放電與離峰時間充電之機制，V2G網路為智慧電網帶來相當大之助益。由於網路之規模、車速、車輛地理位置，以及車輛互連關係，V2G通訊必須滿足會談金鑰快速建立之需求。再者，電動車之電量資訊密集地傳送亦可能導致電動車車主隱私揭露之問題，而目前相關文獻甚少探討具隱私保護之V2G通訊協定。有鑑於此，我們提出一套具隱私保護之V2G門檻式會談金鑰建立機制，其採用對稱式加密與門檻式秘密分享技術以保護電動車車主之身份，同時建立集電器與電動車之共同會談金鑰。本論文所提機制可滿足身份隱私、通訊機密，以及已知金鑰安全等特性，同時有效抵禦重送攻擊、偽造攻擊，以及中間者攻擊。

The concept of vehicle-to-grid (V2G) is that electric vehicles (EVs) communicate with the smart grid to sell demand response services by delivering electricity into the grid. By letting EVs discharge during peak hours and charge during off-peak hours, V2G networks could bring numerous social and technical benefits to the smart grid. Due to the scale of the network, the speed of the vehicles, their geographic positions, and the very sporadic connectivity between them, V2G communications have the crucial requirements of fast session key establishment. In addition, the close charging message transmission might raise privacy concerns from the EV owners about identity and location information leakage. To the best of the author's knowledge, V2G communication protocol with privacy-preserving has been proposed rarely in the literature. Therefore, we propose a threshold-based session key generation scheme with privacy preservation for V2G networks, which utilizes the symmetric encryption and threshold secret sharing technique to protect the identities of the EV owners and to establish the shared session key between the aggregator and the vehicle. The proposed scheme can achieve the property of identity privacy, confidentiality of the communications, and known-key security, and is secure against the replay attacks, forgery attacks, and man-in-the-middle-attacks.