Plug-and-Patch: Secure Value Added Services for Electric Vehicle Charging

The public charging infrastructure is one of the key factors defining the adoption of Electric Vehicles (EVs), especially for drivers of conventional cars. Yet, building up a large-scale charging network is expensive, and, due to current low demand, its operation does not generate profitability for the providers. Business models involving additional services offered at Charge Points (CPs), so-called Value Added Services (VASs), may strengthen incentives to invest into public charging and its security. In this paper, we analyze main international charging protocols from the functional and security perspective and introduce the first, to the best of our knowledge, full-fledged definition of integrated VASs for Plug-and-Charge (PnC). As an example of such service, we consider securely updating an EV during charging. We propose the Plug-and-Patch (PnP) protocol that allows equipment manufacturers to securely deliver updates for EVs and reliably prove the new firmware state by using a Trusted Platform Module (TPM) 2.0. Also, we specify a message set for VAS required to integrate the PnP service into the PnC protocols ISO 15118 and OCPP 2.0. Our proof-of-concept evaluation shows that the update service adds minimum overhead to the charging process. In order to enable VASs introduced in this work, changes to servers and clients are currently necessary. But considering that the charging standards are continuously reviewed, the respective specifications can be expected to be available by default in the future editions.