EV Charging Authentication Using PKI and Lightweight CAN Credentials

The patent segments the authentication process into two distinct phases: (1) a setup phase using complex PKI mechanisms to establish long-term digital certificates and keys between the EV and CSMS, and (2) an operational phase using lightweight session tokens and pre-shared keys for actual charging transactions. This segmentation allows the heavy computational burden of PKI to be performed only once during setup, while subsequent communications use simplified authentication methods, thereby resolving the contradiction between security and communication overhead.

The patent implements preliminary action by pre-establishing security credentials and digital certificates between the EV and CSMS before the actual charging transaction occurs. The EV obtains a digital certificate from the CSMS in advance, and both parties pre-share cryptographic keys. When the charging session begins, these pre-established credentials are used to rapidly authenticate the EV without requiring real-time complex PKI operations, thus reducing communication overhead while maintaining high security standards.

The patent introduces an intermediary approach by using the CSMS as a trusted third party that mediates the security relationship between the EV and CS. The CSMS issues digital certificates to the EV and manages the distribution of cryptographic keys. This intermediary enables the EV-CS communication to use lightweight authentication methods (such as token-based authentication) while the CSMS provides the underlying security infrastructure, thus achieving both bandwidth efficiency and security strength simultaneously.

The patent applies parameter changes by dynamically adjusting the authentication mechanism based on the communication medium. For PLC communications, full PKI validation is performed, while for CAN cable communications, the system transitions to using lightweight session tokens derived from pre-shared keys. This parameter change in authentication strength matches the bandwidth characteristics of each communication medium, optimizing both security and bandwidth efficiency for each specific channel.

The patent implements self-service by enabling automatic authentication and billing through the Plug and Charge functionality. The EV automatically presents its digital certificate to the CS upon connection, the CS validates the certificate through secure communication with the EV, and the charging session is automatically authorized and billed without requiring the user to manually insert a payment card or interact with the charging interface. This self-service mechanism ensures reliable revenue collection through automated billing while maximizing user convenience by eliminating all manual payment steps.

The patent replaces the mechanical payment system (physical payment cards, cash handling, manual insertion into card readers) with an electronic cryptographic authentication system. The EV's digital certificate and cryptographic keys substitute for physical payment media, and the secure electronic communication protocol replaces the mechanical card-swiping or cash-handling processes. This substitution eliminates the need for users to carry payment cards or interact with physical payment terminals, thereby improving convenience while maintaining reliable revenue collection through automated electronic billing.