Keywords

MIFARE DUOX, EV charging, electric vehicle charging, EV charging card, NFC, ISO/IEC 14443, ISO/IEC 7816-4, VDE, DKE, VDE-AR-E 2532-100, ECC, ECDSA, asymmetric cryptography, user authentication, user authorization

Abstract

This document describes how MIFARE DUOX can be used for EV charging applications, to authorize and authenticate the end user in a secure and reliable way. The MIFARE DUOX smart card IC can be used as the RFID medium for the EV charging device, in the form of an NFC smart card, NFC keyfob, NFC token, or similar.

Introduction

With the quick expansion of the electromobility market and the growing number of electric vehicles on the road, the demand for robust and reliable electric vehicle charging infrastructure and charging services is rising. In order to charge electric vehicles at charging stations, some means to authorize the charging session and execute the payment is required. Typical mediums in use today are NFC-based smartcards (also often referred to as "RFID cards" within this industry) and mobile devices with dedicated smartphone apps. Using smartcards or mobile devices, users can be uniquely identified, and all user-related data can be easily associated with executed charging sessions, billing data and other statistics. This helps tremendously to enhance transparency and user experience for the end customer. With a simple NFC-based tap onto the NFC reader of an EV charging terminal, the charging session is authorized without the need to enter a password, pin, or credit card details. It offers electric vehicle drivers an easy and convenient way to access public charging private charging stations. EV charging cards can come in any form factor, such as a standard smartcard, tags, tokens, keyfobs, but are all based on the same technology, which is NFC (Near Field Communication), also referred to as RFID (Radio Frequency Identification). EV charging cards can be used with residential chargers to power your vehicle at home, but are more frequently used to gain access to public EV charging, such as stations located on the road, on highways, in cities, at shopping centers, or the workplace. The main benefit of using an EV charging card (NFC-based smart card) is reliability. The EV charging card operates without battery, purely offline, and is resistant to extreme environment conditions such as heat and cold. In contrast to this, an EV charging smartphone app may not be accepted at charging stations, due to technical limitations or non-compliancy. Furthermore, a smartphone app cannot be used if the phone is out of battery.

NFC-based EV charging cards and current market situation

In today’s infrastructure for electric vehicle charging, many charging stations support the use of contactless smartcards, so drivers can stop and start the charging process, make payments, and register data about the charging session with a simple NFC-based tap. Using smartcards at charging stations adds convenience to EV ownership and helps promote wider adoption of EVs. It also makes it easier for charging networks to provide individual drivers and fleet operators with the kinds of data-driven insights that help monitor vehicle safety and manage power consumption for greater sustainability. There are, however, concerns over security. In many cases of EV charging installations that we can find in the field today, the charge point relies on the contactless smart card’s unique identifier (UID) for authentication, which is a practice that is vulnerable to fraud, including the use of cloned or fake smartcards. The UID of a contactless smart card uniquely identifies the card and links it to an EV driver through the EV provider's backend system. The user´s account is linked to the UID when the smart card is issued and is used to look up the user account for every charging session. Since the UID can be easily read out from the charging card and retrieved in plaintext, relying solely on it for authorizing the user poses a high security risk, as hackers can clone the user credential, by simply copying the UID, and charge at another driver's expense. Within this chapter, we want to explore the purpose and benefits of EV charging cards, the different types of cards, as well as the implementation of NFC on currently deployed EV charging stations. The interaction between the NFC reader on the charge point and the EV charging card is essential to ensure security and provide protection of the EV driver´s data.

Benefits and necessity of using NFC-based EV charging cards

EV charging cards are essential for improving the efficiency of the charging operation as well as the accessibility of the infrastructure used for charging electric vehicles. Various different kinds of EV charging cards do exist, catering to a diverse range of end customer requirements and market needs. Ranging from home charging, to company charging, fleet management and public charging, NFC-based smartcards can cater to various different use cases. • Residential and at-home personal cards These EV charging cards are catering to individual end users who want to access their EV charger from their single-family home, multi-family home, apartment building, or multi-tenant building. • Public personal cards These EV charging cards are fulfilling EV driver´s requirements who charge their car across various public chargers located in public charging networks. These can be chargers along roads, highways, cities, shopping centers, public buildings, and more. We can distinguish further into network-specific EV charging cards and universal EV charging cards. Network-specific EV charging cards work in one EV charging network that´s served by one CPO (Charge Point Operator), whereas universal EV charging cards work in many EV charging networks which are served by many CPOs. The later scenario is also called EV Roaming. EV Roaming essentially connects multiple eMSPs (Electro Mobility Service Providers) with multiple CPOs. By connecting eMSPs and CPOs, the EV charging network coverage can be extended, so that users can charge their EV in a variety of chargers from various different networks, which are served and operated by several different CPOs. Universal EV charging cards that support EV Roaming are highly convenient, offering the greatest possible flexibility for the EV driver. By gaining access to various different charging networks inside one country and internationally makes personal EV charging cards invaluable for navigating in the EV world.

More details: https://www.nxp.com/docs/en/application-note/AN14223.pdf