ISO 15118

Security Alert

ISO 15118 has 8 known vulnerabilities as of the latest security assessment.

Overview

ISO 15118 is an international standard that defines a vehicle-to-grid (V2G) communication interface for bidirectional charging and discharging of electric vehicles. It enables advanced communication between electric vehicles (EVs) and charging stations, facilitating features like Plug & Charge (PnC), bidirectional power transfer, and smart charging.

The standard was developed by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) to create a globally accepted protocol for EV-to-charging station communication. It goes beyond basic charging control to enable a seamless and secure charging experience while supporting grid integration of electric vehicles.

ISO 15118 Architecture: Communication between EV, Charging Station, and Backend Systems

ISO 15118 Standard Parts

ISO 15118 is divided into multiple parts, each addressing different aspects of the vehicle-to-grid communication interface:

Part	Title	Description
ISO 15118-1	General information and use-case definition	Defines the use cases and overall requirements for the standard
ISO 15118-2	Network and application protocol requirements	Specifies the technical details of the communication protocol (first generation)
ISO 15118-3	Physical and data link layer requirements	Defines the physical and data link layer requirements
ISO 15118-4	Network and application protocol conformance test	Provides conformance tests for the protocol
ISO 15118-8	Physical layer and data link layer requirements for wireless communication	Specifies wireless communication requirements
ISO 15118-20	2nd generation network and application protocol requirements	Defines the second generation of the protocol with enhanced features

Key Differences Between ISO 15118-2 and ISO 15118-20

Enhanced Bidirectional Charging: ISO 15118-20 provides more comprehensive support for bidirectional power transfer, enabling advanced V2G applications.
Wireless Power Transfer: ISO 15118-20 includes improved support for wireless charging scenarios.
Multiple Contract Handling: ISO 15118-20 allows for handling multiple charging contracts within a single EV.
Improved Security: ISO 15118-20 enhances the security mechanisms and certificate handling.
Optimized Message Structure: ISO 15118-20 uses a more efficient message structure and encoding.

Communication Protocol

ISO 15118 defines a communication protocol stack that enables secure and reliable communication between the Electric Vehicle Communication Controller (EVCC) and the Supply Equipment Communication Controller (SECC).

Protocol Layers

The ISO 15118 communication stack follows the OSI model and consists of the following layers:

Layer	Protocols	Description
Application Layer	V2G Application Protocol	Handles the application-specific messages and logic
Transport Layer	TCP/IP, TLS	Provides reliable, secure data transport
Network Layer	IPv6	Handles addressing and routing
Data Link Layer	IEEE 802.3, HomePlug GreenPHY, IEEE 802.11n	Manages data framing and media access
Physical Layer	PLC (Power Line Communication), Wi-Fi	Handles the physical transmission of data

Message Exchange

ISO 15118 uses XML-based messages for communication between the EV and the charging station. The message exchange follows a request-response pattern, with the EV typically initiating the communication.

Initial message exchange to establish a charging session

<!-- Request from EV to Charging Station -->
<v2g:V2G_Message>
  <v2g:Header>
    <v2g:SessionID>1234567890ABCDEF</v2g:SessionID>
  </v2g:Header>
  <v2g:Body>
    <v2g:SessionSetupReq>
      <v2g:EVCCID>1A2B3C4D5E6F</v2g:EVCCID>
    </v2g:SessionSetupReq>
  </v2g:Body>
</v2g:V2G_Message>

<!-- Response from Charging Station to EV -->
<v2g:V2G_Message>
  <v2g:Header>
    <v2g:SessionID>1234567890ABCDEF</v2g:SessionID>
  </v2g:Header>
  <v2g:Body>
    <v2g:SessionSetupRes>
      <v2g:ResponseCode>OK</v2g:ResponseCode>
      <v2g:EVSEID>DE*ABC*E12345</v2g:EVSEID>
      <v2g:TimeStamp>2023-05-06T10:00:00Z</v2g:TimeStamp>
    </v2g:SessionSetupRes>
  </v2g:Body>
</v2g:V2G_Message>

Implementation Considerations

Implementing ISO 15118 in EVs and charging infrastructure requires careful consideration of several factors:

PKI Infrastructure

A robust Public Key Infrastructure (PKI) is essential for ISO 15118, particularly for Plug & Charge functionality. This requires:

Establishment of trusted Certificate Authorities (CAs)
Secure certificate provisioning processes
Certificate revocation mechanisms
Regular certificate renewal procedures
Secure storage of private keys in both EVs and charging stations

Hardware Requirements

ISO 15118 implementation requires specific hardware capabilities:

Power Line Communication (PLC): HomePlug GreenPHY is typically used for the physical layer communication.
Secure Element: Hardware security modules for storing private keys and performing cryptographic operations.
Processing Power: Sufficient computational resources for handling XML message processing and cryptographic operations.
Memory: Adequate storage for certificates and communication buffers.

Testing and Certification

Ensuring interoperability and compliance with ISO 15118 requires thorough testing:

Conformance testing against the ISO 15118-4 test specifications
Interoperability testing with multiple vendors
Security testing to identify potential vulnerabilities
Field testing in real-world conditions
Certification through recognized testing laboratories

ISO 15118 vs. Other Protocols

ISO 15118 complements other protocols in the EV charging ecosystem, each serving different purposes:

Protocol	Purpose	Relationship to ISO 15118
ISO 15118	Communication between EVs and charging stations	-
OCPP	Communication between charging stations and management systems	Complementary to ISO 15118, operates at a higher level
OCPI	Communication between charging networks for roaming	Complementary to ISO 15118, operates at a higher level
IEC 61851	Basic charging control using PWM signaling	Simpler alternative to ISO 15118 for basic charging

Future Developments

ISO 15118 continues to evolve to meet the changing needs of the EV charging ecosystem:

ISO 15118-20: The latest version with enhanced bidirectional charging capabilities and wireless charging support.
Wireless Communication: Expanding support for Wi-Fi and other wireless technologies beyond PLC.
Grid Integration: Enhanced features for vehicle-to-grid services and grid balancing.
Interoperability: Improved compatibility with other standards and protocols.
Security Enhancements: Ongoing improvements to address emerging security threats.