Hardware root of trust (HRoT) is a tamper-resistant hardware-based security foundation that enables a device to prove its identity and integrity. In EV charging infrastructure, a hardware root of trust helps protect chargers against firmware tampering, unauthorized access, and spoofed device identity, supporting a secure lifecycle from manufacturing to field operation.
What Is a Hardware Root of Trust?
A hardware root of trust is a dedicated security component (or a secure functionality embedded in a microcontroller) designed to securely store and use cryptographic secrets. It typically provides:
– Secure storage for private keys and device credentials
– A unique, non-clonable device identity
– Hardware-backed cryptographic operations (signing, verification, encryption)
– Protection against key extraction, even if the software is compromised
Common implementations include a secure element, a TPM (Trusted Platform Module), or a microcontroller with a built-in secure enclave.
Why Hardware Root of Trust Matters in EV Chargers
EV chargers are connected devices that communicate with backends via OCPP, receive OTA firmware updates, and may process billing and user-related data. A hardware root of trust strengthens:
– Secure boot, preventing the charger from running modified firmware
– Trustworthy firmware integrity validation during updates and startup
– Strong authentication to backend systems, reducing impersonation risk
– Secure storage of certificates used for encrypted communications
– Compliance with modern security expectations for critical infrastructure
For operators, HRoT reduces cybersecurity incidents that can cause downtime, fraud, or reputational damage.
How Hardware Root of Trust Works
A typical HRoT-enabled security chain looks like this:
– The device boots and verifies a cryptographic signature on the bootloader (secure boot)
– The bootloader verifies the operating firmware before execution
– Certificates and keys used for TLS are stored in protected hardware
– Firmware updates are accepted only if they are properly signed (firmware signing)
– The device can attest its software state to prove it is running trusted code (attestation)
This creates a verifiable trust chain from immutable hardware to the running firmware.
Key Capabilities Enabled by HRoT
The hardware root of trust is often the foundation for multiple security controls:
– Secure update pipeline using signed firmware packages
– Device identity and certificate provisioning at manufacturing (factory provisioning)
– Strong mutual authentication with backend services (mTLS)
– Protected key handling for payment, metering, or access control features
– Resistance to credential cloning across devices in the field
HRoT in the EV Charging Lifecycle
Security risks exist across the entire product lifecycle, not just during operation:
– Manufacturing: secure injection of keys and certificates
– Installation: preventing unauthorized configuration and role abuse
– Operation: securing OCPP sessions and remote commands
– Maintenance: controlled service access and auditability
– End-of-life: revoking credentials and securely wiping secrets
A hardware root of trust supports consistent security controls across these stages.
Limitations and Practical Considerations
While HRoT significantly improves security, it must be paired with good system design:
– HRoT protects keys, but software must still be hardened against vulnerabilities
– Processes must prevent weak provisioning and poor certificate management
– Recovery procedures are needed if keys are revoked or devices are re-provisioned
– Supply chain security matters to ensure trusted components and secure handling
Related Glossary Terms
Secure Boot
Firmware Signing
Firmware Integrity Validation
Secure Update Pipeline
OTA Firmware Updates
Device Identity
Certificate Management
Encrypted Communications
Hardware Security Module (HSM)
Charger Cybersecurity