How to use a secure IC to maintain the integrity of dc metering data

Direct current (dc) metering is essential in industry segments as varied as data centers, communications, transportation, industrial equipment, and renewable energy. The proliferation of dc circuits, especially in applications such as electric vehicle (EV) charging stations, has led to an increased demand for reliable and trustworthy dc metering technology. Unlike ac metering, which fails to account for losses that occur in the process of ac-to-dc conversion, dc metering ensures the accurate measurement of actual energy consumed.

Ensuring the credibility and integrity of dc metering data, however, presents a substantial challenge. As global standards and regulations evolve to standardize metering outputs, the need for authentic and secure measurements becomes crucial. This highlights the important role that secure ICs for authentication play in ensuring the trustworthiness of dc metering applications.

The importance of reliable dc metering

Dc metering plays an essential role in applications such as dc fast charging at level 3 and above. In these settings, end users need to pay for the precise amount of energy they receive. Ac metering might not provide accurate results because of the losses incurred during ac-dc conversion. Therefore dc metering is essential for billing transparency and fairness.

Global standards, such as the German Eichrecht standard, are being developed to ensure that dc metering measurements are authentic and trustworthy. These standards require end users to have the means to validate the authenticity of energy measurements: secure ICs can perform this role.

Challenges in ensuring dc metering security

Dc metering systems typically include a microcontroller responsible for logic operations, an LCD display, and communications capability. While these systems often use MCUs from reputable suppliers, the security function is often implemented in software. Software-based security, however, can expose dc meters to vulnerabilities that could compromise the credibility of the measurements.

Secure ICs: a solution for reliable dc metering

Microchip offers a wide range of solutions, including reference designs, that cater to vertical markets in which dc metering is vital. The TA100, ATECC608 and ECC204 specifically address the security challenges in dc metering. These devices provide robust, hardware-level protection for private keys, and support ECC P256 ECDSA sign operations in hardware. By drawing on the Microchip CryptoAuthentication™ library, dc metering equipment vendors can efficiently implement secure, JSON-encrypted data signing.

OCMF: ensuring authenticity and integrity

In the context of dc metering, the Open Charging Metering Format (OCMF) often comes into play, particularly in reference to the Eichrecht standard in Germany. OCMF is a JSON format which includes energy measurements and a valid ECC signature. This format allows end users to verify the authenticity of measurements by using the corresponding public key as shown in Figure 1. Additionally, the German Eichrecht standard mandates that dc meters include a small display accessible to users for transparency and validation.

Fig. 1: The process flow for authentication of a dc meter’s measurement outputs

Secure IC devices such as the TA100, ATECC608 or ECC204 ensure that private keys are securely stored in hardware, making it difficult for hackers to compromise the integrity of dc metering data. Implementing JSON data signing with these devices is straightforward, thanks to the high-level application programming interfaces provided in the CryptoAuthentication library and Microchip’s secure key provisioning service.

Conclusion

Secure ICs provide a robust solution for safeguarding private keys and ensuring the authenticity and integrity of dc metering measurements. By embracing hardware-level security, dc metering equipment vendors can meet evolving standards and regulations while offering end users transparent and trustworthy billing.