Imagine driving down the highway, your favorite song blaring over your car’s state-of-the-art infotainment system. But what if that same system was an entry point for a cyberattack? While this scenario may sound like science fiction, the evolving landscape of automotive technology has made it — however far-fetched — a possibility that engineers and security experts can’t ignore.
Armed with a specially crafted signal, a hostile actor could infiltrate your vehicle’s system by altering the software image on the phase-locked loop (PLL) chip controlling your car’s audio timing. By altering the software image on this tiny but crucial peripheral device, the hacker could potentially disrupt your music and — even worse — critical vehicle communications.
While this scenario remains largely theoretical, it underscores a growing concern in the automotive industry: As our vehicles become more connected and sophisticated, even the most unsuspecting components can become potential security vulnerabilities.
In our ongoing exploration of PLLs in automotive audio systems, we’ve covered the basics and delved into their interaction with precision timing protocols. Now, we focus on a critical aspect taking on greater importance in our increasingly connected world: embedded memory security for peripheral devices.
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The Evolution of Automotive PLLs
As vehicle systems become more sophisticated, so too do the phase-locked loops used as peripheral devices to help synchronize their various components. Transitioning from traditional PLLs to more advanced chips brings benefits and new challenges. The main challenge with modern higher-speed PLLs is that they can run at much higher frequencies, so more advanced design techniques should be considered.
ZL30253 Vs. CS2000 Microchips
The ZL30253, for our specific project, offers several advantages over its predecessor, the CS2000:
- Higher maximum frequency (1.03 GHz vs. 75 MHz)
- Differential input capability
- Broader voltage range (1.8V-3.3V)
- Built-in EEPROM
- Frame syncing ability
These features allow for more precise timing control and better synchronization with other devices. However, with increased system complexity comes new embedded security considerations.
Peripheral Device Security Implications
Introducing built-in EEPROM in modern PLLs like the ZL30253 has raised general concerns among hardware engineers for embedded memory for peripheral devices. While this feature allows for easier configuration and potentially faster boot times, it also introduces new vulnerabilities concerning the integrity of the EEPROM. There are two main risks:
- Bitrot: The EEPROM could degrade over time, leading to corrupted configuration data.
- Malicious interference: Theoretically, an attacker could attempt to alter the EEPROM contents.
Either scenario could result in a loss of synchronization in the peripheral device, potentially causing systemwide issues. In the context of our phase-locked loop application — an automotive audio system — this could lead to a complete loss of audio functionality.
Unfortunately, a compromised PLL doesn’t just affect audio quality. Peripheral device security has far-reaching consequences depending on its role in the system architecture. If the peripheral is used for a specific subcircuit, altered settings could skew the performance of that particular system. If the device drives the entire system, on the other hand, significant changes to its configuration could render the whole system nonfunctional until a firmware update is applied.
While the battle to balance design simplicity with modern security features continues raging, our work on a recent project revealed some potential resolutions.
Potential Security Solutions for Peripherals with Embedded Memory
No one-size-fits-all solution to embedded memory security for peripheral devices exists, but we’ve found several approaches can mitigate risks.
- Centralized configuration: Instead of relying on the peripheral device’s internal EEPROM, have the central MCU/CPU load configuration settings after each boot. This approach ensures that the peripherals, like PLL, are always in a known configuration.
- Independent monitoring: Use an external controller with an independent clock to perform rough checks of the peripheral device output, ensuring ongoing functionality.
- Robust hardware design: The hardware should be designed in a way that only one central controller can reprogram peripherals. Authentication peripherals, such as unique hardware IDs, can be used with encryption to validate any over-the-air firmware updates.
- Secure boot and encryption: Implement industry-standard security protocols like secure boot processes and encryption of critical data.
- Peripheral redundancy: Incorporate backup or redundant peripherals to maintain system functionality in case of primary device failure.
As is always the case, adding security features can increase system complexity, which — in turn — can introduce new vulnerabilities if not managed carefully.
Accelerating Toward a Secure Audio Landscape
As vehicles become more connected — supporting features like over-the-air updates and vehicle-to-everything (V2X) communication — robust security measures command more importance. While PLLs might seem like a small part of this picture, peripheral devices represent a critical component in the overall security architecture.
The automotive industry is increasingly adopting a “security by design” approach, building security considerations into every component from the ground up. This holistic view of security helps create resilient, trustworthy vehicle systems. But embedded memory security in peripheral devices — like PLLs in cars — represents just a small part of the broader challenges facing every industry as we move into an increasingly digital, connected future.
Successfully navigating this complex landscape demands collaboration between hardware and software teams — along with a commitment to ongoing learning and adaptation — to create technology systems that are not just high-performing but also secure and resilient.
With our extensive experience, we can help address your embedded memory security challenges. Our team of experts looks forward to discussing your project requirements and providing time and budget estimates to get your project started — connect with us today!