Information (Aug 2024)
A Methodology to Distribute On-Chip Voltage Regulators to Improve the Security of Hardware Masking
Abstract
Hardware masking is used to protect against side-channel attacks by splitting sensitive information into different parts, called hardware masking shares. Ideally, a side-channel attack would only work if all these parts were completely independent. But in real-world VLSI implementations, things are not perfect. Information from a hardware masking share can leak to another, making it possible for side-channel attacks to succeed without needing data from every hardware masking share. The theoretically supposed independence of these shares often does not hold up in practice. The effectiveness of hardware masking is reduced because of the parasitic impedance that stems from power delivery networks or the internal structure of the integrated circuit. When the coupling effect and noise spread among the hardware masking shares powered by the same power delivery network, side-channel attacks can be carried out with fewer measurements. To address this, we propose a new method of distributing on-chip voltage regulators to improve hardware masking security. The benefits of distributed on-chip voltage regulators are evident. Placing the regulators close to the load minimizes power loss due to resistive losses in the power delivery network. Localized regulation allows for more efficient adjustments to the varying power demands of different chip sections, improving overall power efficiency. Additionally, distributed regulators can quickly respond to power demand changes, maintaining stable voltage levels for high-performance circuits, leading to improved control over noise. We introduce a new DLDO voltage regulator that uses random clocking and randomizing limit cycle oscillations to enhance security. Our simulations show that with these distributed DLDO regulators, the t-test value can be as low as 2.019, and typically, a circuit with a t-test value below 4.5 is considered secure.
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