Nonlinear LDO Cascades for Crypto Side-Channel Leakage Suppression
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Solution Overview
Problem
Conventional power regulator-based techniques provide insufficient resistance to side-channel attacks in the frequency-domain, as they induce linear transformations that can be easily exposed through methods like fast Fourier transform, failing to effectively boost the minimum traces to disclose (MTD) in cryptographic systems.
Innovation Solution
A cascaded implementation of a non-linear low-dropout regulator (NL-LDO) combined with cryptographic engines and arithmetic transformations, which randomizes control loop parameters and provides a wide-dynamic-range, high-bandwidth response to mask power consumption variations, achieving more than five orders of magnitude improvement in both time and frequency-domain MTD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If non-linear low-dropout regulator with arithmetic transformations is implemented, then frequency-domain MTD is improved, but device complexity increases
Solution Approach 1:
The patent merges the non-linear low-dropout regulator with the cryptographic engine into an integrated system. The power regulator and cryptographic operations are combined in a way that the non-linear power delivery characteristics are directly coupled with the arithmetic transformations, creating a unified SCA-resistant cryptographic system that reduces overall complexity.
Solution Approach 2:
The non-linear low-dropout regulator serves multiple functions: it provides standard voltage regulation, introduces non-linear transformations for SCA resistance, and works synergistically with arithmetic transformations in the cryptographic engine. This multi-functionality reduces the need for separate dedicated components.
2Object-generated harmful factors
If non-linear low-dropout regulator is used, then power consumption masking is improved, but area overhead increases
Solution Approach 1:
The patent changes the operational parameters of the power regulator by introducing non-linear control characteristics. The non-linear error amplifier and non-linear transfer function modify how the regulator responds to load changes, effectively masking power consumption variations associated with cryptographic operations without requiring substantial area increases.
Data Source
AI summary
Apparatus and method for resisting side-channel attacks on cryptographic engines are described herein. An apparatus embodiment includes a cryptographic block coupled to a non-linear low-dropout voltage regulator (NL-LDO). The NL-LDO includes a scalable power train to provide a variable load current to the cryptographic block, randomization circuitry to generate randomized values for setting a plurality of parameters, and a controller to adjust the variable load current provided to the cryptographic block based on the parameters and the current voltage of the cryptographic block. The controller to cause a decrease in the variable load current when the current voltage is above a high voltage threshold, an increase in the variable load current when the current voltage is below a low voltage threshold; and a maximization of the variable load current when the current voltage is below an undervoltage threshold. The cryptographic block may be implemented with arithmetic transformations.