Current Flattening Circuit for Power Side-Channel Attack Mitigation

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Solution Overview

Problem

Side-channel attacks, such as differential power analysis, exploit power consumption information from secure hardware, posing a risk to cryptographic operations by revealing sensitive information through power fluctuations back to circuit package pins.

Innovation Solution

A current flattening circuit is implemented with a constant current source, a high bandwidth current regulator, and a randomizer to generate a regulated current that mirrors load current variations, reducing signal-to-noise ratios and preventing power fluctuations from propagating back to the power supply pins, thereby enhancing security against side-channel attacks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a current flattening circuit is implemented to prevent power fluctuations from propagating back to power supply pins, then security against side-channel attacks is improved, but device complexity increases

Engineering Contradiction:

Improvesecurity against side-channel attacksVSAvoidcircuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A current regulator circuit is introduced as an intermediary between the load and power supply pins. This regulator includes a control input that receives a flattening signal, a control element that adjusts its conductivity based on the control input, and a shunt element that diverts current. The intermediary regulator prevents power fluctuations from propagating back to the power supply pins while maintaining proper current delivery to the load, thus improving security without requiring complete circuit redesign.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The current regulator dynamically changes its electrical parameters (conductivity, current division ratio) based on the flattening signal received at the control input. By adjusting the conductivity of the control element and the current division through the shunt element in response to detected power fluctuations, the circuit adapts its behavior to flatten the power consumption profile, reducing side-channel attack vulnerability while maintaining operational functionality.

Inventive Principle:

Principle #35Parameter changes

2Difficulty of detecting and measuring

If noise is added to the power supply current to obscure sensitive information, then detection difficulty for adversaries increases, but signal-to-noise ratio deteriorates

Engineering Contradiction:

Improvedetection difficulty for power consumption analysisVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Difficulty of detecting and measuringVSLoss of information

Solution Approach 1:

The current regulator applies different current characteristics to different parts of the circuit. The shunt element diverts a portion of the current with flattened characteristics while the main load current maintains its functional requirements. This local differentiation allows the power supply path to have noise-flattened quality for security purposes while the load receives appropriate current quality for operational purposes, preventing information leakage without compromising functionality.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11594962B2Techniques to improve current regulator capability to protect the secured circuit from power side channel attack

Publication Date: 2023.02.28 NVIDIA CORP

AI summary

This disclosure relates to current flattening circuits for an electrical load. The current flattening circuits incorporate randomize various parameters to add noise onto the supply current. This added noise may act to reduce the signal to noise ratio in the supply current, increasing the difficulty of identifying a computational artifact signal from power rail noise.