Current-Mirror Power Supply for Side-Channel Attack Resistance

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Solution Overview

Problem

Existing electronic circuit power supply devices are vulnerable to attacks that attempt to extract confidential information by measuring current variations, which can compromise the security of sensitive data such as passwords and encryption keys.

Innovation Solution

A power supply device and method that utilize a current mirror configuration with a transistor and operational amplifier to regulate the voltage of an electronic circuit, ensuring a constant current consumption and masking variations in the current consumed by the circuit, thereby protecting against attacks that rely on current measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a conventional voltage regulator is used to supply stable voltage to the electronic circuit, then the voltage stability is improved, but the current consumption varies with circuit operation making it vulnerable to attacks

Engineering Contradiction:
Improvevoltage stabilityVSAvoidcurrent measurement attacks
Core Design Contradiction:
Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces an intermediary current mirror circuit between the power supply and the electronic circuit. This current mirror acts as a mediator that replicates the circuit's current consumption pattern and feeds it back through the operational amplifier to adjust the transistor gate voltage, thereby compensating for current variations and preventing attack vectors while maintaining stable voltage supply.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a feedback mechanism where the current mirror monitors the electronic circuit's current consumption and feeds this information back through the operational amplifier to dynamically adjust the transistor's gate voltage. This closed-loop feedback system continuously compensates for current variations, maintaining constant total current consumption and eliminating the vulnerability to current measurement attacks.

Inventive Principle:
Principle #23Feedback

2Object-affected harmful factors

If the power supply device compensates for current variations to prevent attacks, then security is improved, but the device complexity increases due to additional components

Engineering Contradiction:
Improvesecurity against attacksVSAvoidpower supply device complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent makes the transistor serve multiple functions: it acts as both the main power switching element controlling voltage supply to the electronic circuit and as part of the feedback control mechanism where its gate voltage is modulated by the operational amplifier based on current mirror feedback. This multi-functionality reduces the need for separate compensation components, thereby limiting complexity increase while achieving security.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the voltage regulation function and the current compensation function into a single integrated circuit structure. The transistor, operational amplifier, and current mirror are combined into one cohesive power supply device where the feedback loop is internally integrated, rather than using separate external compensation circuits. This merging approach achieves the required security without proportionally increasing device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution effectively protects the electronic circuit against attacks by maintaining constant current consumption and reducing residual voltage variations, enhancing security and stability of the power supply.

Implementation Method 1

passing a third current in a second conductor connected to said node, a first leg of a current mirror passing the third current

Methodology Applied
Scientific EffectCurrent mirror effect:

Implementation Method 2

regulating a potential of said node by acting on a gate potential of a transistor electrically in series with a second branch of the current mirror

Methodology Applied
Scientific EffectField effect transistor control:

Implementation Method 3

an operational amplifier receives a potential difference between said node and said terminal of the second branch of said other current mirror and acts on the gate potential of said transistor

Methodology Applied
Scientific EffectOperational amplification:

Data Source

PatentEP3961344A1Power supply for electronic circuit
Publication Date: 2022.03.02 STMICROELECTRONICS (ROUSSET) SAS
  • EP3961344A1 patent drawingFigure 1
  • EP3961344A1 patent drawingFigure 2
  • EP3961344A1 patent drawingFigure 3

AI summary

This description relates to an electronic circuit power supply device (300), configured to: pass, in a first conductor (351) connected to a node (150), a first current (I1') image of a second current (I2) consumed by the electronic circuit; pass a third current (I3) in a second conductor (353) connected to said node; regulate a potential of said node to a constant value (VCST) by acting on the third current; pass a fourth constant current (I4) in a third conductor (352) connected to said node; and consume a fifth current (I5) image of the third current.