Masking Data in Electronic Circuits Against Side-Channel Attacks

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Solution Overview

Problem

Existing methods for masking data in electronic circuits are vulnerable to side-channel attacks, particularly Differential Power Analysis (DPA), as the detection of random masking quantities can reveal correlations between encrypted data and secret keys, and current countermeasures are either costly in terms of integrated circuit area or increase the complexity of operations.

Innovation Solution

A method using multiple, randomly ordered and sized parts of a mask applied successively for both masking and unmasking operations, where the mask is divided into parts that are combined using Exclusive-OR operations, making it difficult for attackers to determine the key by monitoring state transitions in the register.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single random mask is used for masking operations, then the security against DPA attacks is improved, but the vulnerability to detection of the random quantity increases

Engineering Contradiction:
Improvesecurity against DPA attacksVSAvoiddetection of random quantity
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent divides the random mask into multiple parts (first mask part and second mask part) that are applied successively. This segmentation prevents the detection of individual mask components while maintaining the masking security, as each part is applied at a different stage of the calculation process.

Inventive Principle:
Principle #1Segmentation

2Difficulty of detecting and measuring

If two registers are used to store intermediate results, then the detection difficulty is improved, but the integrated circuit area increases

Engineering Contradiction:
Improvedetection difficultyVSAvoidintegrated circuit area
Core Design Contradiction:
Difficulty of detecting and measuringVSArea of stationary object

Solution Approach 1:

The patent segments the masking operation into multiple parts applied successively, which allows the use of a single register to store intermediate results. This segmentation approach reduces the need for additional registers while maintaining detection difficulty, thereby reducing the integrated circuit area.

Inventive Principle:
Principle #1Segmentation

3Reliability

If the mask is applied part by part, then the security is improved, but the operation complexity increases

Engineering Contradiction:
ImprovesecurityVSAvoidoperation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies the mask in segments (first mask part, second mask part) at different stages of the calculation. This segmentation improves security by preventing correlation detection while the sequential application follows a structured process that manages operation complexity through clear temporal separation of masking steps.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2020773B1Masking of a data item in a calculation
Publication Date: 2016.04.13 STMICROELECTRONICS SA
  • EP2020773B1 patent drawingFigure 1~3
  • EP2020773B1 patent drawingFigure 4~5
  • EP2020773B1 patent drawingFigure 6~7

AI summary

The invention relates to a method and circuit for encrypting or decrypting data (PT, CT) by a key (K) using at least one variable (V) stored in a memory element and updated by successive operations, the variable being masked by at least one first random mask applied before use of the key, then unmasked by at least one second mask applied after use of the key, at least one of the masks being divisible into several parts (R1, R2, R3, R4) applied successively to the variable and which combined represent the other mask.