Cryptographic Verification System for DFA Attack Detection

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Solution Overview

Problem

Electronic entities with encrypted access, such as microcircuit cards, are vulnerable to differential fault analysis (DFA) attacks that disrupt the execution of cryptographic algorithms, allowing attackers to recover the secret key by inducing errors during the key generation process.

Innovation Solution

Implementing a method that stores intermediate results or sub-keys and repeats the key generation process to recalculate and compare results, prohibiting the broadcasting of encrypted messages if differences are detected, effectively preventing DFA attacks by ensuring identical results if no error occurred.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cryptographic algorithms (AES/DES) are implemented in microcircuit cards, then secure encrypted access is provided, but the system becomes vulnerable to DFA attacks that can recover secret keys

Engineering Contradiction:

ImprovesecurityVSAvoidDFA attack vulnerability

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by storing intermediate results or sub-keys before the cryptographic algorithm completes its execution. This pre-stored data serves as a reference point for later verification, allowing the system to detect DFA attacks that occur during algorithm execution by comparing recalculated values against these pre-stored values.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by recalculating intermediate results or sub-keys after the cryptographic algorithm executes and comparing them against the pre-stored values. This feedback mechanism detects discrepancies caused by DFA attacks, enabling the system to identify when its cryptographic operations have been compromised and take appropriate security measures.

Inventive Principle:

Principle #23Feedback

2Reliability

If intermediate results are stored and the iterative process is repeated for verification, then DFA attack detection capability is improved, but computational time and processing overhead increase

Engineering Contradiction:

ImproveDFA attack detectionVSAvoidverification processing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies partial action by storing only specific intermediate results or sub-keys at critical points in the cryptographic algorithm's iterative process, rather than storing all intermediate values. The verification process recalculates only these selected values to check for DFA attacks, rather than re-executing the entire cryptographic algorithm, thus reducing the time overhead while maintaining effective attack detection.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS7796750B2Method for making secure an electronic entity with encrypted access

Publication Date: 2010.09.14 IDEMIA FRANCE SAS

AI summary

A method for protecting an electronic entity with encrypted access, against DFA (Differential Fault Analysis) attacks which includes: storing the result of a selected step (Rm, Kn) of an iterative process forming part of the cryptographic algorithm and in performing once more at least part of the steps of the iterative process up to a new computation of a result corresponding to the one which has been stored, comparing the two results and denying distribution of an encrypted message (MC) if they are different.