Encryption Algorithm Operation Shuffling for Side Channel Resistance

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Solution Overview

Problem

Existing encryption algorithms, such as AES, are vulnerable to side channel and template attacks due to predictable patterns, which can be anticipated by malicious actors, necessitating enhanced resistance mechanisms.

Innovation Solution

The method involves shuffling operations within each round of the encryption algorithm, using a combination of substitution and permutation operations on a matrix of sensitive data, with cyclic shift-row operations and 8-bit substitution boxes, and deriving unique round keys, while employing status flags and buffers to manage and mix these operations unpredictably.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If standard AES algorithm operations are used, then encryption speed and simplicity are maintained, but the system becomes vulnerable to side channel and template attacks due to predictable patterns

Engineering Contradiction:
Improveresistance to side channel attacksVSAvoidoperation shuffling mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the operation sequence variable rather than fixed. Different execution orders are generated dynamically based on control parameters, preventing attackers from predicting the sequence of operations. This dynamic shuffling of substitution, permutation, and key addition operations across different rounds makes template attacks ineffective while maintaining the core AES functionality.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent combines multiple AES operations (substitution, permutation, key addition) with a control mechanism that manages their execution order. This composite structure integrates the standard AES operations with an additional control layer that shuffles their sequence, creating a hybrid system that maintains cryptographic strength while adding resistance to side channel and template attacks.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If operation shuffling is implemented to prevent template attacks, then security against malicious attacks is improved, but the complexity of the encryption process increases

Engineering Contradiction:
Improveprotection against template attacksVSAvoidoperation management structure
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent segments the AES encryption process into distinct operational components (substitution operations, permutation operations, key addition operations) that can be independently controlled and shuffled. By dividing the encryption process into these manageable segments, the system can randomize their execution order without requiring complete restructuring of the entire encryption algorithm, thus managing complexity while enhancing security.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the execution parameters of the AES algorithm by introducing variable operation sequences instead of fixed sequences. Control parameters determine the shuffling pattern, allowing the system to adapt the operation order without changing the fundamental cryptographic operations. This parameter-based control enables flexible security enhancement while keeping the implementation manageable.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3069461B1Method to securely encrypt a sensitive data
Publication Date: 2018.09.05 THALES DIS FRANCE SA
  • EP3069461B1 patent drawingFigure 1~2B
  • EP3069461B1 patent drawingFigure 2C~3E
  • EP3069461B1 patent drawingFigure 4A~4C

AI summary

The present invention relates to a method to encrypt a sensitive data constituted by words (Wi) using a ciphering algorithm, said ciphering algorithm having at least one round (n) comprising at least two operations (Ok or Oki) to be executed on all words (Wi), said operations (Ok or Oki) being switchable thanks to operation status flags (SF), additional buffer (B) and additional operations (AdO), said method comprising the steps of: - randomly determining (S1) an order (RND) for said operations (Ok or Oki) in each round (n); - applying (S2) operations (Ok or Oki) on all words (Wi) of the sensitive data according to the determined order (RND) in each round (n); - performing (S3) additional operations (AdO) in case of need; - updating (S4) operation status flags (SF) and additional buffer (B) depending on the application of the operations (Ok or Oki).