Elliptic Curve Cryptography Obfuscation for Side-Channel Resistance

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Solution Overview

Problem

Existing cryptographic systems, particularly those using elliptic curve cryptography, face challenges in obfuscating private keys and cryptographic operations to prevent side-channel attacks, which can reveal sensitive information through observable device characteristics like power consumption and timing signatures.

Innovation Solution

The implementation of an obfuscation process that generates a randomized scalar by adding a random number to the private key and using a non-zero constant to ensure no zero bits, allowing for efficient point multiplication while maintaining the same bit length as the original key, thereby obscuring device characteristics and enhancing security.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cryptographic operations are performed without obfuscation, then computational efficiency is maintained, but device characteristics reveal sensitive information through side-channel attacks

Engineering Contradiction:
ImprovesecurityVSAvoidcomputational efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent introduces an intermediary obfuscation process that transforms the private key into a randomized form before cryptographic operations. This intermediary step masks the true private key value while preserving the mathematical properties needed for ECC operations, thereby preventing side-channel attacks without significantly impacting computational efficiency.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the parameter representation of the private key by adding random values and applying transformations. The private key is transformed from its original form into an obfuscated form with different numerical parameters but equivalent cryptographic functionality, making side-channel analysis ineffective while maintaining operational efficiency.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the private key is obfuscated with random values, then side-channel attack resistance is improved, but the bit length of the key increases

Engineering Contradiction:
ImprovesecurityVSAvoidbit length
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The patent segments the obfuscation process into distinct stages: generating random values, adding them to the private key, and performing modular arithmetic operations. Each segment processes data in controlled portions, ensuring that the final obfuscated key maintains the same bit length as the original private key while providing comprehensive security protection.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies partial obfuscation by adding random values only to specific portions of the private key representation rather than the entire key. This selective approach provides sufficient security against side-channel attacks while minimizing the increase in bit length, achieving an optimal balance between security and efficiency.

Inventive Principle:
Principle #16Partial or excessive action

3Reliability

If complex obfuscation processes are applied, then security against side-channel attacks is enhanced, but device complexity increases

Engineering Contradiction:
ImprovesecurityVSAvoidobfuscation process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements self-service obfuscation where the system automatically generates random values and performs the necessary mathematical transformations without requiring external intervention or complex management infrastructure. The obfuscation process is self-contained and integrates seamlessly with existing cryptographic operations, minimizing additional device complexity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent designs the obfuscation process to be universal and compatible with standard ECC operations. The same obfuscation mechanism can be applied to different cryptographic protocols and key sizes, reducing the need for multiple specialized components and thereby limiting the increase in device complexity.

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

Data Source

PatentUS11936768B2Obfuscating cryptographic parameters used in elliptical curve cryptography, and related systems and devices
Publication Date: 2024.03.19 MICROCHIP TECHNOLOGY INC
  • US11936768B2 patent drawing
  • US11936768B2 patent drawing
  • US11936768B2 patent drawing

AI summary

An obfuscation process is described for obfuscating a cryptographic parameter of cryptographic operations such as calculations used in elliptical curve cryptography and elliptical curve point multiplication. Such obfuscation processes may be used for obfuscating device characteristics that might otherwise disclose information about the cryptographic parameter, cryptographic operations or cryptographic operations more generally, such as information sometimes gleaned from side channel attacks and lattice attacks.