Cryptographic Key Domain Validation via Fingerprint Storage

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Solution Overview

Problem

Current methods for validating cryptographic keys in public key cryptography are energy-intensive and time-consuming, leading to inefficiencies and user experience degradation, especially in scenarios like passport control where key reuse and key expiration complicate domain validation processes.

Innovation Solution

A method that calculates a unique identifier for a cryptographic domain and stores it in memory only after successful validation, allowing subsequent key usage without revalidation unless the identifier is not found, thus reducing redundant validations and memory storage needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the electronic device validates the domain of each received cryptographic key through complex mathematical calculations, then the reliability of key usage is ensured, but the processing time and energy consumption increase significantly

Engineering Contradiction:

Improvekey validation reliabilityVSAvoidvalidation processing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-calculating and storing a fingerprint of the domain parameters before actual key validation is needed. When a cryptographic key is received, the system only needs to compare the fingerprint rather than performing full domain validation, thus resolving the contradiction between ensuring reliability and reducing processing time

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent creates a simplified copy (fingerprint) of the domain parameters that captures the essential validation information without containing all the mathematical details. This fingerprint copy enables rapid comparison and validation decisions, eliminating the need for time-consuming full domain validation while maintaining security requirements

Inventive Principle:

Principle #26Copying

2Reliability

If the electronic device performs full domain validation for each new cryptographic key, then security is maintained, but energy consumption increases

Engineering Contradiction:

Improvecryptographic securityVSAvoidvalidation energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent transforms the domain validation problem from verifying complex mathematical relationships to comparing simplified fingerprint parameters. This parameter transformation reduces the computational complexity and energy requirements while preserving the security-critical validation functionality

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the device stores validated keys in memory for reuse, then processing speed improves for repeated keys, but memory storage requirements increase

Engineering Contradiction:

Improvekey processing speedVSAvoidmemory storage capacity

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent stores only the essential fingerprint information of validated domains rather than complete key materials or full domain parameters. This selective storage of critical identification data enables rapid matching and reuse decisions while minimizing memory consumption

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent extracts only the necessary identifying information (fingerprint) from the full domain parameters for storage purposes. This extraction approach separates the essential validation identifier from the complete mathematical description, enabling efficient storage and retrieval without retaining unnecessary data

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentEP3836480A1Method and device for determining the possibility of using a cryptographic key for performing a cryptographic operation

Publication Date: 2021.06.16 IDEMIA FRANCE SAS

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AI summary

A method and device for determining the feasibility of using a cryptographic key to perform a cryptographic operation. The cryptographic key is defined within a domain containing parameters.The process is implemented by a first electronic device integrated into an identification document and comprises the following steps: - obtaining the key from a second electronic device; - obtaining a unique identifier for the domain, this unique identifier being calculated from the parameters of the domain; - searching for the unique identifier in a list containing validated domain identifiers, this list being saved in a memory of the first device; - if and only if the unique identifier is not found in the list, -- validation of the domain; and -- recording of the unique identifier in the list only if the validation is successful; the key can be used to perform the cryptographic operation if and only if the unique identifier is recorded in the list.