Hierarchical Wallet Key Derivation for Offline Secure Communication

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Solution Overview

Problem

Existing secure communication methods, such as identity-based cryptography, require significant memory storage for public keys and rely on a centralized trusted authority, which is a security risk.

Innovation Solution

A method using a deterministic hierarchical wallet with asymmetric master keys, where identifiers and encryption keys are deterministically derived, allowing secure communication with minimal memory storage and offline configuration, using a decentralized approach.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If identity-based cryptography is used to simplify key management, then each device can store only identifiers in memory, but a centralized trusted authority is required which creates a security vulnerability

Engineering Contradiction:
Improvekey management complexityVSAvoidsecurity vulnerability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent extracts the centralized trusted authority from the system by implementing a decentralized key derivation mechanism where each device independently generates its own key pair and derives identifiers, eliminating the security vulnerability while maintaining simplified key management

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the key management function by allowing each device to independently manage its own key pair and derive identifiers locally, rather than relying on a centralized authority, thus distributing the security function across multiple independent units

Inventive Principle:
Principle #1Segmentation

2Reliability

If public key infrastructure is used to secure communications, then security is maintained, but each device must distribute and store numerous public keys increasing memory requirements

Engineering Contradiction:
Improvecommunication securityVSAvoidmemory storage volume
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent makes the identifier multi-functional by using it both as a unique device identifier and as a public key for cryptographic operations, eliminating the need to store separate public keys while maintaining security

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

Solution Approach 2:

The patent merges the identifier and public key into a single cryptographic element, where the identifier serves dual purposes as both a unique device label and a public key for encryption and verification operations

Inventive Principle:
Principle #5Merging (Combining)

3Ease of operation

If a centralized trusted authority generates private keys for user devices, then key management is simplified, but the authority becomes a major point of compromise for security

Engineering Contradiction:
Improvekey management easeVSAvoidsecurity compromise risk
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent implements self-service key management where each device independently generates its own private key and derives its own identifier, eliminating the need for a centralized authority and thus the associated security risk while maintaining operational simplicity

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4629558A1Secure communication method and device using a deterministically derived identifier
Publication Date: 2025.10.08 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP4629558A1 patent drawingFigure 1~2
  • EP4629558A1 patent drawingFigure 3~4
  • EP4629558A1 patent drawingFigure 5

AI summary

The invention relates to a method for secure communication between a sending peer (3) and a receiving peer (4) and involving an external actor (2) having a deterministic hierarchical wallet (1) comprising a pair of master keys kmaster and Kmaster. The external actor (2) configures (104) the receiving peer (4) by recording in its electronic memory an IBE decryption key aDKey[Idj,kmaster]. The external actor (2) configures (105) the sending peer (3) by recording in its electronic memory an index j of the receiving peer and the master public key Kmaster. The sending peer (3) determines (106) in a deterministic manner an identifier Idj of the receiving peer, then calculates (107) an IBE encryption key aCKey[Idj,Kmaster]. The sending peer (3) encrypts (108) a message (60) using the key aCKey[Idj, Kmaster] and sends (109) the encrypted message (61) to the receiving peer (4). The receiving peer (4) decrypts (110) the message using the key aDKey[Idj, kmaster].