Quantum Key Sharing Architecture for Secure Multi-Path Distribution

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Solution Overview

Problem

Existing quantum cryptography systems face limitations in communication distance due to the use of optical cables and high costs associated with expensive BB84QKD devices, while also being vulnerable to key interception over the Internet, known as the 'last mile problem'.

Innovation Solution

A cryptographic communication system utilizing CVQKD devices for cost-effective key distribution and BB84QKD devices for relaying, combined with multiple paths to disperse cryptographic keys, ensuring security through a nested structure and mesh-type quantum cryptographic distribution networks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If BB84QKD devices are used for quantum key distribution, then communication security is improved, but device cost increases significantly

Engineering Contradiction:

Improvecommunication securityVSAvoiddevice cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The system segments the quantum key distribution network into different functional components: CVQKD devices for cost-effective key generation and BB84QKD devices for secure relaying. This segmentation allows each component to be optimized for its specific function, reducing overall system cost while maintaining security.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces CVQKD devices as intermediary components that can generate cryptographic keys at lower cost, while BB84QKD devices serve as mediators for secure relaying over long distances. This intermediary approach allows the system to achieve both cost reduction and security maintenance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If optical cables are used for quantum key distribution, then key distribution security is improved, but communication distance is limited

Engineering Contradiction:

Improvekey distribution securityVSAvoidcommunication distance

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent employs BB84QKD devices as intermediary relaying nodes that can extend the communication distance by establishing quantum key distribution over multiple segments. Each segment maintains security through optical cables while the relay nodes enable long-distance communication through key sharing.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system transitions from a single-point key distribution model to a multi-node relay model, adding a dimensional aspect to the communication architecture. This allows the system to overcome the direct distance limitation by creating a distributed key distribution framework.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If cryptographic keys are delivered through the Internet, then cost is reduced, but key interception risk increases

Engineering Contradiction:

ImprovecostVSAvoidkey interception risk

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent segments the key delivery path into quantum channels for key generation and classical channels for key distribution. By separating these functions and using multiple paths, the system reduces the risk of complete key interception while maintaining cost-effectiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system implements a nested structure where multiple cryptographic key transmission paths are organized within a hierarchical framework. This nested architecture ensures that even if one path is compromised, other nested paths remain secure, mitigating the impact of key interception.

Inventive Principle:

Principle #7Nested doll (Nesting)

4Reliability

If multiple paths are used to disperse cryptographic keys, then security against key interception is improved, but system complexity increases

Engineering Contradiction:

Improvesecurity against key interceptionVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the key distribution system into standardized modules (CVQKD devices, BB84QKD devices, relay nodes) that can be independently configured. This modular segmentation simplifies the management of multiple paths while maintaining the security benefits of path diversity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system employs universal relay nodes and standardized interface protocols that can function across multiple paths and network configurations. This universality reduces the complexity of managing diverse components while enabling robust multi-path key distribution.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20250373416A1User base device, cryptographic communication system, and cryptographic communication method

Publication Date: 2025.12.04 KK TOSHIBA

AI summary

According to one embodiment, a user base device A has a cryptographic module a key sharing module. The key sharing module restores and disperses a cryptographic key used to generate the encrypted data. The key sharing module includes a quantum cryptographic communication device applicable to a plurality of front ends. The front ends are used to receive dispersed cryptographic key from different routes, and to output dispersed cryptographic key to different routes.