Quantum Key Distribution Key Management During QKDN Downtime

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Solution Overview

Problem

Existing quantum cryptographic communication systems face inefficiencies in managing cryptographic keys generated by key generation apparatuses within a quantum key distribution network, leading to potential key loss due to unregistered life cycle information when the QKDN management apparatus is stopped.

Innovation Solution

A quantum key distribution system with key management apparatuses that monitor the operation of the QKDN management apparatus, storing generated cryptographic keys locally when the apparatus is stopped and registering life cycle information upon resumption, allowing efficient reuse of these keys.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the QKDN management apparatus is stopped for maintenance or updates, then the system can be maintained and updated, but cryptographic keys generated during this period are lost and cannot be registered

Engineering Contradiction:

ImproveSystem maintainabilityVSAvoidCryptographic key loss

Core Design Contradiction:

Ease of manufactureVSLoss of information

Solution Approach 1:

The key management apparatus performs preliminary actions by continuously storing generated cryptographic keys in its storage unit even when the QKDN management apparatus is stopped. This ensures that keys are preserved and can be registered later when the management apparatus is operational, preventing key loss during maintenance periods.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The key management apparatus acts as an intermediary between the key generation apparatus and the QKDN management apparatus. It temporarily holds cryptographic keys in its storage unit when the management apparatus is unavailable, facilitating smooth key registration once the management apparatus resumes operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If cryptographic keys are continuously generated by key generation apparatuses, then key availability for quantum cryptographic communication is improved, but keys may be lost if the QKDN management apparatus is not operational to register them

Engineering Contradiction:

ImproveKey generation efficiencyVSAvoidKey registration reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The key management apparatus performs preliminary storage of cryptographic keys before they can be registered with the QKDN management apparatus. This preliminary action ensures that continuously generated keys are not lost even when the management apparatus is temporarily non-operational.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The key management apparatus maintains continuous operation to store cryptographic keys generated by the key generation apparatuses, even when the QKDN management apparatus is stopped. This continuity ensures that key generation productivity is maintained while reliability is protected through local storage.

Inventive Principle:

Principle #20Continuity of useful action

3Productivity

If the QKDN management apparatus operates continuously, then key life cycle information can be registered without interruption, but system complexity and energy consumption increase

Engineering Contradiction:

ImproveKey management efficiencyVSAvoidEnergy consumption of management apparatus

Core Design Contradiction:

ProductivityVSUse of energy by stationary object

Solution Approach 1:

The key management apparatus performs preliminary storage of cryptographic keys and their associated life cycle information locally. This allows the QKDN management apparatus to be stopped periodically for energy conservation while keys remain safely stored and can be registered when the management apparatus is operational.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system allows the QKDN management apparatus to operate periodically rather than continuously. The key management apparatus stores keys during periods when the management apparatus is stopped, and performs batch registration when the management apparatus is operational, reducing overall energy consumption while maintaining key management efficiency.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS20250293866A1Quantum key distribution system, key management apparatus, and key management method

Publication Date: 2025.09.18 NEC CORP

AI summary

In a quantum key distribution system according to the present disclosure, each key management apparatus includes: a storage unit; a monitoring unit configured to monitor whether or not the QKDN management apparatus is in operation; and a registration control unit configured to, in a case where the monitoring unit determines that an operation of the QKDN management apparatus is stopped, store in the storage unit the cryptographic key before information indicating that the cryptographic key has been generated by the key generation apparatus managed by the key management apparatus is registered in the QKDN management apparatus as the life cycle information, and in a case where the monitoring unit determines that an operation of the QKDN management apparatus is started, register in the QKDN management apparatus the life cycle information about the cryptographic key stored in the storage unit.