Quantum Key Distribution Security Parameter Adjustment

Solution Overview

Problem

Conventional quantum key distribution systems face challenges in balancing security and key update rate, as the number of photons per pulse affects both security and transmission distance, making it difficult to meet user requests for varying levels of security and key update rates.

Innovation Solution

The system allows for varying the mean number of photons per optical pulse and the eavesdropping possibility parameter in privacy amplification processing, enabling users to set the degree of security and key update rate according to their requirements by adjusting the security parameter and eavesdropping proportion, thereby generating cryptographic keys with specific security and length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the mean number of photons per pulse is increased to improve transmission distance and key update rate, then the security level decreases due to higher eavesdropping possibility

Engineering Contradiction:

Improvekey update rateVSAvoidsecurity level

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies dynamics by making the security parameter adjustable and variable. The system allows dynamic adjustment of the security parameter to balance between security level and key update rate based on user requirements. This enables the system to adapt its operation mode - using higher photon counts for faster key updates when security can be compromised, or lower photon counts for higher security when needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent directly applies parameter changes by introducing an adjustable security parameter that modifies the relationship between photon count and security. By changing this parameter, the system can optimize the trade-off between transmission distance (requiring more photons), key update rate (benefiting from more photons), and security level (requiring fewer photons). This parameter adjustment mechanism resolves the contradiction by allowing operational flexibility.

Inventive Principle:

Principle #35Parameter changes

2Length of stationary object

If the mean number of photons per pulse is increased to extend transmission distance, then the security level decreases due to higher eavesdropping possibility

Engineering Contradiction:

Improvetransmission distanceVSAvoidsecurity level

Core Design Contradiction:

Length of stationary objectVSReliability

Solution Approach 1:

The patent applies dynamics by making the security parameter adjustable and variable. The system allows dynamic adjustment of the security parameter to balance between security level and key update rate based on user requirements. This enables the system to adapt its operation mode - using higher photon counts for faster key updates when security can be compromised, or lower photon counts for higher security when needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent directly applies parameter changes by introducing an adjustable security parameter that modifies the relationship between photon count and security. By changing this parameter, the system can optimize the trade-off between transmission distance (requiring more photons), key update rate (benefiting from more photons), and security level (requiring fewer photons). This parameter adjustment mechanism resolves the contradiction by allowing operational flexibility.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If conventional quantum key distribution is used with fixed security parameters, then the system cannot meet user requests for varying security levels and key update rates

Engineering Contradiction:

Improvecustomizable security levelsVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing a security parameter that serves multiple functions simultaneously. This single parameter controls both the security level and the key update rate, allowing the system to meet various user requirements without adding complex separate control mechanisms. The parameter acts as a universal control that coordinates multiple system behaviors, achieving adaptability without proportional increases in complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9160529B2Secret communication system and method for generating shared secret information

Publication Date: 2015.10.13 NEC CORP

AI summary

A user request can be reflected in the degree of security of an updated key in quantum key distribution. A sender and a receiver are connected through optical fiber. A quantum transmitter in the sender and a quantum receiver in the receiver carry out basis reconciliation and error correction through a quantum channel, based on a source of a key sent from the quantum transmitter and on a raw key received by the quantum receiver. Under the control of security control sections in the sender and receiver, the amount of information having the possibility of being intercepted, which is determined in accordance with a degree of security requested by a user, is removed from the key information after error correction, whereby a final cryptographic key is generated. Secret communication is performed between encryption/decryption sections in the sender and receiver by using the cryptographic key thus updated.