QKD Trusted Node Key Agreement for Long-Distance Security
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Solution Overview
Problem
Quantum Key Distribution (QKD) systems have a limited distance optical pulse transmission capability, typically up to 200 km, and are expensive, making them impractical for widespread use, especially for communicating parties farther apart, and existing solutions like trusted nodes do not significantly extend the distance and require establishing two separate quantum keys.
Innovation Solution
A method involving multiple nodes where non-orthogonal quantum states are prepared or measured using different sets of basis states, with a key agreement stage between nodes to generate a shared secret key, allowing for longer distance secure communication using either prepare-and-measure or entanglement protocols, and employing encryption techniques like AES512 for secure data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If QKD systems are used for secure communication, then security is improved, but transmission distance is limited to about 200 km
Solution Approach 1:
The patent introduces a trusted node as an intermediary between distant communicating parties. This trusted node contains both a transmitter (Alice) and a receiver (Bob) and establishes separate quantum keys with each party, enabling secure communication over distances exceeding 200 km by bridging the gap between distant nodes that cannot directly establish quantum keys
Solution Approach 2:
The patent divides the long-distance communication path into multiple segments, each under 200 km, by introducing intermediate trusted nodes. Each segment establishes its own quantum key independently, allowing the overall system to achieve long-distance secure communication by combining multiple shorter secure links
2Length of moving object
If trusted nodes are used to extend distance, then transmission distance is increased, but device complexity increases due to requiring two separate quantum keys
Solution Approach 1:
The patent merges the functionality of multiple quantum key establishment processes into a unified protocol. The trusted node combines its separate quantum keys with the end nodes through cryptographic operations to generate a single shared secret key, eliminating the need for multiple separate key management systems and reducing overall system complexity
3Adaptability or versatility
If QKD systems are deployed widely, then security coverage is improved, but cost increases making them impractical for many companies
Solution Approach 1:
The patent creates a universal QKD architecture where trusted nodes can serve multiple purposes: extending distance for different user pairs, providing secure key distribution for various applications, and enabling both direct and indirect communication modes. This multi-functionality increases adaptability while avoiding the need for separate dedicated systems for each use case, thereby reducing overall deployment cost
Data Source
AI summary
There is herein disclosed a method of performing Quantum Key Distribution for generating a shared secret key, the method including, at a first node, preparing or measuring a plurality of non-orthogonal quantum states, each of the plurality of non-orthogonal quantum states being prepared or measured using a respective one of a first set of basis states, and, at a second node, preparing or measuring the plurality of non-orthogonal quantum states each, of the plurality of non-orthogonal quantum states being prepared or measured using a respective one of a second set of basis states, and, at a third node, obtaining an indication of the first set of basis states from the first node and performing a key agreement stage with a fourth node to agree the shared secret key, the key agreement stage involving the first and second sets of basis states.