Intermediate Network Node Quantum Key Transmission via PQC XOR
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Solution Overview
Problem
Current quantum key distribution (QKD) systems are limited by the range of quantum key exchange, typically restricted to direct connections via radio links or fiber optic lines, with fiber optic connections limited to a few kilometers due to photon attenuation, necessitating the use of intermediate trusted nodes for key transmission, which requires complex security measures and high costs.
Innovation Solution
A method and intermediate network node design that uses Post Quantum Cryptography (PQC) to encrypt and decrypt quantum-secure keys via classic channels, ensuring the key remains outside the intermediate node, using bitwise XOR operations with PQC keys negotiated between input and output units, thereby maintaining security without the need for trusted nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If intermediate trusted nodes are used to transmit quantum keys over long distances via fiber optic lines, then the transmission range is extended beyond direct QKD limits, but the security requirements and operational complexity increase significantly
Solution Approach 1:
The patent introduces a quantum repeater as an intermediary device that enables long-distance quantum key distribution without requiring the key to be stored or processed in trusted nodes. The quantum repeater performs quantum memory storage, entanglement swapping, and purification operations to extend the transmission range while maintaining security, as the key never exists in classical form within the intermediate device.
Solution Approach 2:
The patent replaces the classical trusted node architecture with a quantum mechanical system based on entanglement and quantum teleportation. Instead of relying on classical encryption and physical security measures for intermediate nodes, the system uses quantum mechanical principles where the key remains in quantum form throughout the transmission chain, eliminating the need for complex physical security infrastructure.
2Length of stationary object
If intermediate nodes store and forward quantum keys, then key transmission over long distances is enabled, but the keys become accessible to node operators and require high-security trusted zones
Solution Approach 1:
The quantum repeater acts as a mediator that enables key transmission without the key being stored in intermediate nodes. The device performs quantum operations on flying qubits in transit, using quantum memory temporarily to store quantum states during entanglement swapping operations, but never converts them to classical form for storage or processing, thus maintaining security while enabling long-distance transmission.
Solution Approach 2:
The patent changes the fundamental parameter of key representation from classical bits to quantum states throughout the entire transmission chain. By maintaining the key in quantum form (superposition states) rather than converting to classical bits at intermediate nodes, the system eliminates the security vulnerability of key accessibility while enabling extended transmission range through quantum repeater operations.
3Reliability
If direct QKD connections are used between network nodes, then key security is maintained, but the transmission distance is limited to a few kilometers due to photon attenuation
Solution Approach 1:
The patent divides the long-distance quantum channel into multiple segments, each handled by a quantum repeater station. Instead of attempting direct transmission over long distances which suffers from exponential photon loss, the system segments the channel and uses entanglement swapping at intermediate repeater locations to extend the effective range while maintaining the security properties of direct QKD in each segment.
Solution Approach 2:
The quantum repeater performs preliminary entanglement generation and storage operations in advance, creating entangled pairs and storing them in quantum memory before they are needed for key distribution. This preliminary action allows the system to overcome photon attenuation by having pre-prepared quantum resources available when needed, extending the transmission range without compromising security.
Data Source
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AI summary
The invention relates to a solution for transmitting a quantum-safe key (user key) between two network nodes equipped with means for generating quantum-safe keys, but not directly connected to each other via a quantum channel. Here, the quantum-safe user key, which serves for secure data transmission between the two network nodes, is generated in one of these network nodes and transmitted to the other via a transmission path with at least one intermediate network node (1) configured according to the invention.Within the network node (1), a bit sequence containing the user key, received at an input unit (2), is transmitted to an output unit (3) of the network node (1), which in turn sends the user key with a bit sequence, in the form of a bit sequence formed by bitwise XOR operation of the user key with a PQC key negotiated between the input unit (2) and the output unit (3) according to a PQC procedure. The user key is thus present in the network node (1) outside the units (2, 3) only in the form of the bit sequence formed by bitwise XOR operation with the PQC key.