Secure Key Relay Using Blinding Value Segmentation
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Solution Overview
Problem
Existing quantum key distribution (QKD) networks require multiple trusted nodes for key relay, which introduces potential security risks and increases technical complexity due to the need for physical protection of these nodes.
Innovation Solution
A method and system for secure key relay that uses secret sharing protocols, specifically the Shamir secret sharing protocol, to distribute and reconstruct blinding values, allowing intermediate relay nodes to be untrusted, reducing the reliance on physical protection and enhancing security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If trusted nodes are used for key relay in QKD networks, then key distribution can be achieved over long distances, but security risks increase and physical protection measures are required
Solution Approach 1:
The patent segments the blinding value into multiple shares and distributes them to different intermediate relay nodes. Each node only holds a portion of the blinding value, making it impossible for any single compromised node to access the complete encryption key. This segmentation resolves the contradiction by enabling long-distance key relay through multiple nodes while maintaining security, as the segmented blinding values cannot be reconstructed unless all shares are collected.
Solution Approach 2:
The patent introduces untrusted intermediate relay nodes as mediators that forward encrypted quantum keys without having access to the decryption capability. These intermediary nodes operate without requiring physical protection because they cannot access the plaintext key material, thus enabling extended transmission distance while eliminating the security vulnerability associated with traditional trusted nodes.
2Reliability
If trusted nodes with physical protection are used for key relay, then security can be maintained, but device complexity and cost increase
Solution Approach 1:
The blinding value is divided into multiple shares distributed across different relay nodes, so that no single node possesses the complete decryption capability. This segmentation eliminates the need for physical protection measures at intermediate nodes, reducing device complexity and cost while maintaining security through cryptographic rather than physical means.
Solution Approach 2:
The patent replaces expensive, physically protected trusted nodes with simpler, untrusted relay nodes that require no special security measures. These intermediate nodes can be standard, off-the-shelf equipment without specialized security hardware, significantly reducing the complexity and cost of the key relay infrastructure.
3Length of stationary object
If multiple trusted nodes are deployed for key relay, then long-distance quantum key distribution is enabled, but the impact of security breaches increases
Solution Approach 1:
By segmenting the blinding value into shares held by different relay nodes, the patent ensures that a security breach at any single node only exposes a fraction of the blinding value, which is insufficient to reconstruct the encryption key. This dramatically reduces the impact of security breaches while enabling long-distance key distribution through multiple relay nodes.
Solution Approach 2:
The patent converts the potential harm of having multiple relay nodes (increased attack surface) into a benefit by using untrusted nodes with segmented credentials. The very presence of multiple nodes, which previously increased security risk, now provides redundancy and security through the segmentation mechanism - the system becomes more secure despite having multiple relay points.
Data Source
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AI summary
A method and system for performing a secure key relay of an encryption key, Kenc, provided by an initial node, KN0, and used by an encoding unit (ENC) of a first data transceiver for encoding plain data, Pdata, to provide encrypted cipher data, Cdata, transported via a data transport link, DTL, to a decoding unit (DEC) of a second data transceiver which decodes the transported cipher data, Cdata, using the relayed encryption key, Kenc, provided by a terminal node, KNN, as a decoding key to retrieve the plain data, Pdata, wherein the relay of the encryption key, Kenc, from the initial node, KN0, to the terminal node, KNN, is performed by means of intermediate relay nodes, KN1,KN2...KNN-1, and comprises the steps of sharing (S1) QKD-keys, K, between the nodes via secure quantum channels, QCH, of a quantum key distribution network, QKDN; performing (S2) encryption of shared QKD-KEYS, K, at the initial node, KN0, and at each intermediate relay node, KN1, KN2...KNN-1, and blinding them with a blinding value, Si, of the respective node to provide an encrypted cipher key, CKi, by the initial node, KN0, and by each intermediate relay node, KN1, KN2...KNN-1; distributing (S3) or pre-distributing the blinding values, Si, of the initial node, KN0, and of each intermediate relay node, KN1,KN2...KNN-1,; transmitting (S4) the encrypted cipher keys, CKi, of the initial node, KN0, and of each of the intermediate relay nodes, KN1,KN2...KNN-1, to the terminal node, KNN;; performing (S6) by the terminal node, KNN, logic operations on reconstructed or pre-distributed blinding values, Si, on the basis of the encrypted cipher keys, CKi, received by the terminal node, KNN, from the initial node, KN0, and received from each of the intermediate relay nodes, KN1,KN2...KNN-1, to provide the encryption key, Kenc, used by the decoding unit (DEC) of the second data transceiver as a decoding key to retrieve the plain data, Pdata.