Quantum Key Distribution System with Segmented Entropy Generation
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Solution Overview
Problem
QKD systems require a high rate of entropy generation, which is challenging to achieve with existing random number generators, leading to bulky and costly solutions or reduced security due to the need for multiple generators.
Innovation Solution
The system employs a fully entropic QRNG for generating full entropy bit values, while using QRNGs with randomness expansion for generating basis and intensity values, significantly reducing the overall entropy rate by almost a factor of four.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high rate of entropy generation is used to meet QKD security requirements, then security is improved, but the system becomes bulky and costly due to requiring multiple high-rate random number generators
Solution Approach 1:
The patent segments the random bit generation requirements into two distinct functions: a first random bit generator dedicated to generating basis information with high entropy rate, and a second random bit generator for generating message information with lower entropy rate. This segmentation allows each generator to be optimized for its specific purpose, reducing the need for multiple high-rate generators while maintaining security.
Solution Approach 2:
The patent inverts the conventional approach by assigning the higher entropy rate requirement to the basis information generation rather than the message information generation. Conventionally, the secret message would require the highest entropy, but the patent demonstrates that basis information actually requires the highest entropy rate for security, while message information can be generated with lower entropy rate through the established basis.
2Reliability
If multiple high-rate random number generators are used to ensure security, then security is improved, but the cost and size of the system increase
Solution Approach 1:
The patent divides the random bit generation task into two separate generators with different entropy rate requirements. The first generator produces basis information at high entropy rate, while the second generator produces message information at lower entropy rate. This segmentation reduces the total number of high-rate generators needed from multiple to just one, thereby reducing system cost and size while maintaining security.
3Device complexity
If a single random number generator is used to reduce system complexity, then device complexity is reduced, but the entropy generation rate becomes insufficient for secure QKD
Solution Approach 1:
The patent segments the entropy generation requirements into two levels: a first random bit generator providing high entropy rate for basis information, and a second random bit generator providing lower entropy rate for message information. This segmentation allows the system to achieve the necessary total entropy generation rate while using generators with different performance characteristics, thus balancing complexity and productivity.
Solution Approach 2:
The patent changes the entropy rate parameter of the random bit generators based on the specific information being generated. The first generator operates at high entropy rate for basis information, while the second operates at lower entropy rate for message information. This parameter adaptation allows the system to meet security requirements without unnecessarily high entropy generation rates throughout, optimizing the balance between complexity and productivity.
Data Source
Figure 1
AI summary
The present invention relates to a Quantum Key Distribution System comprising an emitter and a receiver adapted to communicate, wherein the emitter comprises an optical pulse source adapted to generate an optical pulse to be sent to the receiver, and at least one random bit generator adapted to set a bit value, a basis value and an intensity value of said optical pulse, wherein said at least one random bit generator comprises a bit value source adapted to generate full entropy to set said bit value of said optical pulse, a basis value source and an intensity value source, characterized in that said basis value source and said intensity value source are adapted to process entropy with expanded randomness to set said basis and said intensity of said optical pulse.