Analysis of Quantum Key Randomness Based on Cold Region Practical QKD System

Analysis of Quantum Key Randomness Based on Cold Region Practical QKD System

Quantum key distribution (QKD) systems have extremely strict requirements for random numbers. Random selection of basis vector is required when modulating the quantum state. The quality of randomness directly determines the security of final keys. The randomness of pseudorandom numbers based on mathematical algorithms depends on input seeds. As pseudorandom numbers may be cracked when used frequently, they cannot meet requirements of QKD protocols for random numbers. The output of the quantum random number generator is basis on the quantum mechanics intrinsic randomness, and is generally considered to have true randomness. In order to verify the randomness of quantum key generated by the cold region practical QKD system, BB84 protocol-based without post-processing, polarization-coded postprocessing, phase-coded post-processing QKD systems were constructed, which generated three types of quantum keys as data sources to be analyzed. Meanwhile, pseudorandom keys generated by chaos algorithms and physical random keys generated by atmospheric noises were introduced for comparison. The experiment adopted national institute of standards and technology (NIST) to implement routine verification on stochastic performances of five keys. Additionally, we proposed a novel visualized randomness verification method based on statistical feature parameters. The results indicated that the quantum key generated by QKD systems with post-processing had superior stochastic performance.