Unlike traditional communication, quantum key distribution (QKD) can reach unconditional security and thus attracts intensive studies. Among all existing QKD protocols, round-robin-differential-phase-shift (RRDPS) protocol can be running without monitoring signal disturbance, which significantly simplifies its flow and improves its tolerance of error rate. Although several security proofs of RRDPS have been given, a tight finite-key analysis with a practical phase-randomized source is still missing. In this paper, we propose an improved security proof of RRDPS against the most general coherent attack based on the entropic uncertainty relation. What’s more, with the help of Azuma’s inequality, our proof can tackle finite-key effects primely. The proposed finite-key analysis keeps the advantages of phase randomization source and indicates experimentally acceptable numbers of pulses are sufficient to approach the asymptotical bound closely. The results shed light on practical QKD without monitoring signal disturbance.

与传统通信不同，量子密钥分发（QKD）可以达到无条件安全，因此吸引了大量研究。在所有现有的 QKD 协议中，循环差分相移 (RRDPS) 协议可以在不受监控信号干扰的情况下运行，这大大简化了其流程并提高了其对错误率的容忍度。尽管已经给出了 RRDPS 的几个安全证明，但仍然缺少具有实际相位随机源的严格有限密钥分析。在本文中，我们提出了一种基于熵不确定关系的改进的 RRDPS 安全证明，以对抗最普遍的相干攻击。更重要的是，在 Azuma 不等式的帮助下，我们的证明可以很好地解决有限键效应。所提出的有限密钥分析保留了相位随机源的优点，并表明实验上可接受的脉冲数足以接近渐近界。结果阐明了无需监测信号干扰的实用 QKD。