Yuen's Criticisms on Security of Quantum Key Distribution and Onward

摘要

Quantum Key Distribution (QKD) has been attracting researchers that it wouldprovide provable security to distribute secret keys since its birth in 1984.Since 2005, the trace distance between an ideal quantum state and an actuallydistributed state has been employed to evaluate its security level, and thetrace distance was given an interpretation that it would be a maximum failureprobability in distributing perfectly secure keys. However, in 2009, H. P. Yuencriticized that the trace distance would not have such an interpretation. Sincethen, O. Hirota, K. Kato, and T. Iwakoshi have been warning to make people payattention to Yuen's criticisms. In 2015, T. Iwakoshi precisely explained whyYuen has been correct. In 2016, Yuen himself published a paper to explain thepotentially unsolved problems in QKD. This study precisely explains the mostimportant problems given in Yuen's paper, and gives recent topics around QKDand other quantum cryptographic protocols.