An improved QKD protocol without public announcement basis using periodically derived basis

Abstract

The quantum key distribution (QKD) protocol provides an absolutely secure way to distribute secret keys, where security can be guaranteed by quantum mechanics. To raise the key generation rate of classical BB84 QKD protocol, Hwang et al. (Phys Lett A 244(6):489–494, 1998) proposed a subtle variation (Hwang protocol), in which a pre-shared secret string is used to generate the consistent basis. Although the security of Hwang protocol has been verified in ideal condition, its practicality is still being studied in more depth. In this work, we propose a simple attack strategy to obtain all preparation basis by stealing partial information in each round. To eliminate this security threat, we further propose an improved QKD protocol using the idea of iteratively updating the basis. Furthermore, we apply our improved method to decoy-state QKD protocol and double its key generation rate.