Secure sharing of one-sided quantum randomness using entangled coherent states

In quantum key distribution, secret randomness is extracted quantum-mechanically from two-sided local random choices of measurement bases. Subsequently, the public announcement of basis information is necessary to perform a security check and establish the key. Recent studies have demonstrated that, provided the basis information is accessible, even adversaries with limited computational power can readily compromise the key through side-channel attacks. In this paper, we propose a quantum key distribution scheme using entangled coherent states. The present scheme is based on the secure exchange of one-sided quantum randomness, thus obviating the necessity for basis-information announcement. This effectively closes the security loophole associated with access to basis information during side-channel attacks. The security of the present protocol has been verified against both local and global quantum attacks. Furthermore, the impact of high photon loss and an authentication scheme has been discussed.