Semi-quantum key distribution using qudit systems and security proof

Most prior semi-quantum key distribution (SQKD) protocols are designed in the context of qubits. In this paper, we proposed an SQKD protocol using (d+1) quantum states in two mutually unbiased bases in the context of qudits without invoking the classical party's measurement capability. It not only decreases the quantum states sent by quantum party by half, but also improves the efficiency of key rate than qubits do. To prove the security of present protocol, we first illustrate that the present protocol is completely robust, and then prove its unconditional security from information theoretical perspective by computing its key rate and noise tolerance against cloning-based individual attack. The unconditional security proof demonstrates that the higher dimension of quantum system is, the higher key rate can be obtained and the higher noise tolerance is allowed in depolarization channel.

Automated summary

This paper proposes a semi-quantum key distribution protocol using (d+1) quantum states, without requiring the classical party's measurement capability. It improves the key rate and noise tolerance against attacks.