Authenticated Semi-Quantum Key Distribution Protocol Based on W States.

Area of Science:

• Quantum Information Science
• Cryptography
• Quantum Communication

Background:

• Wen et al. proposed an authenticated semi-quantum key distribution (ASQKD) protocol in 2019.
• The protocol utilized W states and GHZ-like states for identity and message authentication without pre-shared keys.

Purpose of the Study:

• To identify critical flaws in Wen et al.'s ASQKD protocol, specifically concerning W state teleportation and adherence to semi-quantum principles.
• To propose a novel and improved authenticated semi-quantum key distribution protocol.

Main Methods:

• Analysis of the W state teleportation mechanism in Wen et al.'s protocol to identify design flaws.
• Development of a new ASQKD protocol adhering to the definition of semi-quantum systems.
• Comparison of the proposed protocol with Wen et al.'s protocol based on security, hardware requirements, and efficiency.

Main Results:

• Wen et al.'s W state teleportation is malfunctioning due to an inappropriate design where Bob recovers states without photon position information.
• Wen et al.'s protocol incorrectly requires quantum memory, violating the semi-quantum definition.
• The proposed ASQKD protocol operates in a legal semi-quantum environment, requires only W states, and avoids classical cryptography.

Conclusions:

• The proposed ASQKD protocol rectifies the identified flaws, offering a more robust and efficient solution.
• The new protocol demonstrates a 1.6 times higher qubit efficiency compared to Wen et al.'s design.
• This work contributes to the advancement of secure and efficient quantum key distribution methods.