Semi-quantum Key Distribution and Quantum Key Agreement

Abstract

The present researches in the quantum cryptography have covered wide range of research topics Particularly the topic of quantum key distribution (QKD) is the most attractive one Compare with the classical key distribution the security of the QKD protocol is based on the quantum physics which possesses the properties of the measurement uncertainty and no-cloning theorem However most of the QKD schemes assume that both participants equip the advanced quantum devices In this condition consider that the quantum computer is still in development stage and it’s hard to afford this assumption may become a restriction for a user to execute those QKD schemes without these devices Under this situation the “semi-quantum” environment was proposed to achieve the quantum communication with limited quantum capability In the case of semi-quantum key distribution (SQKD) however all the existing SQKD protocols utilize authenticated classical channels between the participants (i e the integrity and the originality of messages transmitted via the authenticated classical channel can be ensured) Without the use of the authenticated classical channels these SQKD protocols are vulnerable to man-in-the-middle attacks Besides in a QKD protocol the shared secret key is determined by a party or a key distribution center and subsequently distributed to the other participants However the participants in a communication may be dishonest and further threaten the generation of the shared key In that case the quantum key agreement (QKA) protocols can be applied The QKA protocols allow all the participants to negotiate the shared secret key which cannot be determined alone by any one or subset of the participants This thesis discloses a novel key manipulation problem which makes the existing QKA protocols vulnerable and unfair Based on above discussion this thesis first proposes authenticated SQKD (ASQKD) protocols which utilize public channels and pre-shared keys to authenticate users instead of using the authenticated classical channels In addition this thesis also proposes a multi-party SQKD protocol using N-particle GHZ-like states which allows numerous participants to establish a shared secret key Second based on that this thesis also gives a solution model Moreover a two-party QKA protocol and two multi-party QKA protocols with mediators based on the solution model are presented

Date of Award	2014 Sept 1
Original language	English
Supervisor	Tzone-Lih Hwang (Supervisor)