Collective attack free controlled quantum key agreement without quantum memory

TL;DR

This paper introduces a new secure controlled quantum key agreement protocol that does not require quantum memory and uses easier-to-maintain quantum resources, improving efficiency and security over existing schemes.

Contribution

The paper presents a novel quantum key agreement protocol that is secure against impersonation and collective attacks, and does not require quantum memory, unlike previous protocols.

Findings

Protocol is secure against impersonation and collective attacks.

Does not require quantum memory, reducing resource complexity.

Uses easier-to-produce quantum states like Bell and single photons.

Abstract

Here we present a new protocol for controlled quantum key agreement and another protocol for key agreement with a specific focus on the security analysis. Specifically, detailed security proof is provided against impersonated fraudulent attack and collective attacks and it is established that the proposed protocols are not only secure, but they also satisfy other desired properties of such schemes (i.e., fairness and correctness). Further, the proposed schemes are critically compared with a set of schemes for quantum key agreement and an existing scheme for controlled quantum key agreement (Tang et al.'s protocol) in terms of efficiency and the required quantum resources. Especially, it is observed that in contrast to the existing schemes, the present scheme does not require quantum memory. In addition, the protocol for controlled quantum key agreement proposed here is found to require quantum resources (Bell state and single photon state) that are easier to produce and maintain compared to the quantum resources (GHZ states) required by the only known existing protocol for the same purpose, i.e., Tang et al.'s protocol.