Secure multiparty quantum key agreement against collusive attacks

Hussein Abulkasim,Atefeh Mashatan,Shohini Ghose

doi:10.1038/s41598-021-88837-w

Abstract

Quantum key agreement enables remote participants to fairly establish a secure shared key based on their private inputs. In the circular-type multiparty quantum key agreement mode, two or more malicious participants can collude together to steal private inputs of honest participants or to generate the final key alone. In this work, we focus on a powerful collusive attack strategy in which two or more malicious participants in particular positions, can learn sensitive information or generate the final key alone without revealing their malicious behaviour. Many of the current circular-type multiparty quantum key agreement protocols are not secure against this collusive attack strategy. As an example, we analyze the security of a recently proposed multiparty key agreement protocol to show the vulnerability of existing circular-type multiparty quantum key agreement protocols against this collusive attack. Moreover, we design a general secure multiparty key agreement model that would remove this vulnerability from such circular-type key agreement protocols and describe the necessary steps to implement this model. The proposed model is general and does not depend on the specific physical implementation of the quantum key agreement.

Highlights

Quantum key agreement enables remote participants to fairly establish a secure shared key based on their private inputs
Taking SCWZ’s protocol19 as an example, we show how to address the vulnerability of circle-type multiparty quantum key agreement (CT-MQKA) protocols to the collusive attack
We showed that most of the existing circular-type multiparty quantum key agreement protocols are insecure against a specific type of collusive attack

Summary

OPEN Secure multiparty quantum key agreement against collusive attacks

Quantum key agreement enables remote participants to fairly establish a secure shared key based on their private inputs. Step [2] The server generates additional n sequences of random single qubits (called Ci ), which are used as decoy states to check the existence of eavesdroppers. Pi generates a sequence of random single qubits (C pi ) as in Steps [1] and [2], which are used as decoy qubits to check the existence of eavesdroppers in the quantum channel between Pi and Pi+1 F) Pi+2 encodes her or his information and sends the new sequences to the participants This process continues until Pi receives the secure quantum message ( Si→i−1 ) from Pi−1 ; here, the symbol “−” in “i − 1” represents the subtraction mod n.

Illustration of the proposed protocol

Conclusion

Additional information