Anonymous Quantum Conference Key Agreement

Frederik Hahn,Anna Pappa,Jarn De Jong

doi:10.1103/prxquantum.1.020325

Abstract

Conference Key Agreement (CKA) is a cryptographic effort of multiple parties to establish a shared secret key. In future quantum networks, generating secret keys in an anonymous way is of tremendous importance for parties that want to keep their shared key secret and at the same time protect their own identity. We provide a definition of anonymity for general protocols and present a CKA protocol that is provably anonymous under realistic adversarial scenarios. We base our protocol on shared Greenberger-Horne-Zeilinger states, which have been proposed as more efficient resources for CKA protocols, compared to bipartite entangled resources. The existence of secure and anonymous protocols based on multipartite entangled states provides a new insight on their potential as resources and paves the way for further applications.

Highlights

One of the main applications of quantum-information processing is to provide additional security for communication
We provide a definition of anonymity for general protocols and present a Conference key agreement (CKA) protocol that is provably anonymous under realistic adversarial scenarios
We base our protocol on shared Greenberger-HorneZeilinger states, which have been proposed as more efficient resources for CKA protocols, compared to bipartite entangled resources

Summary

INTRODUCTION

One of the main applications of quantum-information processing is to provide additional security for communication. The most common setting is one of two parties, Alice and Bob, who want to establish a shared secret key in order to encrypt further communication. We examine a more generalized scenario, where several parties want to establish a shared secret key In this multiparty setting we introduce a new notion of anonymity, where we request that the identities of the parties sharing the secret key are all protected. We achieve anonymous conference key agreement, which allows a sender to transmit a private message to specific receivers of her choice, while keeping their identities secret from external parties and even from each other. We either assume Eve to follow the protocol and control a single node in the network, or to diverge from the protocol and control multiple nonparticipating nodes

PRELIMINARIES

GENERATING ANONYMOUS MULTIPARTY ENTANGLEMENT

ANONYMOUS QUANTUM CONFERENCE KEY AGREEMENT

DISCUSSION

Anonymity during the Verification rounds

Anonymity during the KeyGen rounds