Conference Key Research Articles

Efficient source-independent quantum conference key agreement.

Quantum conference key agreement (QCKA) enables the unconditional secure distribution of conference keys among multiple participants. Due to challenges in high-fidelity preparation and long-distance distribution of multi-photon entanglement, entanglement-based QCKA is facing severe limitations in both key rate and scalability. Here, we propose a source-independent QCKA scheme utilizing the post-matching method, feasible within the entangled photon pair distribution network. We introduce an equivalent distributing virtual multi-photon entanglement protocol for providing unconditional security proof even in the case of coherent attacks. For the symmetry star network, compared with the previous n-photon entanglement protocol, the conference key rate is improved from O(ηn) to O(η2), where η is the transmittance from the entanglement source to one participant. Simulation results show that the performance of our protocol has multiple orders of magnitude advantages in the intercity distance. We anticipate that our approach will demonstrate its potential in the implementation of quantum networks.

Overcoming Fundamental Bounds on Quantum Conference Key Agreement

Twin-Field Quantum Key Distribution (TF-QKD) enables two distant parties to establish a shared secret key, by interfering weak coherent pulses (WCPs) in an intermediate measuring station. This allows TF-QKD to reach greater distances than traditional QKD schemes and makes it the only scheme capable of beating the repeaterless bound on the bipartite private capacity. Here, we generalize TF-QKD to the multipartite scenario. Specifically, we propose a practical conference key agreement (CKA) protocol that only uses WCPs and linear optics and prove its security with a multiparty decoy-state method. Our protocol allows an arbitrary number of parties to establish a secret conference key by single-photon interference, enabling it to overcome recent bounds on the rate at which conference keys can be established in quantum networks without a repeater.

Multipartite Intrinsic Non-Locality and Device-Independent Conference Key Agreement

In this work, we introduce multipartite intrinsic non-locality as a method for quantifying resources in the multipartite scenario of device-independent (DI) conference key agreement. We prove that multipartite intrinsic non-locality is additive, convex, and monotone under a class of free operations called local operations and common randomness. As one of our technical contributions, we establish a chain rule for two variants of multipartite mutual information, which we then use to prove that multipartite intrinsic non-locality is additive. This chain rule may be of independent interest in other contexts. All of these properties of multipartite intrinsic non-locality are helpful in establishing the main result of our paper: multipartite intrinsic non-locality is an upper bound on secret key rate in the general multipartite scenario of DI conference key agreement. We discuss various examples of DI conference key protocols and compare our upper bounds for these protocols with known lower bounds. Finally, we calculate upper bounds on recent experimental realizations of DI quantum key distribution.

Finite-key analysis for quantum conference key agreement with asymmetric channels

As an essential ingredient of quantum networks, quantum conference key agreement (QCKA) provides unconditional secret keys among multiple parties, which enables only legitimate users to decrypt the encrypted message. Recently, some QCKA protocols employing twin-field was proposed to promote transmission distance. These protocols, however, suffer from relatively low conference key rate and short transmission distance over asymmetric channels, which demands a prompt solution in practice. Here, we consider a tripartite QCKA protocol utilizing the idea of sending-or-not-sending twin-field scheme and propose a high-efficiency QCKA over asymmetric channels by removing the symmetry parameters condition. Besides, we provide a composable finite-key analysis with rigorous security proof against general attacks by exploiting the entropic uncertainty relation for multiparty system. Our protocol greatly improves the feasibility to establish conference keys over asymmetric channels.

Genuine multipartite entanglement is not a precondition for secure conference key agreement

The authors show that in a Conference Key Agreement protocol the resource state used at each round of the protocol is not required to be Genuine Multipartite Entangled in order to establish a secret conference key.

High Key Rate Quantum Conference Key Agreement With Unconditional Security

Quantum cryptography is a major ingredient of the future quantum internet that promises various secure communication tasks. Quantum conference key agreement (CKA) is an important cryptographic primitive of quantum cryptography, which provides the conference key among multiple users simultaneously. However, quantum CKA is currently far from practical application due to the low conference key rate. Here, we propose a quantum CKA protocol of three users with information-theoretic security. Our protocol only requires phase-randomized weak coherent sources and threshold single-photon detectors, and is anticipated to be experimentally demonstrated over 600 km under current technology. Our scheme can be widely implemented in the approaching large-scale quantum network.

Anonymous Quantum Conference Key Agreement

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.

Quantum Conference Key Agreement: A Review

AbstractConference key agreement (CKA), or multipartite key distribution, is a cryptographic task where more than two parties wish to establish a common secret key. A composition of bipartite quantum key distribution protocols can accomplish this task. However, the existence of multipartite quantum correlations allows for new and potentially more efficient protocols, to be applied in future quantum networks. Here, the existing quantum CKA protocols based on multipartite entanglement are reviewed, both in the device‐dependent and the device‐independent scenario.

On the conference key distribution system with user anonymity

Conference Key Distribution Systems (CKDS) are well-analyzed systems for the computation and distribution of a symmetric key shared amongst a session's participants. We focus on previous CKDS with user anonymity and we propose modifications from the perspective of anonymity, dynamicity, efficiency and security crystallized in a novel CKDS design. The security of the proposed anonymous CKDS is based on the difficulty of computing discrete logarithms over Elliptic Curves, the intractability of inverting one-way hash functions and the creation of random, however disjoint, pseudonyms by the group members. Under these modifications, our proposed dynamic CKDS can be ported to clustered Mobile Ad Hoc Networks so that the members of a mobile group can rapidly establish a shared Conference Key. We demonstrate the effectiveness of the proposed scheme through performance comparisons and security analysis that covers passive and active attack scenarios.

Resource state structure for controlled quantum key distribution

Quantum entanglement plays a pivotal role in many communication protocols, like secret sharing and quantum cryptography. We consider a scenario where more than two parties are involved in a protocol and share a multipartite entangled state. In particular, we considered the protocol of Controlled Quantum Key Distribution (CoQKD), introduced in the Ref. Chin. Phys. Lett. 20, 183-185 (2003), where, two parties, Alice and Bob establish a key with the cooperation of other parties. Other parties control/supervise whether Alice and Bob can establish the key, its security and key rate. We discuss the case of three parties in detail and find suitable resource states. We discuss the controlling power of the third party, Charlie. We also examine the usefulness of the new resource states for generating conference key and for cooperative teleportation. We find that recently introduced Bell inequalities can be useful to establish the security of the conference key. We also generalize the scenario to more than three parties.

Tripartite Layered Quantum Key Distribution Scheme with a Symmetrical Key Structure

Asymmetric entanglement could provide a crucial layered key structure for quantum cryptography. A new symmetrical tripartite quantum key distribution scheme based on the simplest layered quantum key distribution (L-QKD) model is devised. With an interesting rotational symmetrical key distribution scheme, the proposed tripartite QKD protocol could establish a more integrated key system, which expands the number of conference keys for secure broadcast and distribute layered secret keys among any legitimate participants simultaneously. The proposed scheme is more flexible, robust and efficient to guarantee the fairness among communication parties than the original L-QKD protocol, and our scheme also could be applied to encryption in the butterfly network precisely. Moreover, based on three asymmetric (4, 4, 2) entangled state, a novel symmetric (4, 4, 4) entangled state to implement L-QKD scheme is discussed. Finally, the security of L-QKD scheme is analyzed via information-theoretic proof.

Anonymous and Traceable Group Data Sharing in Cloud Computing

Group data sharing in cloud environments has become a hot topic in recent decades. With the popularity of cloud computing, how to achieve secure and efficient data sharing in cloud environments is an urgent problem to be solved. In addition, how to achieve both anonymity and traceability is also a challenge in the cloud for data sharing. This paper focuses on enabling data sharing and storage for the same group in the cloud with high security and efficiency in an anonymous manner. By leveraging the key agreement and the group signature, a novel traceable group data sharing scheme is proposed to support anonymous multiple users in public clouds. On the one hand, group members can communicate anonymously with respect to the group signature, and the real identities of members can be traced if necessary. On the other hand, a common conference key is derived based on the key agreement to enable group members to share and store their data securely. Note that a symmetric balanced incomplete block design is utilized for key generation, which substantially reduces the burden on members to derive a common conference key. Both theoretical and experimental analyses demonstrate that the proposed scheme is secure and efficient for group data sharing in cloud computing.

Improving Access and Systems of Care for Evidence-based Childhood Obesity Treatment: Conference Key Findings and Next Steps

Improving Access and Systems of Care for Evidence-based Childhood Obesity Treatment: Conference Key Findings and Next Steps

Efficient security zones implementation through hierarchical group key management at NoC-based MPSoCs

Sensitive applications are split into the IP cores of the Multi-Processors System-on-Chip (MPSoCs). In order to isolate the sensitive communication among such IP cores, security zones based on conference keys agreement can be built. However, the flexibility and dynamic nature of MPSoCs force reshaping the security zones at runtime. It is still a challenge to achieve efficient computation and distribution of new conference keys in MPSoC environments. In order to solve this problem, in this work we propose the combination of two techniques: i) high performance NoC, able to efficiently communicate data and control packets in the system; and ii) hierarchical group-key management for efficient security zone modification. We implement three hierarchical protocols and we show that by decentralizing the security management of the rekeying process and using a two-level NoC, it is possible to achieve an improvement of the performance compared to the previous flat approaches.

Challenges of Geography in Education. Proposals from the EUROGEO Conference (Amsterdam, The Netherlands, 2-3 March 2017)

From March 2nd to 3rd, 2017, the EUROGEO (European Association of Geographers) Conference 2017 took place in Amsterdam. It was an occasion for geography teachers and professors to attend plenary lectures, paper and poster sessions and workshops focused on Geography in Education. The title of the Conference Key Challenges for Geographical Education indicates the underlying theme centred on the relationships between geography teaching, global understanding and the future of the worldwide society. Satellite Seminars were dedicated to the Geocapabilities project.

Conference key establishment protocol using a multivariate polynomial and its applications

AbstractIn 1992, a non‐interactive k‐secure m‐conference protocol based on an m‐variate polynomial has been proposed. Each user needs to store a (m − 1)‐polynomial having degree k as a private share. A secret conference key involving m users can be computed by each conference member non‐interactively using each private share. There is no overhead to exchange information in order to establish a conference key. However, the storage space of each user is exponentially proportional to the group size of the conference. In this paper, we propose a key establishment protocol using a multivariate polynomial in ZN, where N is a RSA modulus. One unique feature of using this special type of polynomials for conference key protocol is that the storage space of each user is fixed and is independent to the group size of the conference. User can use their shares obtained from a key generation center initially to establish conference keys consisting of different users. Furthermore, we propose two applications to demonstrate the importance of using this special type of polynomials to design solutions. One is the private reconstruction of secret in a secret sharing scheme over network, and the other is the secure group communication. Copyright © 2014 John Wiley & Sons, Ltd.

Identity-based key agreement protocol employing a symmetric balanced incomplete block design

Key agreement protocol is a fundamental protocol in cryptography whereby two or more participants can agree on a common conference key in order to communicate securely among themselves. In this situation, the participants can securely send and receive messages with each other. An adversary not having access to the conference key will not be able to decrypt the messages. In this paper, we propose a novel identity-based authenticated multi user key agreement protocol employing a symmetric balanced incomplete block design. Our protocol is built on elliptic curve cryptography and takes advantage of a kind of bilinear map called Weil pairing. The protocol presented can provide an identification (ID)-based authentication service and resist different key attacks. Furthermore, our protocol is efficient and needs only two rounds for generating a common conference key. It is worth noting that the com munication cost for generating a conference key in our protocol is only O(n√n) and the computation cost is only O(nm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), where n implies the number of participants and m denotes the extension degree of the finite field Fp <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sup> . In addition, in order to resist the different key attack from malicious participants, our protocol can be further extended to provide the fault tolerant property.

UNCONDITIONALLY SECURE CONFERENCE KEY DISTRIBUTION: SECURITY NOTIONS, BOUNDS AND CONSTRUCTIONS

A conference key distribution is a protocol that allows designated subset of users to calculate a shared private key. We consider unconditionally secure conference key distribution systems where the adversary has unlimited computational power, and focuses on a stronger and more realistic adversary model, proposed by Safavi-Naini and Jiang, in which the adversary in addition to corrupting subsets of users and obtaining their private keys, can access the conference keys of a number of uncorrupted conferences. We consider alternative definitions of security with this adversary model and show the relationship between them. An important efficiency parameter for conference key distribution systems is the size of the users' private keys. We derive lower bounds on the size of this key and discuss the results in comparison with the known bounds. We also consider one-round Interactive Conference Key Distribution Systems (ICKDS) in the new adversarial model where the adversary in addition to learning the private keys of the corrupted users and a number of conference keys, has access to the transcripts of some conferences. We show that under this new adversary model, the previously proposed one round protocol of Blundo et. al. is no longer secure and we construct an ICKDS with provable security in the new adversarial model.

An Effective Contributory Re-Keying Approach to Compute Conference Key

Problem statement: With the explosive growth of and internet and web applications many emerging group-oriented distributed applications such as tele/video-conferencing, multiplayer games are based on group communication model that need security services such as privacy and data integrity Hence a secure distributed group key agreement is required to establish and authenticate a common group key for secure and private communication. There is a need for security services to provide group-oriented communication privacy and data integrity. It is important that members of the group can establish a common secret key for encrypting group communication. A key tree approach has been proposed by many authors to distribute group key in such a way that the rekeying cost scales with the logarithm of the group size for a join or leave request. The efficiency of this key tree approach critically depends on whether the key tree remains balanced over time as members join or leaves Approach: Instead of performing individual re-keying operations, an interval-based approach of re keying is adopted in the proposed scheme. Results: In the proposed scheme Queue-merge algorithm is used for rekeying which substantially reduces the computation cost and communication cost. The comparison shows that queue merge algorithm performs better than Batch algorithm in terms of minimizing the key tree and presumes better node density thereby reducing the computation cost. Conclusion: Performance comparison also shows reduced number of renewed nodes for various rekeying interval which reduces the communication cost.

Efficient Distribution of Conference Key for Dynamic Groups

Efficient Distribution of Conference Key for Dynamic Groups