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Causal ordering of broadcasts is a widely used
requirement in collaborative distributed software systems. We
consider Byzantine-tolerant causal ordering of broadcasts in a
replicated data store implemented over an incomplete graph
network topology, wherein messages of the broadcast are sent
via flooding. We propose two protocols to achieve this. The
incomplete graph topology also occurs naturally in wireless
networks and in overlay peer-to-peer networks. We identify four
properties – safety, liveness, no impersonation, and no avatars
– that a Byzantine-tolerant causal broadcast algorithm for a
replicated data store over an incomplete graph must satisfy. We
also reformulate the traditional properties – validity, integrity,
self-delivery, and reliability (or termination) – specified for a
complete graph in the literature for a replicated data store system
over an incomplete graph topology. We then analyze whether
Byzantine processes can mount attacks on these properties in our
two protocols. We show results for the classical communication
model and the local broadcast model.

IEEE NCA 2022

Byzantine Fault-Tolerant Causal Broadcast on Incomplete Graphs

wireless network

incomplete graph

causal broadcast

causal order

asynchronous message-passing

byzantine fault-tolerance

peer-to-peer

flooding

causality

### Welcome to IEEE NCA 2022!

NCA 2022, the International Symposium on Network Computing and Applications, is a successful series of conferences that serves as a large international forum for presenting and sharing recent research results and technological developments in the fields of Network and Cloud Computing. NCA, which is sponsored by the IEEE Computer Society, reaches out to both researchers and practitioners, and to both academia and industry. The conference features keynotes, technical presentations, and workshops.

All papers presented at the main conference and the workshops will be submitted to IEEE Xplore for publication and indexing.

[More about NCA](https://www.nca-ieee.org/2022/index.html)

**Organization**

* Steering Committee Chair: Dimiter R. Avresky, *IRIANC, Boston/Munich, USA/Germany*
* General Chair: Michele Colajanni, *University of Bologna, Italy*
* Program Chair: Miguel Pardal, *INESC-ID, Lisboa, Portugal*
* Program Chair: Luca Ferretti, *University of Modena and Reggio Emilia, Italy*
* Financial Chair: Mauro Andreolini, *University of Modena and Reggio Emilia, Italy*

**The topics of interest include, but are not limited to:**

* Theory of Network Computing
* Autonomic Network Computing
* Content Delivery Network (CDN)
* High Speed Networks/Protocols and Middleware
* Routing Mechanisms
* Overlay Networks/Peer-to-Peer Systems
* System Area Networks (SAN)/Clusters
* Performance Modeling/Quality of Services (QoS) Issues
* Web Caching and Switching
* Dependable Wide, Local, and System Area Networks
* Network Security
* Intrusion-Tolerant Networked Systems
* Scalable and Dependable Servers and Data Centers
* Middleware for Dependable Network Computing
* Self* (Configuring, Healing, Optimizing, Protecting, Organizing, Aware)
* Platforms for Network Computing
* Network Protocols: Verification and Validation
* Autonomic Network Computing for Achieving Self* Properties and Applications Availability
* Seamless and Virtual Capabilities for Implementing Self* Properties
* Software Defined Networking (SDN): Principles and Implementation
* Designing Highly-Available and Secure SDN
* Network Functions Virtualization (NFV): Design and Optimization
* Network Cloud Computing
* Machine Learning Techniques for Cloud Resources Management
* Big Data in Clouds for IoT
* Future Internet and Communicating Objects
* Mobile Ad-Hoc Networks (MANET)
* Sensor Networks
* Fog/Edge Computing
* Energy-Efficient Computation and Communication
* Applications to Real and/or Complex Problems, Practical Experiences and Prototypes
* Programming Environments for Distributed Systems
* Blockchain
* Byzantine Fault Tolerance
* Web and Mobile Security
* Security of Networked Applications (including Automotive, Industrial and Cyberphysical Systems)


To access the IEEE NCA 2022 content, [please register here ](https://www.nca-ieee.org/2022/registration.html)

NCA 2022, the International Symposium on Network Computing and Applications, is a successful series of conferences that serves as a large international forum for presenting and sharing recent research results and technological developments in the fields of Network and Cloud Computing.

technical paper

Detecting causality or the happens before relation
between events in an asynchronous distributed system is a
fundamental building block for distributed applications. To the
best of our knowledge, this problem has not been examined in a
system with Byzantine processes. We prove the following results
for an asynchronous system with Byzantine processes. (1) We
prove that it is impossible to determine causality between events
in the presence of even a single Byzantine process when processes
communicate by unicasting. (2) We also prove a similar impossibility
result when processes communicate by broadcasting.
(3) We also prove a similar impossibility result when processes
communicate by multicasting. (4) In an execution where there
exists a causal path between two events passing through only
correct processes, the impossibility result for unicasts remains. (5)
However, when processes communicate by broadcasting and there
exists a causal path between two events passing through only
correct processes, it is possible to detect causality between such
a pair of events. (6) In an execution where processes communicate
by multicasting and there exists a causal path between two
events passing through only correct processes, we prove that the
impossibility result for multicasts remains.

Detecting Causality in the Presence of Byzantine Processes: There is No Holy Grail

Nowadays, tourists turn to digital platforms to discover new places to explore. CROSS City is a smart tourism mobile application that enhances the user experience of tourists visiting points of interest in a route by rewarding them in the end, if they actually visited all locations. From a technical standpoint, the user location is certified resorting to strategies that take advantage of both the diversity of the existing Wi-Fi network infrastructure throughout the city, as well as the presence of other users at the same site using Bluetooth. This work developed a new, peer-to-peer location certification strategy and added gamification elements to encourage users to keep the wireless radios turned on and use the app more. This work was evaluated both in laboratory experiments and with users in a real-world scenario which demonstrated that the new Bluetooth peer-based strategy is both feasible and resistant to collusion attacks.

Bluetooth Peer-to-Peer Location Certification with a Gamified Mobile Application

In this work we present a set of issues affecting the research topic of cybersecurity on in-vehicle networks and we publicly address them by comparing three selected works against the same attack scenarios available in public datasets.

Comparison of Machine Learning-based anomaly detectors for Controller Area Network

Industrial plants are adopting an increasing number of digital interconnected technologies that are enriched by several software applications. The IT/OT convergence offers several benefits in terms of efficiency and flexibility but it opens as many issues in terms of cyber vulnerabilities because industrial plants were not designed to be open to Internet. The frequency of successful cyber attacks shows that typical security solutions are inadequate to the novel complexity of industrial contexts. This novel scenario requires original approaches differing from tradi- tional multi-layer networking solutions that are applicable just to rigid and stable infrastructures. We explore the applicability of Zero Trust Architecture (ZTA) principles to the industrial context by designing, implementing and testing an integrated defensive solution. The results obtained through a working prototype show that it is possible to implement a Zero Trust identity-centric approach in an industrial context to increase the security and flexibility of the system while providing complete visibility over the entire network. The proposed approach can be used to strengthen legacy industrial systems that were designed for offline use, and to allow the adoption of innovative technologies that minimize the cyber risk for the overall infrastructure.

A Zero Trust approach for the cybersecurity of Industrial Control Systems

A new CRT-based secret-sharing scheme with perfect information-theoretic (PIT) security and multiplicative homomorphism is presented. Given some background and references to related works.

Multiplicative Partially Homomorphic CRT Secret Sharing

This paper demonstrates and proves that the coordination of actions in a distributed swarm can be enhanced by using quantum entanglement. In particular, we focus on
• Global and local simultaneous random walks, using entangled qubits that collapse into the same (or opposite) direction, either random direction or totally controlled simultaneous movements.
• Identifying eavesdropping from malicious eavesdroppers aimed at disturbing the simultaneous random walks by using entangled qubits that were sent at random or with predefined bases

Distributed Coordination Based on Quantum Entanglement(Work in Progress)

"Abstract—Collaborative secure image matching is a problem
that is applicable in various domains, for both – data in rest
and data in motion. The problem is defined as follows. There
is a secret image, and a set of n mobile agents. The set of
mobile agents should match (compare) an observed image to
the original secret image. In this paper we discuss some of the
existing approaches, and present an alternative solution applied
and analyzed for different applications. The first application is
a swarm of Unmanned Aerial Vehicles (UAV) that search for
a target specified by an image. The second application is a
social network that serves as a smart storage device capable
of performing distributed, secret image matching operations.
Our solution is based on the well-known Visual Encryption
Scheme (VES) and projections of visual bit maps rather than
(quadratic complexity) messages exchange in implementing Se-
cure Multi Party Computation (MPC) scheme. We present a
perfect-information-theoretic secure solution for this problem.
To keep the original image secrecy, at least k out of n mobile
agents are required to retrieve any information about the original
image."

Swarming with (Visual) Secret (Shared) Mission

Modern browser technologies allow running highly portable and usable complex applications. However, the inability to access all the operating system features may limit their features or performance when compared to native software in certain scenarios. We investigate the design of peer-to-peer (P2P) networks of interconnected browsers to improve applications interconnecting users, such as videotelephony, messaging and gaming. Although peer-to-peer protocols are well-established in the literature, known designs and implementations cannot be executed on browsers due to constraints of browser environments. We propose WebDHT, a webassembly library for creating P2P networks among browsers which offers topic-based peerdiscovery features and integrates usable identity authentication mechanisms. WebDHT implements a variant of the Kademlia protocol based on distributed hash tables (DHT) adapted to support WebRTC protocol. WebDHT requires a native server to be available only for network bootstrap, but leverages existing browsers connected to the DHT to decentralize WebRTC signaling backends. We propose an open-source implementation and two demonstrative applications for users messaging and  multimedia streaming, and analyze limitations and future work for designing better browser-compatible P2P networks.

WebDHT: browser-compatible distributed hash table for decentralized Web applications

"Millions of tourists each year use smartphone applications to discover points of interest. Despite relying heavily on location sensing, most of them are susceptible to location spoofing, but not all. CROSS City is a smart tourism application that rewards users for completing tourist itineraries and uses location certificates to prevent attacks. In this case, the location verification relies on the periodic collection of public Wi-Fi network observations by multiple users to make sure the travelers actually went to the points of interest.
In this paper, we introduce the Location-Certification-as-aService (LoCaaS) approach, supported by a cloud-native and improved location certification system, capable of producing and validating time-bound location proofs using network data collected by tourists’ mobile devices. We show that the system can efficiently compute the stable and transient networks for a given location that are used, respectively, to validate the location of a tourist and to prove the time-of-visit. The system was deployed to the Google Cloud Platform and was validated with performance experiments and a real-world deployment.
"

LoCaaS: Location-Certification-as-a-Service

"Location is an important attribute for many mobile applications but it needs to be verified. For example, a user of a tourism application that gives out rewards can falsify his location to pretend that he has visited many attractions and thus receive benefits without deserving them. To counter these attacks, the system asks users to prove their location through witnesses, i.e.,other devices that happen to be at the location at the same time and that can be partially trusted. However, for this approach to be effective, it is important to keep track of the witness behavior over time. Many crowdsourcing applications, like Waze, build up reputations for their users, and rely on user co-location and redundant inputs for data verification.
In this work, we present SureRepute, a reputation system capable of withstanding reputation attacks while still maintaining user privacy. The results show that the system is able to protect itself and its configuration is flexible, allowing different trade-offs between security and usability, as required in realworld applications. The experiments show how the reputation system can be easily integrated into existing applications without producing a significant overhead in response times"

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Detecting Causality in the Presence of Byzantine Processes: There is No Holy Grail

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