Privacy-Preserving Trust Management Mechanisms from Private Matching Schemes

Cryptographic primitives are essential for constructing privacy-preserving communication mechanisms. There are situations in which two parties that do not know each other need to exchange sensitive information on the Internet. Trust management mechanisms make use of digital credentials and certificates in order to establish trust among these strangers. We address the problem of choosing which credentials are exchanged. During this process, each party should learn no information about the preferences of the other party other than strictly required for trust establishment. We present a method to reach an agreement on the credentials to be exchanged that preserves the privacy of the parties. Our method is based on secure two-party computation protocols for set intersection. Namely, it is constructed from private matching schemes.Comment: The material in this paper will be presented in part at the 8th DPM International Workshop on Data Privacy Management (DPM 2013

Privacy-Preserving Multi-Party Reconciliation Secure in the Malicious Model (Extended version)

The problem of fair and privacy-preserving ordered set reconciliation arises in a variety of applications like auctions, e-voting, and appointment reconciliation. While several multi-party protocols have been proposed that solve this problem in the semi-honest model, there are no multi-party protocols that are secure in the malicious model so far. In this paper, we close this gap. Our newly proposed protocols are shown to be secure in the malicious model based on a variety of novel non-interactive zero-knowledge-proofs. We describe the implementation of our protocols and evaluate their performance in comparison to protocols solving the problem in the semi-honest case

DIGITAL ASSETS TRANSMISSION BETWEEN ORGANIZATIONS: MUSIC INDUSTRY CASE

This research addresses the following experiences as a contribution to the topic of Blockchain applications. First, the modeling of a Music Industry revenue distribution problem. Second, the Integration of Blockchain platforms and Legacy software. Third, the design of an algorithm that solves the distribution of Digital Assets across organizations within the Music Industry. Ultimately, the analysis of the Performance of Blockchain platforms (Ethereum and Hyperledger) in terms of Latency and Throughput. Additionally, the purpose of the research is to show that the modeling of a Music Industry payment system is possible using Blockchain Technology. Therefore, the old business model of the Music Industry, which possessed flaws and inefficiencies, could potentially change into a trustless environment benefiting all the participants y paying their contributions instantaneously. Moreover, the necessity of a solution is reinforced by an internship experienced in a MITACS project in conjunction with a company called Membran to design and implement a Blockchain solution that shortens the gap between Spotify and the payment to the Labels and Artists. The system distributes value by automatically calculating payments whenever the Digital Assets (Music Tracks revenue) are imported. The application defines specific roles and variables to simulate the Music Industry. For example, Distributors as an entry point and Artists at the end of the chain. Although, any participant within the network can create agreements and benefit from the distribution. The implementation of this research took the Hyperledger Composer framework to use the Hyperledger Fabric Blockchain as the Private Distributed Ledger, and the public Blockchain Ethereum with the Ganache Client for development purposes. Extensive research of the strengths and weaknesses of these technologies included the descriptions of features like the consensus algorithms, modular architectures, and smart contracts. Ultimately, the performance of these technologies compared Hyperledger Composer and Ethereum in terms of Latency and Throughput. The conclusion of this research pointed that Hyperledger Composer with features like the role-based architecture for applications, Programmable ChainCode (Smart Contracts), and Business Network Definitions, is better suitable for modeling customized solutions and outperforms Ethereum in terms of performance when testing the same number of transactions, the same logic of the chain code and the same machine environment

Scalable string reconciliation by recursive content-dependent shingling

We consider the problem of reconciling similar strings in a distributed system. Specifically, we are interested in performing this reconciliation in an efficient manner, minimizing the communication cost. Our problem applies to several types of large-scale distributed networks, file synchronization utilities, and any system that manages the consistency of string encoded ordered data. We present the novel Recursive Content-Dependent Shingling (RCDS) protocol that can handle large strings and has the communication complexity that scales with the edit distance between the reconciling strings. Also, we provide analysis, experimental results, and comparisons to existing synchronization software such as the Rsync utility with an implementation of our protocol.2019-12-03T00:00:00

Improving Data Availability in Decentralized Storage Systems

PhD thesis in Information technologyPreserving knowledge for future generations has been a primary concern for humanity since the dawn of civilization. State-of-the-art methods have included stone carvings, papyrus scrolls, and paper books. With each advance in technology, it has become easier to record knowledge. In the current digital age, humanity may preserve enormous amounts of knowledge on hard drives with the click of a button. The aggregation of several hard drives into a computer forms the basis for a storage system. Traditionally, large storage systems have comprised many distinct computers operated by a single administrative entity. With the rise in popularity of blockchain and cryptocurrencies, a new type of storage system has emerged. This new type of storage system is fully decentralized and comprises a network of untrusted peers cooperating to act as a single storage system. During upload, files are split into chunks and distributed across a network of peers. These storage systems encode files using Merkle trees, a hierarchical data structure that provides integrity verification and lookup services. While decentralized storage systems are popular and have a user base in the millions, many technical aspects are still in their infancy. As such, they have yet to prove themselves viable alternatives to traditional centralized storage systems. In this thesis, we contribute to the technical aspects of decentralized storage systems by proposing novel techniques and protocols. We make significant contributions with the design of three practical protocols that each improve data availability in different ways. Our first contribution is Snarl and entangled Merkle trees. Entangled Merkle trees are resilient data structures that decrease the impact hierarchical dependencies have on data availability. Whenever a chunk loss is detected, Snarl uses the entangled Merkle trees to find parity chunks to repair the lost chunk. Our results show that by encoding data as an entangled Merkle tree and using Snarl’s repair algorithm, the storage utilization in current systems could be improved by over five times, with improved data availability. Second, we propose SNIPS, a protocol that efficiently synchronizes the data stored on peers to ensure that all peers have the same data. We designed a Proof of Storage-like construction using a Minimal Perfect Hash Function. Each peer uses the PoS-like construction to create a storage proof for those chunks it wants to synchronize. Peers exchange storage proofs and use them to efficiently determine which chunks they are missing. The evaluation shows that by using SNIPS, the amount of synchronization data can be reduced by three orders of magnitude in current systems. Lastly, in our third contribution, we propose SUP, a protocol that uses cryptographic proofs to check if a chunk is already stored in the network before doing wasteful uploads. We show that SUP may reduce the amount of data transferred by up to 94 % in current systems. The protocols may be deployed independently or in combination to create a decentralized storage system that is more robust to major outages. Each of the protocols has been implemented and evaluated on a large cluster of 1,000 peers

Challenges in family law

Meeting proceedings of a seminar by the same name, held December 16, 2020

A P2P Networking Simulation Framework For Blockchain Studies

Recently, blockchain becomes a disruptive technology of building distributed applications (DApps). Many researchers and institutions have devoted their resources to the development of more effective blockchain technologies and innovative applications. However, with the limitation of computing power and financial resources, it is hard for researchers to deploy and test their blockchain innovations in a large-scape physical network. Hence, in this dissertation, we proposed a peer-to-peer (P2P) networking simulation framework, which allows to deploy and test (simulate) a large-scale blockchain system with thousands of nodes in one single computer. We systematically reviewed existing research and techniques of blockchain simulator and evaluated their advantages and disadvantages. To achieve generality and flexibility, our simulation framework lays the foundation for simulating blockchain network with different scales and protocols. We verified our simulation framework by deploying the most famous three blockchain systems (Bitcoin, Ethereum and IOTA) in our simulation framework. We demonstrated the effectiveness of our simulation framework with the following three case studies: (a) Improve the performance of blockchain by changing key parameters or deploying new directed acyclic graph (DAG) structure protocol; (b) Test and analyze the attack response of Tangle-based blockchain (IOTA) (c) Establish and deploy a new smart grid bidding system for demand side in our simulation framework. This dissertation also points out a series of open issues for future research

Synchronization of data in heterogeneous decentralized systems

Data synchronization is the problem of reconciling the differences between large data stores that differ in a small number of records. It is a common thread among disparate distributed systems ranging from fleets of Internet of Things (IoT) devices to clusters of distributed databases in the cloud. Most recently, data synchronization has arisen in globally distributed public blockchains that build the basis for the envisioned decentralized Internet of the future. Moreover, the parallel development of edge computing has significantly increased the heterogeneity of networks and computing devices. The merger of highly heterogeneous system resources and the decentralized nature of future Internet applications calls for a new approach to data synchronization. In this dissertation, we look at the problem of data synchronization through the prism of set reconciliation and introduce novel tools and protocols that improve the performance of data synchronization in heterogeneous decentralized systems. First, we compare the analytical properties of the state-of-the-art set reconciliation protocols, and investigate the impact of theoretical assumptions and implementation decisions on the synchronization performance. Second, we introduce GenSync, the first unified set reconciliation middleware. Using GenSync's distinctive benchmarking layer, we find that the best protocol choice is highly sensitive to the system conditions, and a bad protocol choice causes a severe hit in performance. We showcase the evaluative power of GenSync in one of the world's largest wireless network emulators, and demonstrate choosing the best GenSync protocol under a high and low user mobility in an emulated cellular network. Finally, we introduce SREP (Set Reconciliation-Enhanced Propagation), a novel blockchain transaction pool synchronization protocol with quantifiable guarantees. Through simulations, we show that SREP incurs significantly smaller bandwidth overhead than a similar approach from the literature, especially in the networks of realistic sizes (tens of thousands of participants)

A Critical Investigation into Identifying Key Focus Areas for the Implementation of Blockchain Technology in the Mining Industry

Thesis (PhD)--University of Pretoria, 2023.The value of digital information is ever-increasing as more companies utilize digital technologies such as Artificial Intelligence (AI) and the Internet of Things (IoT) to gain deeper insight into their business operations and drive productivity gains. It is therefore important to safeguard and ensure the integrity of digital information exchange. Blockchain technology (BCT) was identified as potentially providing the mining industry with a trusted system for securely exchanging digital value. However, there is little evidence or understanding of how/where BCT can be implemented and what benefits the industry could obtain. This research study provides a fundamental understanding of what the technology is in order to identify the associated capabilities and potential application benefits for the mining industry. From a technology push perspective, blockchain capabilities are used to evaluate how the technology’s value drivers map to the mining industries core value chain processes. This was done to identify potential focus areas within the mining enterprise for further research and development of blockchain applications.ARMMining EngineeringMEngUnrestricte