For decentralised P2P networks, it is very important to have a mechanism in place that allows the nodes to control resource usage and prevent flooding and denial-of-service attacks with spam. In this paper, we discuss and compare the different approaches to fully decentralised resource control that are used by projects in the cryptocurrency space. The introduced methods are then applied to design a decentralised exchange for Namecoin names (or more generally, crypto assets) as an example.
It’s has been years and we still have a lot of downtimes in the major online platforms we use. When we go deep down and understand the problem, it’s all because of SPOF i. e. Single point of failure (which is a part of a system that, if it fails, it will stop the entire system from working). By this there is a possibility of downtime or hack or tampering of data or loss of data. Bitcoin is the first application of blockchain, then a lot of communities like Ethereum , etc. have been developing dApp protocols and frameworks to build applications in blockchain. Also a world renowned framework called Hyperledger Project is also in development made by an open source community consisting of people from large organisations. Early days and also now we have been using a technology called Torrent which is also decentralized. And now the question why to use decentralized systems in regards of issues with the largest social media company the problem was with the data that it had stored. Imagine a network that gives you the full control and privacy of data you share, send and get. Also not having a single second of service unavailability. The main aim of the project is to build a database system to achieve the goal of decentralized internet.
In recent years, Bitcoin, Ethereum and other cryptocurrencies have attracted a great deal of attention from the whole industry including the financial as a new settlement system. Transaction information of these cryptocurrencies is stored in a distribution ledger called Blockchain on the P2P network through processing such as PoW. Meanwhile, since PoW requires a large amount of computer resources, researches on private / consortium type blockchain that do not need PoW. In this paper, we propose a decentralized netting protocol using a consortium type block chain that has the channel function. On a system that implements the proposed protocol, netting settlement can be performed on P2P hiding information of the sender and receiver name of transaction, amount of money, calculation butt of netting, and without setting up a specific central organization such as a central server.
Among the various challenges faced by the P2P file sharing systems like BitTorrent, the most common attack on the basic foundation of such systems is: Free-riding. Generally, free-riders are the users in the file sharing network who avoid contributing any resources but tend to consume the resources unethically from the P2P network whereas white-washers are more specific category of free-riders that voluntarily leave the system in a frequent fashion and appearing again and again with different identities to escape from the penal actions imposed by the network. BitTorrent being a collaborative distributed platform requires techniques for discouraging and punishing such user behavior. In this paper, we propose that “Instead of punishing, we may focus more on rewarding the honest peers”. This approach could be presented as an alternative to other mechanisms of rewarding the peers like tit-for-tat [10], reciprocity based etc., built for the BitTorrent platform. The prime objective of BitTrusty is: providing incentives to the cooperative peers by rewarding in terms of cryptocoins based on blockchain. We have anticipated three ways of achieving the above defined objective. We are further investigating on how to integrate these two technologies of distributed systems viz. P2P file sharing systems and blockchain, and with this new paradigm, interesting research areas can be further developed, both in the field of P2P cryptocurrency networks and also when these networks are combined with other distributed scenarios.
This paper explains how the distributed ledger technology that has successfully decentralized currencies can be used to enable a decentralized marketplace for digital content rights. Today, multiple centralized rights lockers from companies and consortiums offer similar but incompatible systems to register a consumer's video purchases and manage content rights. Each is representing a monopoly that centrally governs the content rights and is motivated to do so only for as long as it remains profitable. — Blockchain technology can be used to establish a permanent, secure, decentralized and distributed registry for content registration, assignment and archival of rights. The benefits of leveraging blockchain for video content distribution and content rights management provide longevity that is independent of a single standard, company or governance body as well as security of transactions with cryptographic guarantee of entitlements and grants of content licenses that cannot be changed and verified permanently. Lastly, the distributed and replicated nature of the peer-to-peer (P2P) network provides resiliency, eliminating a single point of failure as well as the need to rely on just one single standard, company or governance body. This paper will provide a novel system design that explains how a blockchain can be applied to not only manage content rights but to also secure content by including digital rights management (DRM) and playback control as an integral part of the decentralized network. It also details how to improve common ledger technology to overcome concerns of performance and abuse that are relevant to this application.
Sai Medury, Anthony Skjellum, Richard R. Brooks, Lu Yu
X.509 certificates underpin the security of the Internet economy, notably secure web servers, and they need to be revoked promptly and reliably once they are compromised. The original revocation method specified in the X.509 standard, to distribute certificate revocation lists (CRLs), is both old and untrustworthy. CRLs are susceptible to attacks such as Man-in-the-Middle and Denial of Service. The newer Online Certificate Status Protocol (OCSP) and OCSP-stapling approaches have well-known drawbacks as well. The primary contribution of this paper is Secure Revocation as a Peer Service (SCRaaPS). SCRaaPS is an alternative, reliable way to support X.509 certificate revocation via the Scrybe secure provenance system. The blockchain support of Scrybe enables the creation of a durable, reliable revocation service that can withstand Denial-of-Service attacks and ensures non-repudiation of certificates revoked. We provide cross-CA-revocation information and address the additional problem of intermediate-certificate revocation with the knock-on effects on certificates derived thereof. A Cuckoo filter provides quick, communication-free testing by servers and browsers against our current revocation list (with no false negatives). A further contribution of this work is that the revocation service can fit in as a drop-in replacement for OCSP-stapling with superior performance and coverage both for servers and browsers. Potential revocation indicated by our Cuckoo filter is backed up by rigorous service query to eliminate false positives. Cuckoo filter parameters are also stored in our blockchain to provide open access to this algorithmic option for detection. We describe the advantages of using a blockchain-based system and, in particular, the approach to distributed ledger technology and lightweight mining enabled by Scrybe, which was designed with secure provenance in mind.
Bitcoin has utilized Proof-of-Work(PoW), which prevents double-spend attack in the distributed network. PoW is a consensus protocol that depends on a computing power, therefore it is highly difficult for malicious nodes to attack. However, emerging a group called mining pool encourage the centralization of computing power. This may make it easy to tamper with a distributed ledger called Blockchain of Bitcoin.In this paper, we propose the new protocol which evaluates computing power for each nodes and adjusts difficulty of generating a block based on the evaluation. This gives an equal opportunity for successful mining. Furthermore, reward for user's incentive is also adjusted based on the evaluation.
Adja Elloh Yves-Christian, Badis Hammi, Ahmed Serhrouchni, Houda Labiod
In the cryptocurrency world, Bitcoin holds the first place in terms of market cap and currency price, which makes it the first target and victim of attack attempts. Indeed, there are various attacks against cryptocurrencies in general and Bitcoin in particular, e.g., block withholding, transaction malleability and the Eclipse attack. The latter, allows an attacker to completely isolate a peer and to monopolize all permanent connections from/to the victim. However, in this attack, the non permanent connections, remains non monopolized by the attacker, which can disturb the attack success. In this paper, we propose (1) a characterization of the misbehavior mechanism applied by Bitcoin and its weaknesses; and (2) a new method to realize the Eclipse attack which monopolizes all the peer's connections, even the non permanent ones, with a minimal number of IP addresses. Our characterization and attack realization, were performed on the main Bitcoin network and on a real client.
Bruno Andriamanalimanana, Chen-Fu Chiang, Jorge Novillo, Sam Sengupta · 5 authors
A central problem with distributed ledger technologies involves the latency that must be incurred in processing and verifying transactions to be accepted as permanent records in the ledger. In many applications, high latency is simply not a tolerable aspect of the governance of the ledger. To help reduce latency, we offer a distributed ledger architecture, Tango, that mimics the Iota-tangle design as articulated by Popov [1] in his seminal paper. A main idea is the introduction of a semi-synchronous transaction entry protocol layer. We model periodic pulsed injections into the evaluation layer from the entry layer.
Astrid Nieße, Norman Ihle, Stephan Balduin, Matthias Postina · 6 authors
Congestion management in distribution grids is an important task for distribution grid operators, both from a financial and a technological perspective. Whereas large generation units and large controllable loads might in general be controllable in a manual way, this is no option for small distributed generators and loads. With flexibility control in multiple owner scenarios, documentation, transparency and automation are of crucial importance. In this work, we present a fully automated congestion management approach based on a combination of distributed ledger technology and distributed algorithms in an agent-based architectural approach. We present a case study focused on the visualization of the concept and discuss the advantages and possible challenges for this approach. Whereas distributed ledger technology has been introduced for peer-to-peer energy trading within the last years, no similar approach has been presented yet for stable distribution grid management.
Blockchain has emerged as a trusted and secure distributed ledger for transactions while also being decentralised, distributed and its legitimacy not guaranteed by a trusted authority. Since the appearance of Bitcoin, Blockchain has known many implementations based on P2P architectures. This paper presents how the blockchain and smart contracts technologies can be integrated into the SwarmESB ecosystem. SwarmESB is a framework that helps building distributed applications, which benefit from privacy and scalability features. Our proposal will present the flexibility in building not only microservices based applications, but also decen-tralised applications employing blockchain and smart-contracts by modeling a sample Dapp.
Off-chain scaling techniques allow mutually distrustful parties to execute a contract locally among themselves instead of on the global blockchain. Parties involved in the transaction maintain a multi-signature fraud-proof off-chain replicated state machine, and only resort to on-chain consensus when absolutely necessary (e.g., when two parties disagree on a state). Off-chain scaling is the only way to support fully scale-out decentralized applications ("dApps") with better privacy and no compromise on the trust and decentralization guarantees. It is the inflection point for blockchain mass adoption, and will be the engine behind all scalable dApps. Celer Network is an Internet-scale, trust-free, and privacy-preserving platform where everyone can quickly build, operate, and use highly scalable dApps. It is not a standalone blockchain but a networked system running on top of existing and future blockchains. It provides unprecedented performance and flexibility through innovation in off-chain scaling techniques and incentive-aligned cryptoeconomics. Celer Network embraces a layered architecture with clean abstractions that enable rapid evolution of each individual component, including a generalized state channel and sidechain suite that supports fast and generic off-chain state transitions; a provably optimal value transfer routing mechanism that achieves an order of magnitude higher throughput compared to state-of-the-art solutions; a powerful development framework and runtime for off-chain applications; and a new cryptoeconomic model that provides network effect, stable liquidity, and high availability for the off-chain ecosystem.
Despite growing adoption of cryptocurrencies, making fast payments at scale remains a challenge. Payment channel networks (PCNs) such as the Lightning Network have emerged as a viable scaling solution. However, completing payments on PCNs is challenging: payments must be routed on paths with sufficient funds. As payments flow over a single channel (link) in the same direction, the channel eventually becomes depleted and cannot support further payments in that direction; hence, naive routing schemes like shortest-path routing can deplete key payment channels and paralyze the system. Today's PCNs also route payments atomically, worsening the problem. In this paper, we present Spider, a routing solution that "packetizes" transactions and uses a multi-path transport protocol to achieve high-throughput routing in PCNs. Packetization allows Spider to complete even large transactions on low-capacity payment channels over time, while the multi-path congestion control protocol ensures balanced utilization of channels and fairness across flows. Extensive simulations comparing Spider with state-of-the-art approaches shows that Spider requires less than 25% of the funds to successfully route over 95% of transactions on balanced traffic demands, and offloads 4x more transactions onto the PCN on imbalanced demands.
Permissionless blockchains reach decentralized consensus without requiring pre-established identities or trusted third parties, thus enabling applications such as cryptocurrencies and smart contracts. Consensus is agreed on data that is generated by the application and transmitted by the system's (peer-to-peer) network layer. While many attacks on the network layer were discussed so far, there is no systematic approach that brings together known attacks, the requirements, and the design space of the network layer. In this paper, we survey attacks on the network layer of permissionless blockchains, and derive five requirements: 1) performance; 2) low cost of participation; 3) anonymity; 4) DoS resistance; and 5) topology hiding. Furthermore, we survey the design space of the network layer and qualitatively show the effect of each design decisions on the fulfillment of the requirements. Finally, we pick two aspects of the design space, in-band peer discovery and relay delay, and demonstrate possible directions of future research by quantitatively analyzing and optimizing simplified scenarios. We show that while most design decisions imply certain tradeoffs, there is a lack of models that analyze and formalize these tradeoffs. Such models could aid the design of the network layer of permissionless blockchains. One reason for the lack of models is the deliberately limited observability of deployed blockchains. We emphasize that simulation based approaches cope with these limitations and are suited for the analysis of the network layer of permissionless blockchains.
Blockchain has received great attention in recent years and motivated innovations in different scenarios. However, many vital issues which affect its performance are still open. For example, it is widely convinced that high level of security and scalability and full decentralization are still impossible to achieve simultaneously. In this paper, we propose Bicomp, a bilayer scalable Nakamoto consensus protocol, which is an approach based on high security and pure decentralized Nakamoto consensus, and with a significant improvement on scalability. In Bicomp, two kinds of blocks are generated, i.e., microblocks for concurrent transaction packaging in network, and macroblocks for leadership competition and chain formation. A leader is elected at beginning of each round by using a macroblock header from proof-of-work. An elected leader then receives and packages multiple microblocks mined by different nodes into one macroblock during its tenure, which results in a bilayer block structure. Such design limits a leader's power and encourages as many nodes as possible to participate in the process of packaging transactions, which promotes the sharding nature of the system. Furthermore, several mechanisms are carefully designed to reduce transaction overlapping and further limit a leader's power, among which a novel transaction diversity based metric is proposed as the second level criteria besides the longest-chain-first principle on selecting a legitimate chain when fork happens. Security issues and potential attacks to Bicomp are extensively discussed and experiments for evaluation are performed. From the experimental results based on 50 nodes all over the world, Bicomp achieves significant improvement on scalability than that of Bitcoin and Ethereum, while the security and decentralization merits are still preserved.
Blockchain is based on a P2P network, supporting decentralized consensus of current cryptocurrencies. Since bitcoin and altcoins all utilize an underlying blockchain, they are therefore greatly affected by the performance of the P2P network. In bitcoin, the miners are engaged in a time-sensitive competition to solve a Proof-of-Work problem to extend the blockchain. This consequently raises a critical problem to minimize the time between the propagation of a winning block and the beginning of the next round of the competition. This paper proposes a method that selects a node's closest neighbors to make messages propagate in the whole network in time. The method measures the distance from a node to its neighbor using transmission latency; thus, the lower the latency, the closer the neighbor. Simulations showed a good rate of decrease in average propagation latency and maximum propagation latency, compared to the classic method. Furthermore, this paper not only proposes the principle of establishing connections based on latency, but also evaluates the influence of the number of simultaneously established connections.
A wide range of services and applications can be improved and/or solved by\nusing distributed ledger technology (DLT). These services and applications have\nwidely varying quality of service (QoS) requirements. However, most existing\nDLT systems do not distinguish different QoS requirements, resulting in\nsignificant performance issues such as poor scalability and high cost. In this\nwork, we present vDLT -- a service-oriented blockchain system with\nvirtualization and decoupled management/control and execution. In vDLT,\nservices and applications are classified into different classes according to\ntheir QoS requirements, including confirmation latency, throughput, cost,\nsecurity, privacy, etc. This is a paradigm shift from the existing\n"blockchain-oriented" DLT systems to next generation "service-oriented" DLT\nsystems. Different QoS requirements are fulfilled by advanced schemes inspired\nby the development of the traditional Internet, including classification,\nqueuing, virtualization, resource allocation and orchestration, and\nhierarchical architecture. In addition, management/control and execution of\nsmart contracts are decoupled to support QoS provisioning, improve\ndecentralization, and facilitate evolution in vDLT. With virtualization,\ndifferent virtual DLT systems with widely varying characteristics can be\ndynamically created and operated to accommodate different services and\napplications.\n
In this article, we study ongoing blockchain and distributed ledger technologies (DLT) standardization. To this end, we list standards organizations and the efforts they devote to standardise blockchain and DLT. We then identify a lack of terminology that can hamper communication on this topic and propose clarifications to address these ambiguities. Finally, we propose a high-level description of blockchain and DLT by describing three elements of their functional architecture.
Price stability has often been cited as a key reason that cryptocurrencies\nhave not gained widespread adoption as a medium of exchange and continue to\nprove incapable of powering the economy of decentralized applications (DApps)\nefficiently. Exeum proposes a novel method to provide price stable digital\ntokens whose values are pegged to real world assets, serving as a bridge\nbetween the real world and the decentralized economy.\n Pegged tokens issued by Exeum - for example, USDE refers to a stable token\nissued by the system whose value is pegged to USD - are backed by virtual\nassets in a virtual asset exchange where users can deposit the base token of\nthe system and take long or short positions. Guaranteeing the stability of the\npegged tokens boils down to the problem of maintaining the peg of the virtual\nassets to real world assets, and the main mechanism used by Exeum is\ncontrolling the swap rate of assets. If the swap rate is fully controlled by\nthe system, arbitrageurs can be incentivized enough to restore a broken peg;\nExeum distributes statistical arbitrage trading software to decentralize this\ntype of market making activity. The last major component of the system is a\ncentral bank equivalent that determines the long term interest rate of the base\ntoken, pays interest on the deposit by inflating the supply if necessary, and\nremoves the need for stability fees on pegged tokens, improving their\nusability.\n To the best of our knowledge, Exeum is the first to propose a truly\ndecentralized method for developing a stablecoin that enables 1:1 value\nconversion between the base token and pegged assets, completely removing the\nmismatch between supply and demand. In this paper, we will also discuss its\napplications, such as improving staking based DApp token models, price stable\ngas fees, pegging to an index of DApp tokens, and performing cross-chain asset\ntransfer of legacy crypto assets.\n
This thesis focuses on aspects related to the functioning of the gossip\nnetworks underlying three relatively popular cryptocurrencies: Ethereum, Nano\nand IOTA.\n We look at topics such as automatic discovery of peers when a new node joins\nthe network, bandwidth usage of a node, message passing protocols and storage\nschemas and optimizations for the shared ledger. We believe this is a topic\nthat is often overlooked in works about blockchains and cryptocurrencies.\nVulnerabilities and inefficiencies attain a higher significance than ones in a\nregular open source project because of the rather direct financial implications\nof these projects. Barring Bitcoin, a network that has been around for nearly\n10 years, no other project has substantial documentation for its operational\ndetails other than scattered and sparse pages in the source code repositories.\nAlmost all of the content described here has been extracted by studying the\nsource code of the reference implementations of these projects.\n We evaluate the use of Invertible Bloom Lookup Tables and the Graphene\nprotocol to decrease block propagation times and bandwidth usage of certain\nmessages. We perform realistic simulations that show significant improvements.\nWe provide a complete implementation of Graphene in Geth, Ethereum's main node\nsoftware and test this implementation against the main Ethereum blockchain.\n We also crawled the chosen cryptocurrency networks for publicly visible nodes\nand provide an Autonomous System-level breakdown of these nodes with the end\ngoal of estimating the ease of performing attacks such as BGP hijacks and their\nimpact.\n Code written for implementing Graphene in Geth, performing various\nsimulations and for other miscellaneous tasks has been uploaded to Github at\nhttps://github.com/sunfinite/masters-thesis.\n
Blockchain and smart contract provide a convenient vehicle to build decentralize applications. Among varies Decenrtalized applications (DAPPs), exchange is one of the most mentioned ones. To fully-decentralized an exchange looks somehow like an utopia. Most works tried to use different methods to solve different problems on this subject. According to our observations, the problems caused by blockchain include 1) Long confirmation time, 2) Vulnerable to front running attack, 3) wasting on-chain resource, all these problems make a blockchain based exchange not user friendly. To deal with the above-mentioned problems, a hybrid centralized and decentralized exchange is presented in this work. By simulating the transaction execution processes and eliminating all the unwanted uncertainties, we are confident that the transactions in the proposed exchange center (EC) will be confirmed and executed well on the blockchain, that is, our system allows users to conclude their trades without need of waiting for a long blockchain confirmation time. In conclusion, a Hybrid Centralized and Decentralized Application (HCDAPP) provides a better-quality service, just like a centralized server; at the same time, it also provides a higher-level security, like a decentralized smart contract.
Upon flaws of current blockchain platforms of heavyweight, large capacity of ledger, and time-consuming of synchronization of data, in this paper, we proposed a new paradigm of master-slave blockchain scheme (MSB) for pervasive computing that suitable for general PC, mobile device such as smart phones or PADs to participants in the working of mining and verification, in which we separated traditional blockchain model in 2 layer defined as master node layer and a series of slavery agents layer, then we proposed 2 approaches for partially computing model(P-CM) and non-computing of model(NCM) in the MSB blockchain, Finally large amounts of simulations manifest the proposed master-slave blockchain scheme is feasible, extendible and suitable for pervasive computing especially in the 5G generation environment, and can apply in the DRM-related applications.
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
Ee Hong Aw, Ralucca Gera, Kenneth S. Hicks, Nicholas Koeppen · 5 authors
Due to the anonymous and remote nature of Electronic Commerce (E-commerce), reviews of products and vendors left by previous customers have emerged as an integral part of most online transactions. The reviews may influence the decision of customers buying the product since E-commerce websites/services do not allow customers to validate and inspect products in-store. In this paper, we analyze data from two BITCOIN marketplaces which include transactions between marketplace users and the ratings of those transactions given by those users. In this analysis we create a synthetic network model with similar topological properties as the networks of the interactions of both marketplaces. The results of our analysis show an interesting phenomenon in which user ratings, which range from -10 to 10, converge to a value of approximately two as the number of a user's transactions increase. Finally, we suggest future work on our synthetic model to improve its agreement with the transaction networks in order to better understand how reviews influence user decisions on transactions.