U ovom završnom radu obrađen je pojam hardvera za rudarenje kriptovaluta. Nakon uvoda u prvom poglavlju opisana je prva kriptovaluta "Bitcoin". U drugom poglavlju objašnjen je protokol "Blockchain" na koji Bitcoin funkcionira. U trećem poglavlju opisane su transakcije, te posao rudara u bitcoin mreži. U četvrtom poglavlju je opisana povijest hardvera, te detaljan opis hardvera ovisno o generaciji. U zadnjem poglavlju je opisan suvremeni hardver te najbolje rješenje za Bitcoin i Ethereum, drugu najvrjedniju kriptovalutu.
Mustafa Al-Bassam, Alberto Sonnino, Vitalik Buterin
Light clients, also known as Simple Payment Verification (SPV) clients, are nodes which only download a small portion of the data in a blockchain, and use indirect means to verify that a given chain is valid. Typically, instead of validating block data, they assume that the chain favoured by the blockchain's consensus algorithm only contains valid blocks, and that the majority of block producers are honest. By allowing such clients to receive fraud proofs generated by fully validating nodes that show that a block violates the protocol rules, and combining this with probabilistic sampling techniques to verify that all of the data in a block actually is available to be downloaded, we can eliminate the honest-majority assumption, and instead make much weaker assumptions about a minimum number of honest nodes that rebroadcast data. Fraud and data availability proofs are key to enabling on-chain scaling of blockchains (e.g. via sharding or bigger blocks) while maintaining a strong assurance that on-chain data is available and valid. We present, implement, and evaluate a novel fraud and data availability proof system.
Mustafa Al-Bassam, Alberto Sonnino, Vitalik Buterin
Light clients, also known as Simple Payment Verification (SPV) clients, are\nnodes which only download a small portion of the data in a blockchain, and use\nindirect means to verify that a given chain is valid. Typically, instead of\nvalidating block data, they assume that the chain favoured by the blockchain's\nconsensus algorithm only contains valid blocks, and that the majority of block\nproducers are honest. By allowing such clients to receive fraud proofs\ngenerated by fully validating nodes that show that a block violates the\nprotocol rules, and combining this with probabilistic sampling techniques to\nverify that all of the data in a block actually is available to be downloaded,\nwe can eliminate the honest-majority assumption, and instead make much weaker\nassumptions about a minimum number of honest nodes that rebroadcast data. Fraud\nand data availability proofs are key to enabling on-chain scaling of\nblockchains (e.g. via sharding or bigger blocks) while maintaining a strong\nassurance that on-chain data is available and valid. We present, implement, and\nevaluate a novel fraud and data availability proof system.\n
Sep 22, 2018·2018 IEEE SmartWorld, Ubiquitous Intelligence & Computing, Advanced & Trusted Computing, Scalable Computing & Communications, Cloud & Big Data Computing, Internet of People and Smart City Innovation
Bitcoin, as a decentralized digital currency, has caused extensive research interest. There are many studies based on related protocols on Bitcoin, Bitcoin-based voting protocols also received attention in related literature. In this paper, we propose a Bitcoin-based decentralized privacy-preserving voting mechanism. It is assumed that there are n voters and m candidates. The candidate who obtains t ballots can get x Bitcoins from each voter, namely nx Bitcoins in total. We use a shuffling mechanism to protect voter's voting privacy, at the same time, decentralized threshold signatures were used to guarantee security and assign voting rights. The protocol can achieve correctness, decentralization and privacy-preservings. By contrast with other schemes, our protocol has a smaller number of transactions and can achieve a more functional voting method.
Without the design for inherent security, the Border Gateway Protocol (BGP) is vulnerable to prefix/subprefix hijacks and other attacks. Though many BGP security approaches have been proposed to prevent or detect such attacks, the unsatisfactory cost-effectiveness frustrates their deployment. In fact, the currently deployed BGP security infrastructure leaves the chance for potential centralized authority misconfiguration and abuse. It actually becomes the critical yield point that demands the logging and auditing of misbehaviors and attacks in BGP security deployments. We propose a blockchain-based Internet number resource authority and trustworthy management solution, named BGPcoin, to facilitate the transparency of BGP security. BGPcoin provides a reliable origin advertisement source for origin authentication by dispensing resource allocations and revocations compliantly against IP prefix hijacking. We perform and audit resource assignments on the tamper-resistant Ethereum blockchain by means of a set of smart contracts, which also interact as one to provide the trustworthy origin route examination for BGP. Compared with RPKI, BGPcoin yields significant benefits in securing origin advertisement and building a dependable infrastructure for the object repository. We demonstrate it through an Ethereum prototype implementation, and we deploy it and do experiment on a locally-simulated network and an official Ethereum test network respectively. The extensive experiment and evaluation demonstrate the incentives to deploy BGPcoin, and the enhanced security provided by BGPcoin is technically and economically feasible.
Building a secure electronic voting system is a difficult task. The US Pentagon dropped their proposed online voting system which would have given overseas military personnel the opportunity to vote in the elections in 2005, citing the inability to ensure the legitimacy of votes as the reason. There is however a new cry in the wild to deploy a voting blockchain. The blockchain serves as a public ledger of transactions which cannot be reversed. The all-important consensus of transaction (i.e. legitimate votes) is achieved through 'miners' agreeing to validate new records being added. Whenever a new insertion is to be made e.g. votes, then a new transaction record is created by a voter adding details of their cast vote to the blockchain. Should it be deemed a valid transaction then the new vote is added to the end of the blockchain and remains there forever. What is neat about this solution is the fact that no centralized authority is needed to approve the votes but rather a majority consensus. Here everyone agrees on the final tally as they can count the votes themselves & because of the blockchain audit trail, anyone can verify that no votes were tampered with and no illegitimate votes were inserted. This paper discusses the application of blockchain to voting.
Current electronic voting protocol require a centralized system to control the whole procedure from ballot inputs to result outputs and election monitoring. Meanwhile, blockchain technology provide a decentralized system which open across the whole network of untrusted participants. Applying blockchain technology into electronic voting protocol through a proper architecture can instil characteristic such as data confidentiality, data integrity and data authenticity. In this paper, we going to discuss a proposed method on how to leverage the advantages from blockchain into electronic voting protocol. This blockchain-based electronic voting protocol promise to provide a secure electronic election process given the proposed system works. We implement a protocol using blockchain to turn election protocol into an automated control system without relying any single point of entity. Lastly, we discuss the characteristics of our proposed blockchain-based electronic voting protocol in this paper. However, there are also emerging challenges and limitations awaiting to overcome. This paper gives a comprehensive overview of our proposed protocol.
Open access
Internet Traffic Analysis and Secure E-voting
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
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.
In the Bitcoin blockchain, rewarding methods for remunerating miners participating in a pool have to meet certain requirements in order to guarantee the proper functioning of the cryptocurrency ecosystem. In particular, these allocation rules reward pool participants in proportion to their contribution in the transaction validation process. Deployed rewarding methods met fairness concerns at the expense of vulnerability to miners exploiting pools' attractiveness for deciding when to mine for a pool and when to `hop' to another one resulting more attractive: a phenomenon called pool-hopping. The most used score-based methods are designed to prevent this practice, but are not completely hopping proof. In this work, we propose a methodology to analyze the pool-hopping phenomenon, focusing on the detection of pool-hoppers. Analyzing those Bitcoin transactions that pools create for rewarding its participants, it is possible to determine time epochs where miners worked. Thus, we analyze those miners that have worked intermittently for pools adopting a rewarding system which pays out for each validated block. This evaluation leads us qualifying the miners that have hopped along with their hopping behavior and financial performance.
Maria Apostolaki, Gian Marti, Jan Müller, Laurent Vanbever
Routing attacks remain practically effective in the Internet today as existing countermeasures either fail to provide protection guarantees or are not easily deployable. Blockchain systems are particularly vulnerable to such attacks as they rely on Internet-wide communication to reach consensus. In particular, Bitcoin -the most widely-used cryptocurrency- can be split in half by any AS-level adversary using BGP hijacking. In this paper, we present SABRE, a secure and scalable Bitcoin relay network which relays blocks worldwide through a set of connections that are resilient to routing attacks. SABRE runs alongside the existing peer-to-peer network and is easily deployable. As a critical system, SABRE design is highly resilient and can efficiently handle high bandwidth loads, including Denial of Service attacks. We built SABRE around two key technical insights. First, we leverage fundamental properties of inter-domain routing (BGP) policies to host relay nodes: (i) in locations that are inherently protected against routing attacks; and (ii) on paths that are economically preferred by the majority of Bitcoin clients. These properties are generic and can be used to protect other Blockchain-based systems. Second, we leverage the fact that relaying blocks is communication-heavy, not computation-heavy. This enables us to offload most of the relay operations to programmable network hardware (using the P4 programming language). Thanks to this hardware/software co-design, SABRE nodes operate seamlessly under high load while mitigating the effects of malicious clients. We present a complete implementation of SABRE together with an extensive evaluation. Our results demonstrate that SABRE is effective at securing Bitcoin against routing attacks, even with deployments as small as 6 nodes.
Stefano Angieri, Alberto García-Martínez, Bingyang Liu, Zhiwei Yan · 6 authors
The current system to manage the global pool of IP addresses is centralized\nin five transnational organizations, the Regional Internet Registries (RIRs).\nEach of these RIRs manage the address pool for a large number of countries.\nBecause the RIRs are private organizations, they are subject to the legal\nframework of the country where they are based. This configuration results in a\njurisdictional overflow from the legal framework of the countries where the RIR\nis based to all the countries that the RIRs are serving (the countries served\nby the RIRs de facto become subjects of the legal system of the country where\nthe RIR is hosted). The situation is aggravated by the deployment of new\nsecurity techniques such as the RPKI and BGPsec, that enable enforcement of\nallocations by the RIRs. In this paper we present InBlock, a blockchain-based\ndistributed governance body aimed to provide de-centralized management of IP\naddresses. InBlock also aims to fulfil the same objectives as the current IP\naddress allocation system, namely, uniqueness, fairness, conservation,\naggregation, registration and minimized overhead. InBlock is implemented as a\nDecentralized Autonomous Organization, i.e., as a set of blockchain's smart\ncontracts in Ethereum. Any entity may request an allocation of addresses to the\nInBlock registry by solely performing a (crypto)currency transfer to the\nInBlock. The fee required, along with the annual renewal fee, serves as a\nmechanism to deter stockpiling and other wasteful practices. As with any novel\ntechnology, there are many open questions about the usage of blockchains to\nbuild an IP address registry. For this reason, we believe that practical\nexperimentation is required in order to have hands-on experiences about such a\nsystem. We propose to conduct an experiment on distributed address management\nusing InBlock as a starting point to inform future directions in this area.\n
While the smart surveillance system enhanced by the Internet of Things (IoT) technology becomes an essential part of Smart Cities, it also brings new concerns in security of the data. Compared to the traditional surveillance systems that is built following a monolithic architecture to carry out lower level operations, such as monitoring and recording, the modern surveillance systems are expected to support more scalable and decentralized solutions for advanced video stream analysis at the large volumes of distributed edge devices. In addition, the centralized architecture of the conventional surveillance systems is vulnerable to single point of failure and privacy breach owning to the lack of protection to the surveillance feed. This position paper introduces a novel secure smart surveillance system based on microservices architecture and blockchain technology. Encapsulating the video analysis algorithms as various independent microservices not only isolates the video feed from different sectors, but also improve the system availability and robustness by decentralizing the operations. The blockchain technology securely synchronizes the video analysis databases among microservices across surveillance domains, and provides tamper proof of data in the trustless network environment. Smart contract enabled access authorization strategy prevents any unauthorized user from accessing the microservices and offers a scalable, decentralized and fine-grained access control solution for smart surveillance systems.
Blockchain-enabled e-voting (BEV) could reduce voter fraud and increase voter access. Eligible voters cast a ballot anonymously using a computer or smartphone. BEV uses an encrypted key and tamper-proof personal IDs. This article highlights some BEV implementations and the approach’s potential benefits and challenges.
Tooba Faisal, Nicolas T. Courtois, Antoaneta Serguieva
The use of blockchains is growing every day, and their utility has greatly expanded from sending and receiving crypto-coins to smart-contracts and decentralized autonomous organizations. Modern blockchains underpin a variety of applications: from designing a global identity to improving satellite connectivity. In our research we look at the ability of blockchains to store metadata in an increasing volume of transactions and with evolving focus of utilization. We further show that basic approaches to improving blockchain privacy also rely on embedding metadata. This paper identifies and classifies real-life blockchain transactions embedding metadata of a number of major protocols running essentially over the bitcoin blockchain. The empirical analysis here presents the evolution of metadata utilization in the recent years, and the discussion suggests steps towards preventing criminal use. Metadata are relevant to any blockchain, and our analysis considers primarily bitcoin as a case study. The paper concludes that simultaneously with both expanding legitimate utilization of embedded metadata and expanding blockchain functionality, the applied research on improving anonymity and security must also attempt to protect against blockchain abuse.
Open access
2 source records
cs.CR
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
By comparing cryptocurrencies with other existing payment methods, including banknotes and bank cards, it is clear that the use of Bitcoin and its competitors (Ethereum, \dots) is almost insignificant in world trade. We may also note that these cryptocurrencies have become tools of speculation, which is the antithesis of their primary purpose. Based essentially on the security of electronic signatures, the Ecash introduced here will put the users back to the center of the game and exclude miners and their enormous waste of power energy. Thus, the purpose of this paper is to show that even a piece of paper can be recycled into a secure Ecash, while remaining environmentally friendly. Hence, we create here a cryptocurrency that would use a slight modification of the current banknotes to set up anonymous electronic transactions. By trading with banknotes, we mechanically transfer ownership of the paper money from one owner to another, hence, in this scheme, we introduce the notion of ownership transfer. It implies that at each transaction the elements allowing to authenticate the Ecash does not change, while the ownership certificate will change since the Ecash is transfer towards someone else.
Recent work has demonstrated significant anonymity vulnerabilities in\nBitcoin's networking stack. In particular, the current mechanism for\nbroadcasting Bitcoin transactions allows third-party observers to link\ntransactions to the IP addresses that originated them. This lays the groundwork\nfor low-cost, large-scale deanonymization attacks. In this work, we present\nDandelion++, a first-principles defense against large-scale deanonymization\nattacks with near-optimal information-theoretic guarantees. Dandelion++ builds\nupon a recent proposal called Dandelion that exhibited similar goals. However,\nin this paper, we highlight simplifying assumptions made in Dandelion, and show\nhow they can lead to serious deanonymization attacks when violated. In\ncontrast, Dandelion++ defends against stronger adversaries that are allowed to\ndisobey protocol. Dandelion++ is lightweight, scalable, and completely\ninteroperable with the existing Bitcoin network. We evaluate it through\nexperiments on Bitcoin's mainnet (i.e., the live Bitcoin network) to\ndemonstrate its interoperability and low broadcast latency overhead.\n
James Tapsell, Raja Naeem Akram, Konstantinos Markantonakis
Bitcoin is a decentralised digital currency that relies on cryptography rather than trusted third parties such as central banks for its security. Underpinning the operation of the currency is a peer-to-peer (P2P) network that facilitates the execution of transactions by end users, as well as the transaction confirmation process known as bitcoin mining. The security of this P2P network is vital for the currency to function and subversion of the underlying network can lead to attacks on bitcoin users including theft of bitcoins, manipulation of the mining process and denial of service (DoS). As part of this paper the network protocol and bitcoin core software are analysed, with three bitcoin message exchanges (the connection handshake, GETHEADERS/HEADERS and MEMPOOL/INV) found to be potentially vulnerable to spoofing and use in distributed denial of service (DDoS) attacks. Possible solutions to the identified weaknesses and vulnerabilities are evaluated, such as the introduction of random nonces into network messages exchanges.
Freya Sheer Hardwick, Apostolos Gioulis, Raja Naeem Akram, Konstantinos Markantonakis
Technology has positive impacts on many aspects of our social life. Designing a 24hour globally connected architecture enables ease of access to a variety of resources and services. Furthermore, technology like Internet has been a fertile ground for innovation and creativity. One of such disruptive innovation is blockchain -- a keystone of cryptocurrencies. The blockchain technology is presented as a game changer for many of the existing and emerging technologies/services. With its immutability property and decentralised architecture, it is taking centre stage in many services as an equalisation factor to the current parity between consumers and large corporations/governments. One of such potential applications of the blockchain is in e-voting schemes. The objective of such a scheme would be to provide a decentralised architecture to run and support a voting scheme that is open, fair and independently verifiable. In this paper, we propose potentially a new e-voting protocol that utilises the blockchain as a transparent ballot box. The protocol has been designed with adhering to the fundamental e-voting properties in mind as well as offering a degree of decentralisation and allowing for the voter to change/update their vote (within the permissible voting period). The paper highlights the pros and cons of using blockchain for such a proposal from practical point view in both development/deployment and usage contexts. Concluding the paper with a potential roadmap for blockchain technology to be able to support complex applications.
Freya Sheer Hardwick, Raja Naeem Akram, Konstantinos Markantonakis
At a time when society is in constant transition to keep up with technological advancement, we are seeing traditional paradigms being increasingly challenged. The fundamentals of governance are one such paradigm. As society's values have shifted, so have expectations of government shifted from the traditional model to something commonly referred to as `open governance'. Though a disputed term, we take open governance to mean a concept, which encourages and facilitates openness, accountability, and responsiveness to citizens. For the success of open governance initiatives, there are some technologies, such as the internet, that are crucial. These technologies enable access to both the data and to engagement activities between citizens and government. There are also other technologies, like blockchain and smart contacts, which could be utilised to assist open governance. A sound starting point would be moving from a system where information is tediously released by a government, on an `as they please' basis, to an infrastructure where critical actions are captured with strong integrity, non-repudiation and evidential guarantees. With an added dimension that facilitates these actions record be accessible to public scrutiny in near real-time. One candidate technology for capturing such actions is blockchain. Initially, blockchains were mainly used to facilitate cryptocurrencies as a record of transactions. The notable example being bitcoin. However, in recent years, blockchains utility is being recognised through smart contracts - potentially a vital building block to realising open and transparent government activities. In this paper, we employ the concept of smart contracts to government tendering activities. The proposed scheme is based on smart contracts, enabling a fair, transparent and independently verifiable (auditable) government tendering scheme. The scheme is then implemented on the Ethereum platform to evaluate the performance and financial cost implications, along with an evaluation of the potential security and auditability challenges.
We present IPchain, a blockchain to store the allocations and delegations of IP addresses, with the aim of easing the deployment of secure interdomain routing systems. Interdomain routing security is of vital importance to the Internet since it prevents unwanted traffic redirections. IPchain makes use of blockchains' properties to provide flexible trust models and simplified management when compared to existing systems. In this paper we argue that Proof of Stake is a suitable consensus algorithm for IPchain due to the unique incentive structure of this use-case. We have implemented and evaluated IPchain's performance and scalability storing around 150k IP prefixes in a 1GB chain.
George Kappos, Haaroon Yousaf, Mary Maller, Sarah Meiklejohn
Among the now numerous alternative cryptocurrencies derived from Bitcoin, Zcash is often touted as the one with the strongest anonymity guarantees, due to its basis in well-regarded cryptographic research. In this paper, we examine the extent to which anonymity is achieved in the deployed version of Zcash. We investigate all facets of anonymity in Zcash's transactions, ranging from its transparent transactions to the interactions with and within its main privacy feature, a shielded pool that acts as the anonymity set for users wishing to spend coins privately. We conclude that while it is possible to use Zcash in a private way, it is also possible to shrink its anonymity set considerably by developing simple heuristics based on identifiable patterns of usage.
The use of technology has become important at this point in helping to meet human needs.Due to the increasing use of technology, new challenges are brought in the process of democracy as most people today don’t trust their governments, making elections is very important in modern democracy . Elections have a great importance in determining who will rule a nation or an organization or it can be said as it is an event that decides the fate of any nation. In modern democracy, elections are very important but large sections of society around the world do not trust their election system which is a major concern for democracy. Even the world’s largest democracies like India, United States, still suffer from a flawed electoral system. Vote rigging, hacking of EVM (Electronic voting machine), election manipulation, and polling booth capturing are the major issues in the current voting system The blockchain is said as emerging, decentralized, and distributed technology that promises to enhance different aspects of many industries. Expanding e-voting into blockchain technology could be the solution to eliminate the present concerns in e-voting system There is no doubt that the ever changing concept of the blockchain, which is the backbone of the famous cryptocurrency Bitcoin has triggered the start of a new era in the Internet and the online services. While most people focus only on bitcoin and other cryptocurrencies; there are in fact, many operations, both administrative and fintech that can only be done online/offline can now safely be moved to the Internet as online services because of immutability of blockchain. What makes blockchain a powerful tool is its smarts contracts and many features which overcomes traditional systems. Smart contracts are meaningful pieces of codes, to be integrated in the blockchain and executed as scheduled in every step of blockchain updates. E-votin, is another trending, yet critical, topic related to the online services. The blockchain with the smart contracts, emerges as a good candidate to use in developments of safer, cheaper, more secure, more transparent, and easier-to-use e-voting systems.Due to its consistency, widespread use, and provision of smart contracts logic, Ethereum and its network is one of the most suitable ones. An e-voting system must be secure, as it should not allow duplicated votes and be fully transparent, while protecting the privacy of the attendees. In this project, we have implemented and tested an e-voting application as a smart contract for the Ethereum network using the Ethereum and the Solidity language.
Immigrants usually are pro-social towards their hometowns and try to improve them. However, the lack of trust in their government can drive immigrants to work individually. As a result, their pro-social activities are usually limited in impact and scope. This paper studies the interface factors that ease collaborations between immigrants and their home governments. We specifically focus on Mexican immigrants in the US who want to improve their rural communities. We identify that for Mexican immigrants having clear workflows of how their money flows and a sense of control over this workflow is important for collaborating with their government. Based on these findings, we create a blockchain based system for building trust between governments and immigrants. We finish by discussing design implications of our work and future directions.
A trusted electronic election system requires that all the involved information must go public, that is, it focuses not only on transparency but also privacy issues. In other words, each ballot should be counted anonymously, correctly, and efficiently. In this work, a lightweight E-voting system is proposed for voters to minimize their trust in the authority or government. We ensure the transparency of election by putting all message on the Ethereum blockchain, in the meantime, the privacy of individual voter is protected via an efficient and effective ring signature mechanism. Besides, the attractive self-tallying feature is also built in our system, which guarantees that everyone who can access the blockchain network is able to tally the result on his own, no third party is required after voting phase. More importantly, we ensure the correctness of voting results and keep the Ethereum gas cost of individual participant as low as possible, at the same time. Clearly, the pre-described characteristics make our system more suitable for large-scale election.