Ui-Jun Baek, Se-Hyun Ji, Jee- Tae Park, Min‐Seob Lee · 6 authors
Since the inception of Bitcoin, the first cryptocurrency to implement blockchain technology, the cryptocurrency market has experienced significant growth.However, this growth has also brought about numerous vulnerabilities and attacks that pose a threat to the Bitcoin ecosystem.These attacks are not only focused on the Bitcoin network itself but also extend to the services that utilize it.Recent surveys have indicated the need to analyze and identify Distributed Denial of Service (DDoS) attacks, considering the interconnectedness between network-level data and service-level DDoS attacks within the Bitcoin system.Typically, the Bitcoin network is considered resilient against DDoS attacks due to the decentralized nature of its ledger.Nevertheless, there are potential vulnerabilities that could be exploited, such as message spoofing using the Transmission Control Protocol (TCP).Additionally, DDoS attacks often target services associated with Bitcoin usage rather than directly impacting the network's performance or stealing currency.Although these service-level attacks may not have an immediate impact, they can ultimately undermine the value of Bitcoin, leading to depreciation.The majority of DDoS attacks on Bitcoin-related services occur on exchanges and mining pools.Our approach involves evaluating experimental outcomes based on proposed metrics to establish a correlation between network-level data and service-level DDoS attacks in the Bitcoin system.By doing so, we aim to detect and analyze these attacks, thereby identifying potential associations.Furthermore, we posit that the methodology employed in this study could be applicable to other blockchain systems, extending its usefulness beyond the Bitcoin network.
Ankit Gangwal, Samuele Giuliano Piazzetta, Gianluca Lain, Mauro Conti
Cybercriminals have been exploiting cryptocurrencies to commit various unique financial frauds. Covert cryptomining - which is defined as an unauthorized harnessing of victims' computational resources to mine cryptocurrencies - is one of the prevalent ways nowadays used by cybercriminals to earn financial benefits. Such exploitation of resources causes financial losses to the victims. In this paper, we present our novel and efficient approach to detect covert cryptomining. Our solution is a generic solution that, unlike currently available solutions to detect covert cryptomining, is not tailored to a specific cryptocurrency or a particular form of cryptomining. In particular, we focus on the core mining algorithms and utilize Hardware Performance Counters (HPC) to create clean signatures that grasp the execution pattern of these algorithms on a processor. We built a complete implementation of our solution employing advanced machine learning techniques. We evaluated our methodology on two different processors through an exhaustive set of experiments. In our experiments, we considered all the cryptocurrencies mined by the top-10 mining pools, which collectively represent the largest share (84% during Q3 2018) of the cryptomining market. Our results show that our classifier can achieve a near-perfect classification with samples of length as low as five seconds. Due to its robust and practical design, our solution can even adapt to zero-day cryptocurrencies. Finally, we believe our solution is scalable and can be deployed to tackle the uprising problem of covert cryptomining.
Democratic principles demand that every voter should be able to individually verify that their vote is recorded as intended and counted as recorded, without having to trust any authorities. However, most end-to-end (E2E) verifiable voting protocols that provide universal verifiability and voter secrecy implicitly require to trust some authorities or auditors for the correctness guarantees that they provide.
In this paper, we explore the notion of individual verifiability. We evaluate the existing E2E voting protocols and propose a new protocol that guarantees such verifiability without any trust requirements. Our construction depends on a novel vote commitment scheme to capture voter intent that allows voters to obtain a direct zero-knowledge proof of their vote being recorded as intended. We also ensure protection against spurious vote injection or deletion post eligibility verification, and polling-booth level community profiling.
Driven by the increasing number of stationary and portable devices, Distributed Denial-of-Service (DDoS) attacks pose a major threat to Internet availability. While advantages of cooperative defenses have been widely recognized over traditional on-premise defenses, there is not a widespread deployment of such cooperative defenses. This work demonstrates the Blockchain Signaling System (BloSS), a modular, network-agnostic and cooperative DDoS defense system consisting of independent instances working together to mitigate attacks targeted at any member of this alliance.
Stefano Angieri, Alberto García-Martínez, Bingyang Liu, Zhiwei Yan · 6 authors
The current system to manage the global pool of IP addresses is centralized in five transnational organizations, known as regional internet registries (RIRs). Each of them manages the address pool for many countries. In this paper, we present InBlock, a distributed autonomous organization that provides the decentralized management of IP addresses. The InBlock also fulfills the same objectives as those fulfilled by the current IP address allocation organizations, i.e., uniqueness, fairness, conservation, aggregation, registration, and minimized overhead. The InBlock is implemented as a set of blockchain's smart contracts in Ethereum, and it implements all the functions needed for the management of a global pool of addresses without any human intervention. Any entity may request an allocation of addresses to the InBlock registry by performing a (crypto)currency transfer to the InBlock. The fee required, along with the annual renewal fee, serves as a mechanism to deter stockpiling and other wasteful practices. As with any novel technology, there are many open questions about the usage of blockchains to build an IP address registry. For this reason, we believe that practical experimentation is required in order to have hands-on experience, so we propose to conduct an experiment on the InBlock as a starting point to inform about the future directions in this space.
Stefano Bistarelli, Ivan Mercanti, Francesco Santini
In Bitcoin, the most common kind of transactions is in the form “Bob pays Alice”, and it is based on the Pay to-Public Key Hash(P2PKH) script, which are resolved by sending the public key and a digital signature created by the corresponding private key. P2PKH transactions are just one among many standard classes: a transaction is standard if it passes Bitcoin Core’s IsStandard() and IsStandardTx() tests. However, the creation of ad-hoc scripts to lock (and unlock) transactions allows for also generating non-standard transactions, which can be nevertheless broadcast and mined as well. In this work, we explore the Bitcoin block-chain with the purpose to analyze and classify standard and non-standard transactions, understanding how much the standard behaviour is respected.
Aug 1, 2019·2019 IEEE Intl Conf on Dependable, Autonomic and Secure Computing, Intl Conf on Pervasive Intelligence and Computing, Intl Conf on Cloud and Big Data Computing, Intl Conf on Cyber Science and Technology Congress (DASC/PiCom/CBDCom/CyberSciTech)
Software defined networking (SDN) is one of the most popular network technologies which provides an adaptive, agile and flexible network management and visibility. Although SDN architecture provides manifold benefits but on the same time its dependence on a logically centralized controller lead to the single point of failure. An attacker can easily capture the any forwarding device and restrict the availability of the controller using different prevalent attacks. Distributed denial of service (DDoS) is one of the most popular attack of this category which is quiet prevalent in SDN. Here, the aim of the attackers is to inject false script in the open flow tables through malicious switches which multiply exponentially. Therefore, in this paper, a blockchain as a service framework has been presented wherein BlockSDSec model is designed to provide security as a separate service for the SDN architecture. This work provides a mechanism to prevent the threats of DDoS at the switch level by embedding an security using blockchain onto the interaction channels of data and control planes. The load balancing at the controller level is achieved using a virtual controller. The proposed scheme is simulated using MiniNet Emulator to analyze the delay originating from usage of blockchain.
Internet of Things (IoT) is growing at an exponential rate but the area of privacy and security in IoT still remains unexplored. The existing algorithms or methods are mainly centralized and hence they are vulnerable due to their single point authentication topology. As it has been estimated that by 2020 there will be more ‘things’ than people on this earth the problem of security becomes a major concern in IoT networks, as a person having control to an IoT network will be able to control a large portion of an organization. Blockchain has recently been used to provide security to peer-to-peer networks. Blockchains are computationally expensive, heavyweight and are considered unsuitable for IoT architecture. In this paper a new lightweight and secure architecture for IoT by using Ethereum Blockchain retaining most of its security providing powers is proposed. Since Blockchain is decentralized it solves the single point authentication problem existing in IoT networks. A Smart Home System as a representative case study has been implemented for broader IoT applications. The two parameters measured are temperature and intrusion detection. The proposed model tackles some more challenges that exist in IoT networks. The Qualitative evaluation of the proposed architecture highlights how it tackles various attacks.
Bitcoin denkler arası/eşitler arası ağa dayalı olan kripto bir birimidir. Bitcoinin en temel özelliği herhangi bir otorite tarafından arz ve garanti edilmemesidir. Bitcoin işlemleri, bunları dijital bir deftere kaydeden blok zinciri ile bütün kullanıcılar için umumi hâle gelir. Bitcoin ağının merkezî olmayan yapısı, cebri icra süreci bakımından bazı sorunları da beraberinde getirmektedir. Bir taraf akdi bir ilişkiye istinaden belirli bir tutar bitcoini ifa etmeyi taahhüt ederse, diğer taraf kararlaştırılan bitcoini almak için cebri icra takibi başlatabilmelidir. Diğer taraftan, bir icra dairesi, takip alacaklısının talebi üzerine, bir bitcoin kullanıcısının para borcundan ötürü bitcoinini haczedebilmelidir. Haciz işleminde bitcoinin merkezî olmayan yapısı dikkate alınmalıdır.
Blockchain sistemi blokların birbirine zincir gibi bağlandığı bir dağıtık veri tabanıdır. Bu sistemde merkezi bir sunucu bulunmamaktadır. Sistemdeki işlemler eşler arası aracısız bir şekilde gerçekleşmektedir. Blockchain’in işlevleri arasında kripto paraların işleyişi de bulunmaktadır. Kripto para kavramı Bitcoin, Altcoin ve Token’ları kapsamaktadır. Blockchain temelinde işleyen Bitcoin ilk ve en popüler kripto para konumundadır.   Şu an için dünya genelinde binin üzerinde kripto para bulunmaktadır. Bunların toplam piyasa değeri şu an için 320 milyar dolar civarındadır. Kripto paraların ticaret şirketlerine getirilmesiyle etkin bir şekilde ekonomi çarkının içine dâhil edilmesi oldukça önem arz etmektedir. Çalışmamızda Bitcoin’in ticaret şirketlerine sermaye olarak getirilip getirilemeyeceği tespit edildikten sonra bunların sermaye niteliğine ve ticaret şirketlerine sermaye olarak konulması usulüne değinilecektir. 
Due to little attention given to anonymous protection against eavesdropping attacks in Bitcoin network, this paper initiatively proposes a solution to Bitcoin anonymization based on network structure. We first present a general adversarial network model for formulizing deanonymization attack, then present a novel propagation method APRP(Adaptive PageRank Propagation) that adopts PageRank as propagation delay factor and constantly adjusts PR-value of nodes to adapt to network dynamics. Experiments on both simulated and real Bitcoin networks confirm the superiority of APRP in terms of 20-50% performance enhancement under various deanonymization attacks.
Open access
Internet Traffic Analysis and Secure E-voting
Privacy-Preserving Technologies in Data
Advanced Steganography and Watermarking Techniques
In this paper, we propose a system for mixing transactions in payment networks such as credit networks. Credit networks like Ripple and Stellar are increasingly popular, and can facilitate crosscurrency transactions in a fraction of the time it would take for banks or other financial institutions to process the same transaction, and at a fraction of the cost. Unlike for cryptocurrencies, there has been little work in the area of designing secure and private mixers for credit networks. Mixers for cryptocurrencies such as Bitcoin cannot be directly applied to the credit network domain because credit networks have an inherently different structure and purpose than cryptocurrencies. We design a system that uses cryptographic constructs such as ring signatures, commitments, and zero knowledge proofs to provide security/integrity of all transactions, ensures privacy of the users involved in a transaction, as well as privacy of the amount transacted. We also provide preliminary experimental results.
In this paper, we consider a scenario where a bitcoin liquidity provider sells bitcoins to clients. When a client pays for a bitcoin online, the provider is able to link the client's payment information to the bitcoin sold to that client. To address the privacy concerns of clients, we require that the bitcoin provider cannot tell the relationship between the real identities of clients and the sold bitcoins in the blockchain. This requirement can be effectively achieved by using blind signatures. However, existing blind signature schemes are incompatible with the Elliptic Curve Digital Signature Algorithm (ECDSA) which is used by most of the existing bitcoin protocol, thus cannot be applied directly in Bitcoin. In this paper, we propose a new blind signature scheme that allows generating a blind signature compatible with the standard ECDSA. Afterwards, we make use of the new scheme to achieve bitcoin transaction anonymity. The new scheme is built on a variant of the Paillier cryptosystem and its homomorphic properties. As long as the modified Paillier cryptosystem is semantically secure, the new blind signature scheme has blindness and unforgeability.
Open access
Blockchain Technology Applications and Security
Internet Traffic Analysis and Secure E-voting
Advanced Steganography and Watermarking Techniques
Samvid Dharanikota, Michael Jensen, Sebastian Rom Kristensen, Mathias Sass Michno · 7 authors
Randomness beacons are services that periodically emit a random number, allowing users to base decisions on the same random value without trusting anyone: ideally, the randomness beacon does not only produce unpredictable values, but is also of low computational complexity for the users, bias-resistant and publicly verifiable. Such randomness beacons can serve as an important primitive for smart contracts in a variety of contexts. This paper first presents a structured security analysis, based on which we then design, implement, and evaluate a trustworthy and efficient randomness beacon. Our approach does not require users to register or run any computationally intensive operations. We then compare different implementation and deployment options on distributed ledgers, and report on an Ethereum smart contract-based lottery using our beacon.
Jordi Zayuelas i Munoz, José Suárez‐Varela, Pere Barlet‐Ros
In the last few years, cryptocurrency mining has become more and more important on the Internet activity and nowadays is even having a noticeable impact on the global economy. This has motivated the emergence of a new malicious activity called cryptojacking, which consists of compromising other machines connected to the Internet and leverage their resources to mine cryptocurrencies. In this context, it is of particular interest for network administrators to detect possible cryptocurrency miners using network resources without permission. Currently, it is possible to detect them using IP address lists from known mining pools, processing information from DNS traffic, or directly performing Deep Packet Inspection (DPI) over all the traffic. However, all these methods are still ineffective to detect miners using unknown mining servers or result too expensive to be deployed in real-world networks with large traffic volume. In this paper, we present a machine learning-based method able to detect cryptocurrency miners using NetFlow/IPFIX network measurements. Our method does not require to inspect the packets' payload; as a result, it achieves cost-efficient miner detection with similar accuracy than DPI-based techniques.
Federated identity management enables users to access multiple systems using\na single login credential. However, to achieve this a complex privacy\ncompromising authentication has to occur between the user, relying party (RP)\n(e.g., a business), and a credential service provider (CSP) that performs the\nauthentication. In this work, we use a smart contract on a blockchain to enable\nan architecture where authentication no longer involves the CSP. Authentication\nis performed solely through user to RP communications (eliminating fees and\nenhancing privacy). No third party needs to be contacted, not even the smart\ncontract. No public key infrastructure (PKI) needs to be maintained. And no\nrevocation lists need to be checked. In contrast to competing smart contract\napproaches, ours is hierarchically managed (like a PKI) enabling better\nvalidation of attribute providers and making it more useful for large entities\nto provide identity services for their constituents (e.g., a government) while\nstill enabling users to maintain a level of self-sovereignty.\n
In the past few years in many countries people have experienced the erosion of trust in the main pillars of democracy, the voting and election systems. Many authors envisage the blockchain technology as a tool for restoration of trust (Tapscott 2016; Swislow 2016; Shin 2016). Our research is aimed at the potential use of blockchain technology in social systems for enhancing trust and increasing participation. We aim to explore whether the blockchain technology is suitable for voting or elections in large communities and the issues to be addressed for real world applications to leverage democratic rights. Our final conclusion is that there are both theoretical and practical obstacles in the way of such direct applications.
Adriano Di Luzio, Danilo Francati, Giuseppe Ateniese
This work presents Arcula, a new design for hierarchical deterministic wallets that brings identity-based addresses to the blockchain. Arcula is built on top of provably secure cryptographic primitives. It generates all its cryptographic secrets from a user-provided seed and enables the derivation of new public keys based on the identities of users, without requiring any secret information. Unlike other wallets, it achieves all these properties while being secure against privilege escalation. We formalize the security model of hierarchical deterministic wallets and prove that an attacker compromising an arbitrary number of users within an Arcula wallet cannot escalate his privileges and compromise users higher in the access hierarchy. Our design works out-of-the-box with any blockchain that enables the verification of signatures on arbitrary messages. We evaluate its usage in a real-world scenario on the Bitcoin Cash network.
Francisco J. Marmolejo-Cossío, Eric Brigham, Benjamin Sela, Jonathan Katz
The Bitcoin protocol prescribes certain behavior by the miners who are responsible for maintaining and extending the underlying blockchain; in particular, miners who successfully solve a puzzle, and hence can extend the chain by a block, are supposed to release that block immediately. Eyal and Sirer showed, however, that a selfish miner is incentivized to deviate from the protocol and withhold its blocks under certain conditions. The analysis by Eyal and Sirer, as well as in followup work, considers a \emph{single} deviating miner (who may control a large fraction of the hashing power in the network) interacting with a remaining pool of honest miners. Here, we extend this analysis to the case where there are \emph{multiple} (non-colluding) selfish miners. We find that with multiple strategic miners, specific deviations from honest mining by multiple strategic agents can outperform honest mining, even if individually miners would not be incentivised to be dishonest. This previous point effectively renders the Bitcoin protocol to be less secure than previously thought.
Zhengbing Hu, Ivan Dychka, Mykola Onai, Yuri Zhykin
One of the most important problems of modern cryptocurrency networks is the problem of scaling: advanced cryptocurrencies like Bitcoin can handle around 5 transactions per second. One of the most promising solutions to this problem are second layer payment protocols: payment networks implemented on top of base cryptocurrency network layer, based on the idea of delaying publication of intermediate transactions and using base network only as a finalization layer. Such networks consist of entities that interact with the cryptocurrency system via a payment channel protocol, and can send, receive and forward payments. This paper describes a formal actor-based model of payment channel network and uses it to formulate a modified payment protocol that can be executed in the network without requiring any information about its topology and thus can hide information about financial relations between nodes.
Networks (Autonomous Systems-AS) allocate or revoke IP prefixes with the intervention of official Internet resource number authorities, and select and advertise policy-compliant paths towards these prefixes using the inter-domain routing system and its primary enabler, the Border Gateway Protocol (BGP). Securing BGP has been a long-term objective of several research and industrial efforts during the last decades, that have culminated in the Resource Public Key Infrastructure (RPKI) for the cryptographic verification of prefix-to-AS assignments. However, there is still no widely adopted solution for securing IP prefixes and the (AS-)paths leading to them; approaches such as BGPsec have seen minuscule deployment. In this work, we design and implement a Blockchain-based system that (i) can be used to validate both of these resource types, (ii) can work passively and does not require any changes in the inter-domain routing system (BGP, RPKI), and (iii) can be combined with currently available systems for the detection and mitigation of routing attacks. We present early results and insights w.r.t. scalability.
Software Defined Networking (SDN) technology increases the evolution of Internet and network development. SDN, with its logical centralization of controllers and global network overview changes the network's characteristics, on term of flexibility, availability and programmability. However, this development increased the network communication security challenges. To enhance the SDN security, we propose the BCFR solution to avoid false flow rules injection in SDN data layer devices. In this solution, we use the blockchain technology to provide the controller authentication and the integrity of the traffic flow circulated between the controller and the other network elements. This work is implemented using OpenStack platform and Onos controller. The evaluation results show the effectiveness of our proposal.
Kaihua Qin, Hadass, Henryk, Arthur Gervais, Joel Reardon
Lightweight Bitcoin clients execute a Simple Payment Verification (SPV) protocol to verify the validity of transactions related to a particular user. Currently, lightweight clients \nuse Bloom filters to significantly reduce the amount of bandwidth \nrequired to validate a particular transaction. This is despite the \nfact that research has shown that Bloom filters are insufficient \nat preserving the privacy of clients’ queries. \nIn this paper we describe our design of an SPV protocol \nthat leverages Private Information Retrieval (PIR) to create fully \nprivate and performant queries. We show that our protocol has \na low bandwidth and latency cost; properties that make our \nprotocol a viable alternative for lightweight Bitcoin clients and \nother cryptocurrencies with a similar SPV model. In contract \nto Bloom filters, our PIR-based approach offers deterministic \nprivacy to the user. \nAmong our results, we show that in the worst case, clients who \nwould like to verify 100 transactions occurring in the past week \nincurs a bandwidth cost of 33.54 MB with an associated latency \nof approximately 4.8 minutes, when using our protocol. The \nsame query executed using the Bloom-filter-based SPV protocol \nincurs a bandwidth cost of 12.85 MB; this is a modest overhead \nconsidering the privacy guarantees it provides.
Bitcoin, introduced in 2008 and launched in 2009, is the first digital currency to solve the double spending problem without relying on a trusted third party. Bitcoin provides a way to transact without any trusted intermediary, but its privacy guarantees are questionable. Despite the fact that Bitcoin addresses are not linked to any identity, multiple deanonymization attacks have been proposed. Alternative cryptocurrencies such as Dash, Monero, and Zcash aim to provide stronger privacy by using sophisticated cryptographic techniques to obfuscate transaction data. Previous work in cryptocurrency privacy mostly focused on applying data mining algorithms to the transaction graph extracted from the blockchain. We focus on a less well researched vector for privacy attacks: network analysis. We argue that timings of transaction messages leak information about their origin, which can be exploited by a well connected adversarial node. For the first time, network level attacks on Bitcoin and the three major privacy-focused cryptocurrencies have been examined. We describe the message propagation mechanics and privacy guarantees in Bitcoin, Dash, Monero, and Zcash. We propose a novel technique for linking transactions based on transaction propagation analysis. We also unpack address advertisement messages (ADDR), which under certain assumptions may help in linking transaction clusters to IP addresses of nodes. We implement and evaluate our method, deanonymizing our own transactions in Bitcoin and Zcash with a high level of accuracy. We also show that our technique is applicable to Dash and Monero. We estimate the cost of a full-scale attack on the Bitcoin mainnet at hundreds of US dollars, feasible even for a low budget adversary.