Among the many cryptocurrencies, the most popular is bitcoin. It is a direct electronic system that deals with money and lets us make payments over network. To verify bitcoin transactions involving payments between users, we need to mine the data involved in these transactions. Data mining keeps a record of the various payments made and the services used in an organized form. Since mining is the bedrock of bitcoin framework, it is very important to make sure that the mined data is unalterable and complete by repeatedly verifying and adding new transactions. For this purpose, we use various algorithms and protocols, along with satisfying proof-of-stake and proof-of-work. These algorithms are studied and compared, and it is proposed that we could switch to proof-of-stake for bitcoin to make it more energy efficient as well as cost effective.
Mohsin Ur Rahman, Fabrizio Baiardi, Barbara Guidi, Laura Ricci
Decentralized Online Social Networks (DOSNs) have been proposed as an alternative solution to the current centralized Online Social Networks (OSNs). Online Social Networks are based on centralized architecture (e.g., Facebook, Twitter, or Google+), while DOSNs do not have a service provider that acts as central authority and users have more control over their information. Several DOSNs have been proposed during the last years. However, the decentralization of the OSN requires efficient solutions for protecting the privacy of users, and to evaluate the trust between users. Blockchain represents a disruptive technology which has been applied to several fields, among these also to Social Networks. In this paper, we propose a manageable, user-driven and auditable access control framework for DOSNs using blockchain technology. In the proposed approach, the blockchain is used as a support for the definition of privacy policies. The resource owner uses the public key of the subject to define flexible role-based access control policies, while the private key associated with the subject's Ethereum account is used to decrypt the private data once access permission is validated on the blockchain. We evaluate our solution by exploiting the Rinkeby Ethereum testnet to deploy the smart contract, and to evaluate its performance. Experimental results show the feasibility of the proposed scheme in achieving auditable and user-driven access control via smart contract deployed on the Blockchain.
Ze Wang, Jingqiang Lin, Quanwei Cai, Qiongxiao Wang · 6 authors
Traditional X.509 public key infrastructures (PKIs) depend on trusted certification authorities (CAs) to sign certificates, used in SSL/TLS to authenticate web servers and establish secure channels. However, recent security incidents indicate that CAs may (be compromised to) sign fraudulent certificates. In this article, we propose blockchain-based certificate transparency (CT) and revocation transparency (RT) to balance the absolute authority of CAs. Our scheme is compatible with X.509 PKIs but significantly reinforces the security guarantees of a certificate. The CA-signed certificates and their revocation status information of an SSL/TLS web server are published by the subject (i.e., the web server) as a transaction in the global certificate blockchain. The certificate blockchain acts as append-only public logs to monitor CAs’ certificate signing and revocation operations, and an SSL/TLS web server is granted with the cooperative control on its certificates. A browser compares the certificate received in SSL/TLS negotiations with the ones in the public certificate blockchain, and accepts it only if it is published and not revoked. We implement the prototype system with Firefox and Nginx, and the experimental results show that it introduces reasonable overheads.
Zero-Knowledge Proof-of-Identity from trusted public certificates (e.g., national identity cards and/or ePassports; eSIM) is introduced here to permissionless blockchains in order to remove the inefficiencies of Sybil-resistant mechanisms such as Proof-of-Work (i.e., high energy and environmental costs) and Proof-of-Stake (i.e., capital hoarding and lower transaction volume). The proposed solution effectively limits the number of mining nodes a single individual would be able to run while keeping membership open to everyone, circumventing the impossibility of full decentralization and the blockchain scalability trilemma when instantiated on a blockchain with a consensus protocol based on the cryptographic random selection of nodes. Resistance to collusion is also considered. Solving one of the most pressing problems in blockchains, a zk-PoI cryptocurrency is proved to have the following advantageous properties: - an incentive-compatible protocol for the issuing of cryptocurrency rewards based on a unique Nash equilibrium - strict domination of mining over all other PoW/PoS cryptocurrencies, thus the zk-PoI cryptocurrency becoming the preferred choice by miners is proved to be a Nash equilibrium and the Evolutionarily Stable Strategy - PoW/PoS cryptocurrencies are condemned to pay the Price of Crypto-Anarchy, redeemed by the optimal efficiency of zk-PoI as it implements the social optimum - the circulation of a zk-PoI cryptocurrency Pareto dominates other PoW/PoS cryptocurrencies - the network effects arising from the social networks inherent to national identity cards and ePassports dominate PoW/PoS cryptocurrencies - the lower costs of its infrastructure imply the existence of a unique equilibrium where it dominates other forms of payment
The Federal Election Commission (FEC) is the regulating authority over the monies that U.S. citizens are allowed to give to political candidates and parties. However, preexisting loopholes in FEC regulation allow for contributions to be made in situations that do not require donors to disclose their identity, a term coined as “dark money”. The increase of dark money in campaign financing and the ability of political spending to influence voter perspectives and decisions puts the credibility of the political finance system at stake. Additionally, with the introduction of blockchain, decentralized autonomous organizations (DAOs) and smart contracts to political financing these technologies collectively can serve as a new vehicle for bad actors to use. In this paper, the effects of blockchain and smart contracts on political finance are examined through four use cases to demonstrate how these technologies can extend anonymous, foreign interference in political campaign financing and further cripple public trust in it.
Zakaria Abou El Houda, Abdelhakim Hafid, Lyes Khoukhi
With the exponential growth in the number of insecure devices, the impact of Distributed Denial-of-Service (DDoS) attacks is growing rapidly. Existing DDoS mitigation schemes are facing obstacles due to low flexibility, lack of resources, and high cost. The new emerging technologies, such as blockchain, introduce new opportunities for low-cost, efficient and flexible DDoS attacks mitigation across multiple domains. In this paper, we propose a blockchain-based approach, called Cochain-SC, which combines two levels of mitigation, intra-domain and inter-domain DDoS mitigation. For intra-domain, we propose an effective DDoS mitigation method in the context of software defined networks (SDN); it consists of three schemes: (1) Intra Entropy-based scheme (I-ES) to measure, using sFlow, the randomness of data inside the domain; (2) Intra Bayes-based scheme (I-BS) to classify, based on entropy values, illegitimate flows; and (3) Intra-domain Mitigation (I-DM) scheme to effectively mitigate illegitimate flows inside the domain. For inter-domain, we propose a collaborative DDoS mitigation scheme based on blockchain; it uses the concept of smart contracts (i.e., Ethereum's smart contracts) to facilitate the collaboration among SDN-based domains (i.e., Autonomous System: AS) to mitigate DDoS attacks. For this aim, we design a novel and secure scheme that allows multiple SDN-based domains to securely collaborate and transfer attack information in a decentralized manner. Combining intra- and inter-domain DDoS mitigation, Cochain-SC allows an efficient mitigation along the path of an ongoing attack and an effective mitigation near the origin of the attack. This allows reducing the enormous cost of forwarding packets, across multiple domains, which consist mostly of useless amplified attack traffic. To the best of our knowledge, Cochain-SC is the first scheme that proposes to deal with both intra-domain and inter-domain DDoS attacks mitigation combining SDN, blockchain and smart contract. The implementation of Cochain-SC is deployed on Ethereum official test network Ropsten. Moreover, we conducted extensive experiments to evaluate our proposed approach; the experimental results show that Cochain-SC achieves flexibility, efficiency, security, cost effectiveness, and high accuracy in detecting illegitimate flows, making it a promising approach to mitigate DDoS attacks.
The electronic voting has emerged over time as a replacement to the paper-based voting to reduce the redundancies and inconsistencies. The historical perspective presented in the last two decades suggests that it has not been so successful due to the security and privacy flaws observed over time. This paper suggests a framework by using effective hashing techniques to ensure the security of the data. The concept of block creation and block sealing is introduced in this paper. The introduction of a block sealing concept helps in making the blockchain adjustable to meet the need of the polling process. The use of consortium blockchain is suggested, which ensures that the blockchain is owned by a governing body (e.g., election commission), and no unauthorized access can be made from outside. The framework proposed in this paper discusses the effectiveness of the polling process, hashing algorithms' utility, block creation and sealing, data accumulation, and result declaration by using the adjustable blockchain method. This paper claims to apprehend the security and data management challenges in blockchain and provides an improved manifestation of the electronic voting process.
With the rise of artificial intelligence (AI) and deep learning techniques, fake digital contents have proliferated in recent years. Fake footage, images, audios, and videos (known as deepfakes) can be a scary and dangerous phenomenon and can have the potential of altering the truth and eroding trust by giving false reality. Proof of authenticity (PoA) of digital media is critical to help eradicate the epidemic of forged content. Current solutions lack the ability to provide history tracking and provenance of digital media. In this paper, we provide a solution and a general framework using Ethereum smart contracts to trace and track the provenance and history of digital content to its original source even if the digital content is copied multiple times. The smart contract utilizes the hashes of the interplanetary file system (IPFS) used to store digital content and its metadata. Our solution focuses on video content, but the solution framework provided in this paper is generic enough and can be applied to any other form of digital content. Our solution relies on the principle that if the content can be credibly traced to a trusted or reputable source, the content can then be real and authentic. The full code of the smart contract has been made publicly available at Github.
Open access
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
Smart home systems provide a safe, comfortable, and convenient living environment for users, whereby users enjoy featured home services supported by the data collected and generated by smart devices in smart home systems. However, existing smart devices lack sufficient protection in terms of data security and privacy, and challenging security and privacy issues inevitably emerge when using these data. This article aims to address these challenging issues by proposing a private blockchain-based access control (PBAC) scheme. PBAC involves employing a private blockchain to provide an unforgeable and auditable foundation for smart home systems, that can thwart illegal data access, and ensure the accuracy, integrity, and timeliness of access records. A detailed security analysis shows that PBAC could preserve data security against various attacks. In addition, we conduct a comprehensive performance evaluation to demonstrate that PBAC is feasible and efficient.
Ali Dorri, Clemence Roulin, Raja Jurdak, Salil S. Kanhere
Security is one of the fundamental challenges in the Internet of Things (IoT) due to the heterogeneity and resource constraints of the IoT devices. Device classification methods are employed to enhance the security of IoT by detecting unregistered devices or traffic patterns. In recent years, blockchain has received tremendous attention as a distributed trustless platform to enhance the security of IoT. Conventional device identification methods are not directly applicable in blockchain-based IoT as network layer packets are not stored in the blockchain. Moreover, the transactions are broadcast and thus have no destination IP address and contain a public key as the user identity, and are stored permanently in blockchain which can be read by any entity in the network. We show that device identification in blockchain introduces privacy risks as the malicious nodes can identify users' activity pattern by analyzing the temporal pattern of their transactions in the blockchain. We study the likelihood of classifying IoT devices by analyzing their information stored in the blockchain, which to the best of our knowledge, is the first work of its kind. We use a smart home as a representative IoT scenario. First, a blockchain is populated according to a real-world smart home traffic dataset. We then apply machine learning algorithms on the data stored in the blockchain to analyze the success rate of device classification, modeling both an informed and a blind attacker. Our results demonstrate success rates over 90\% in classifying devices. We propose three timestamp obfuscation methods, namely combining multiple packets into a single transaction, merging ledgers of multiple devices, and randomly delaying transactions, to reduce the success rate in classifying devices. The proposed timestamp obfuscation methods can reduce the classification success rates to as low as 20%.
Bitcoin relies on a peer-to-peer overlay network to broadcast transactions and blocks. From the viewpoint of network measurement, we would like to observe this topology so we can characterize its performance, fairness and robustness. However, this is difficult because Bitcoin is deliberately designed to hide its topology from onlookers. Knowledge of the topology is not in itself a vulnerability, although it could conceivably help an attacker performing targeted eclipse attacks or to deanonymize transaction senders. In this paper we present TxProbe, a novel technique for reconstructing the Bitcoin network topology. TxProbe makes use of peculiarities in how Bitcoin processes out of order, or "orphaned" transactions. We conducted experiments on Bitcoin testnet that suggest our technique reconstructs topology with precision and recall surpassing 90%. We also used TxProbe to take a snapshot of the Bitcoin testnet in just a few hours. TxProbe may be useful for future measurement campaigns of Bitcoin or other cryptocurrency networks.
André Greubel, Alexandra Dmitrienko, Samuel Kounev
In the Tor anonymity network, the distribution of topology information relies on the correct behavior of five out of the nine trusted directory authority servers. This centralization is concerning since a powerful adversary might compromise these servers and conceal information about honest nodes, leading to the full de-anonymization of all Tor users. Our work aims at distributing the work of these trusted authorities, such increasing resilience against attacks on core infrastructure components of the Tor network. In particular, we leverage several emerging technologies, such as blockchains, smart contracts, and trusted execution environments to design and prototype a system called SmarTor. This system replaces the directory authorities with a smart contract and a distributed network of untrusted entities responsible for bandwidth measurements. We prototyped SmarTor using Ethereum smart contracts and Intel SGX secure hardware. In our evaluation, we show that SmarTor produces significantly more reliable and precise measurements compared to the current measurement system. Overall, our solution improves the decentralization of the Tor network, reduces trust assumptions and increases resilience against powerful adversaries like law enforcement and intelligence services.
Abstract Electronic government (e-government) uses information and communication technologies to deliver public services to individuals and organisations effectively, efficiently and transparently. E-government is one of the most complex systems which needs to be distributed, secured and privacy-preserved, and the failure of these can be very costly both economically and socially. Most of the existing e-government systems such as websites and electronic identity management systems (eIDs) are centralized at duplicated servers and databases. A centralized management and validation system may suffer from a single point of failure and make the system a target to cyber attacks such as malware, denial of service attacks (DoS), and distributed denial of service attacks (DDoS). The blockchain technology enables the implementation of highly secure and privacy-preserving decentralized systems where transactions are not under the control of any third party organizations. Using the blockchain technology, exiting data and new data are stored in a sealed compartment of blocks (i.e., ledger) distributed across the network in a verifiable and immutable way. Information security and privacy are enhanced by the blockchain technology in which data are encrypted and distributed across the entire network. This paper proposes a framework of a decentralized e-government peer-to-peer (p2p) system using the blockchain technology, which can ensure both information security and privacy while simultaneously increasing the trust of the public sectors. In addition, a prototype of the proposed system is presented, with the support of a theoretical and qualitative analysis of the security and privacy implications of such system.
Peer to Peer (P2P) is a dynamic and self-organized technology, popularly used in File sharing applications to achieve better performance and avoids single point of failure. The popularity of this network has attracted many attackers framing different attacks including Sybil attack, Routing Table Insertion attack (RTI) and Free Riding. Many mitigation methods are also proposed to defend or reduce the impact of such attacks. However, most of those approaches are protocol specific. In this work, we propose a Blockchain based security framework for P2P network to address such security issues. which can be tailored to any P2P file-sharing system.
Zakaria Abou El Houda, Lyes Khoukhi, Abdelhakim Hafid
Nowadays, blockchain is seen as one of the main technological innovations. Many applications can rely on the blockchain to secure their exchanges. However, applications with private interest cannot rely on public blockchains. First, in a public blockchain, anyone can read the whole data of the blockchain. Second, anyone can participate to the "consensus process"; the process for determining the validity of each transaction. Consortium and fully private blockchains aim to combine forcefulness of blockchains with controlled consensus process and stricter permissions for deploying a node and joining the blockchain network. In both consortium and fully private blockchains, the number of peers on the blockchain network is very small in comparison with public blockchain. Nonetheless, by targeting the nodes of blockchains, an attacker can easily manage the whole blockchain and takes control of the consensus process to validate his illegitimate transactions. In this paper, to defend blockchain nodes from DNS amplification attacks, we propose a scalable and proactive solution in the context of software defined networks (SDN), named ChainSecure. ChainSecure consists of 3 schemes: (1) StateMap, a novel stateful mapping scheme (SMS) to perform a mapping one-to-one between DNS request and response; (2) Entropy calculation scheme (ECS) to measure the disorder / randomness of data using sFlow in order to detect illegitimate flows; (3) DNS DDoS Mitigation (DDM) module to effectively mitigate illegitimate DNS requests. The experimental results show that ChainSecure protects blockchain nodes and can detect/mitigate the attack quickly to achieve high accuracy in detecting illegitimate DNS traffic making it a promising solution to protect blockchain nodes from DNS amplification attacks.
The great convenience of electronic voting can improve the attendance and thus promote the process of democratization. However, the appearance of quantum computer severely threatens the security of those traditional electronic voting schemes. The efficiency of the current post-quantum electronic voting scheme is relatively low, some of them are unable to verify the validity of the ballots which results in a stronger security assumption. In this paper, we propose an efficient LWE-based verifiable electronic voting system whose security is based on the LWE assumption. To protect the user privacy, we tally homomorphically and verify the validity of ballot ciphertext through some interactions between two verification servers. In addition, a zero-knowledge proof can be utilized to verify the correctness of tally results. Finally, we analyze the properties and implement our system, the experimental results show the effectiveness of our system.
Blockchain technology has been seeing widespread interest as a means to ensure the integrity, confidentiality and availability of data in a trustless environment. They are designed to protect data from both internal and external cyberattacks by utilizing the aggregated power of the network to resist malicious efforts. In this article, we will create our own decentralized messaging application utilizing the Ethereum Whisper protocol. Our application will be able to send encrypted messages both securely and anonymously. We will utilize the Ethereum platform to deploy our blockchain network. This application would be resistant to most suppression tactics due to its distributed nature and adaptability of its communication protocol.
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques