Conventional access control models such as RBAC and ABAC have been inefficient for IoT systems due to the raised security concerns. Blockchain technology has been effective to provide decentralized solutions for maintaining data, addressing the challenges of auditability, privacy, and scalability as well as eliminating a single point of failure problem in recent years IoT access control management. This work presents a review of access control frameworks using blockchain technology for IoT devices.
A boardroom election is an election with a small number of voters carried out with public communications. We present BVOT, a self-tallying boardroom voting protocol with ballot secrecy, fairness (no tally information is available before the polls close), and dispute-freeness (voters can observe that all voters correctly followed the protocol). BVOT works by using a multiparty threshold homomorphic encryption system in which each candidate is associated with a masked unique prime. Each voter engages in an oblivious transfer with an untrusted distributor: the voter selects the index of a prime associated with a candidate and receives the selected prime in masked form. The voter then casts their vote by encrypting their masked prime and broadcasting it to everyone. The distributor does not learn the voter's choice, and no one learns the mapping between primes and candidates until the audit phase. By hiding the mapping between primes and candidates, BVOT provides voters with insufficient information to carry out effective cheating. The threshold feature prevents anyone from computing any partial tally---until everyone has voted. Multiplying all votes, their decryption shares, and the unmasking factor yields a product of the primes each raised to the number of votes received. In contrast to some existing boardroom voting protocols, BVOT does not rely on any zero-knowledge proof; instead, it uses oblivious transfer to assure ballot secrecy and correct vote casting. Also, BVOT can handle multiple candidates in one election. BVOT prevents cheating by hiding crucial information: an attempt to increase the tally of one candidate might increase the tally of another candidate. After all votes are cast, any party can tally the votes.
Using hard-fork mechanism on the blockchain to recover the losses caused by attacks contradicts the immutable characteristic of a blockchain system. To prevent malicious transactions from getting into blockchains in advance, we propose a runtime hook technique to synchronize and analyze the ongoing transactions exposed to the Ethereum transaction pool. Having a complete view of the past and the ongoing transactions, we can identify and enforce abortion of malicious transactions and prevent losses due to attacks being executed and recorded in the blockchain. Specifically, we modify the Ethereum source code to instrument the entry point of a node to synchronize data received from the Ethereum P2P network and systematically scan suspicious patterns in transactions to identify potential attacks. As a proof-of-the-concept, we show how to deploy the proposed runtime hook system on a private blockchain system, such that we can detect and prevent transactions of double spending on the 51% attack and reentrancy attack of smart contracts.
The Ethereum cryptocurrency system becomes prevalent with the increasing number of daily transactions. It is a high-quality channel to secretly transfer information because senders and recipients are pseudonymous and transactions are tamper-resistant. Several existing covert channels have been designed for several years. However, most of the existing covert channels can either be detected by their special patterns or have low embedding rate. In this paper, we first use the VALUE field of a transaction in the Ethereum system to construct a HMAC-based multiple-bit embedding (HMAC-based MBE) scheme. We further proposed a Hash-based multiple-bit embedding (Hash-based MBE) scheme to enhance the covertness. Theoretical and experimental analysis show that both schemes have either higher embedding rate or better covertness than that of the existing works.
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
Since the initial launch of Bitcoin by Satoshi Nakamoto in 2009, decentralized digital currencies have long been of major interest in both the academia and the industry. Till today, there are more than 3000 different cryptocurrencies over the internet. Each one relies on mathematical soundness and cryptographic wit to provide unique properties in addition to securing basic correctness. A common misbelief for cryptocurrencies is that they provide complete anonymity by replacing people's real-life identity with a randomly generated wallet address in payments. However, this "pseudonymity" is easily breakable under the public ledger. Many attacks demonstrate ways to deanonymize people through observing the transaction patterns or network interactions. Thus, cryptocurrency fungibility has become a popular topic in the research community. This report reviews a partial list of existing schemes and describes an alternative implementation, Eth-Tumbler. Eth-Tumbler utilizes layered encryption and multiple signatures and thus efficiently hides a user under k-anonymity.
Open access
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cs.CR
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
We propose a secure and efficient implementation of fungible tokens on Bitcoin. Our technique is based on a small extension of the Bitcoin script language, which allows the spending conditions in a transaction to depend on the neighbour transactions. We show that our implementation is computationally sound: that is, adversaries can make tokens diverge from their ideal functionality only with negligible probability.
Yamuna Rosasooria, Abd Kadir Mahamad, Sharifah Saon, Mohd Anuar Mat Isa · 6 authors
Electronically voting process without paper and the ballot box, namely electronic voting (e-voting), required some improvement, especially in terms of security elements. This is against the anonymize properties of the e-voting system. Therefore, a blockchain e-voting system was proposed which have a secure and transparency features to deploy during the Student Representative Council (SRC) election in Universiti Tun Hussein Onn Malaysia (UTHM). Blockchain technology ensured all aspects such as transparency, security, and auditability were achieved without sacrificing the privacy of voters. In this study, e-voting using a blockchain system was developed to detect the fraud that occurs during the voting session using Solidity language. A total of 3 cases were analyzed and a questionnaire was done to evaluate the proposed system. Analysis of respondents gave positive perception with a mean value of 4.5, 4.6, and 4.9, for 1st, 2nd,and 3rdCase respectively. To sum up, the proposed system can shorter the time for the voting process and diminishes the expense because of no need to print out the ballot.
Elizabeth C. Crites, Mary Maller, Sarah Meiklejohn, Rebekah Mercer
Token-curated registries (TCRs) are a mechanism by which a set of users are able to jointly curate a reputable list about real-world information. Entries in the registry may have any form, so this primitive has been proposed for use—and deployed—in a variety of decentralized applications, ranging from the simple joint creation of lists to helping to prevent the spread of misinformation online. Despite this interest, the security of this primitive is not well understood, and indeed existing constructions do not achieve strong or provable notions of security or privacy. In this paper, we provide a formal cryptographic treatment of TCRs as well as a construction that provably hides the votes cast by individual curators. Along the way, we provide a model and proof of security for an underlying voting scheme, which may be of independent interest. We also demonstrate, via an implementation and evaluation, that our construction is practical enough to be deployed even on a constrained decentralized platform like Ethereum.
J Dharani, K Sundarakantham, Kunwar Singh, S. Mercy Shalinie
Blockchain technology has gained its attention from its application in bitcoin which circumvented the problem of double spending that existed in the prior digital currencies, through validation. Particularly permissioned blockchain framework became popular with organizations forming consortium that allowed only authorized entities to participate in the network. Hyperledger Fabric, a popular distributed ledger technology hosted by Linux Foundation has remarkable features because of the fact that it is open source. It stands out from other frameworks as it focuses on the privacy-preserving requirements of the enterprises. Apart from only allowing authenticated organizations to participate in the network it implements channels that allows a subset of organizations to communicate concealing the existence of such a channel to other members. Optionally fabric also provides anonymity and unlinkability of the participating clients through a cryptographic protocol suite called Idemix that operates based on zero-knowledge proofs. Fabric follows the execute-order-validate transaction flow as opposed to order-execute flow that had certain limitations in other platforms. For executing the transactions submitted by the clients, fabric has designated endorsing peers which holds the smart contract - programmable business logic. Endorsing peers or endorsers execute the transactions and attach their signatures to the results for validation purpose. But revealing the endorser identities may be a problem when there is conflict of interest among the enterprises. Hence to have an unbiased flow of work it is important to conceal the endorser identity. According to [1] anonymization of endorsing peers is still a open problem in fabric community. We propose a solution to this problem which uses linkable threshold ring signatures that conceals the identity of endorsers. Ring signatures are known for preserving the privacy of the signer in a group. Threshold ring signature allows t-out-of-n signers to collaborate on the signing procedure. Employing threshold ring signature implicitly addresses one more problem stated in [10] where the verifiers need to manually count the valid ring signature that increases the verification time. This process of separately verifying each of the signatures and checking if the number of signatures is more than the threshold value is replaced by having just one threshold signature collaboratively signed by the required endorsers.
Fáber D. Giraldo, Barbosa Milton C., Carlos E. Gamboa
Blockchain technology has been presented as a support for trust needs between transactions in electronic information systems. Its successful use in cryptocurrencies has allowed it to explore its capabilities in commercial, industrial, and service systems, backed by the operational alternatives offered by Ethereum Smart Contracts and the cryptographic security of public and private key. These keys are used as a way to make online transactions anonymously, with the guarantee offered by the Blockchain network that they are executed safely. With the above in mind, this concept can be extended to the electoral processes, thus allowing its application in electronic voting systems, especially when the protocols currently used lack the trust factor between the different social actors. This document presents a proof of concept in which Blockchain and other technologies are applied, to allow interaction as an electronic voting system for the election of unique candidates. This has been achieved through the specification of an architecture designed especially for electoral processes, from which it is implemented and a simulation is carried out in order to obtain data that generates value, when evaluating Blockchain technology as an alternative to current voting systems.
Michael Rodler, Wenting Li, Ghassan Karame, Lucas Davi
Recent attacks exploiting errors in smart contract code had devastating consequences thereby questioning the benefits of this technology. It is currently highly challenging to fix errors and deploy a patched contract in time. Instant patching is especially important since smart contracts are always online due to the distributed nature of blockchain systems. They also manage considerable amounts of assets, which are at risk and often beyond recovery after an attack. Existing solutions to upgrade smart contracts depend on manual and error-prone processes. This paper presents a framework, called EVMPatch, to instantly and automatically patch faulty smart contracts. EVMPatch features a bytecode rewriting engine for the popular Ethereum blockchain, and transparently/automatically rewrites common off-the-shelf contracts to upgradable contracts. The proof-of-concept implementation of EVMPatch automatically hardens smart contracts that are vulnerable to integer over/underflows and access control errors, but can be easily extended to cover more bug classes. Our extensive evaluation on 14,000 real-world (vulnerable) contracts demonstrate that our approach successfully blocks attack transactions launched on these contracts, while keeping the intended functionality of the contract intact. We perform a study with experienced software developers, showing that EVMPatch is practical, and reduces the time for converting a given Solidity smart contract to an upgradable contract by 97.6 %, while ensuring functional equivalence to the original contract.
Elections are the foundations of democracy. To uphold democratic principles, researchers have proposed systems that ensure the integrity of elections. It is a highly interdisciplinary field, as it can be studied from a technical, legal or societal points of view. While lawyers give a legal framework to the voting procedures, security researchers translate these rules into technical properties that operational voting systems must satisfy, notably privacy and verifiability. If Privacy aims to protect vote-secrecy and provide coercion-resistance to the protocol, Verifiability allows voters to check that their vote has been taken into account in the general outcome, contributing to the assurance of the integrity of the elections. To satisfy both properties in a voting system, we rely on cryptographic primitives such as encryption, signatures, commitments schemes, or zero-knowledge proofs, etc. Many protocols, paper-based or electronic-based, have been designed to satisfy these properties. Although the security of some protocols, and their limits, have been analysed from a technical perspective, the usability has often been shown to have very low rates of effectiveness. The necessary cryptographic interactions have already shown to be one contributor to this problem, but the design of the interface could also contribute by misleading voters. As elections typically rarely happen, voters must be able to understand the system they use quickly and mostly without training, which brings the user experience at the forefront of the designed protocols. In this thesis, the first contribution is to redefine privacy and verifiability in the context of tracker-based verifiable schemes. These schemes, using a so-called tracking number for individual verification, need additional user steps that must be considered in the security evaluation. These security definitions are applied to the boardroom voting protocol F2FV used by the CNRS, and the e-voting protocol Selene, both use a tracker-based procedure for individual verifiability. We provide proofs of security in the symbolic model using the Tamarin prover. The second contribution is an implementation of the Selene protocol as a mobile and a web application, tested in several user studies. The goal is to evaluate the usability and the overall user experience of the verifiability features, as well as their understanding of the system through the evaluation of mental models. The third contribution concerns the evaluation of the voters' understanding of the coercion mitigation mechanism provided by Selene, through a unique study design using game theory for the evaluation of voters. Finally, the fourth contribution is about the design of a new voting scheme, Electryo, that is based on the Selene verification mechanisms but provides a user experience close to the standard paper-based voting protocols.
Vasileios Yfantis, Helen C. Leligou, Klimis Ntalianis
This article discusses the concept of blockchain and its application to public administration research as a tool to increase trust in the government. The contribution of this article is that it unveils the advantages and disadvantages of blockchain so that both decision-makers (who intend to adopt this innovative technology to increase the transparency of the transactions in the public sector) and users (citizens and public servants) are well informed and prepared.
Iñigo Querejeta-Azurmendi, David Arroyo, Jorge López Hernández-Ardieta, Luis Hernández Encinas
This paper proposes NetVote, an internet voting protocol where usability and ease in deployment are a priority. We introduce the notion of strict coercion resistance, to distinguish between vote-buying and coercion resistance. We propose a protocol with ballot secrecy, practical everlasting privacy, verifiability and strict coercion resistance in the re-voting setting. Coercion is mitigated via a random dummy vote padding strategy to hide voting patterns and make re-voting deniable. This allows us to build a filtering phase with linear complexity, based on zero knowledge proofs to ensure correctness while maintaining privacy of the process. Voting tokens are formed by anonymous credentials and pseudorandom identifiers, achieving practical everlasting privacy, where even if dealing with a future computationally unbounded adversary, vote intention is still hidden. It is not assumed for voters to own cryptographic keys prior to the election, nor store cryptographic material during the election. This property allows voters not only to vote multiple times, but also from different devices each time, granting the voter a vote-from-anywhere experience. This paper builds on top of the paper published in CISIS’19. In this version, we modify the filtering. Moreover, we formally define the padding technique, which allows us to perform the linear filtering scheme. Similarly we provide more details on the protocol itself and include a section of the security analysis, where we include the formal definitions of strict coercion resistance and a game based definition of practical everlasting privacy. Finally, we prove that NetVote satisfies them all.
Marta Poblet, Darcy W E Allen, Oleksii Konashevych, Aaron M. Lane · 5 authors
Oracles were trusted sources of knowledge for public deliberation in classical Athens. Very much like expert and technical knowledge, divine advice was embedded in the deliberation and decision-making process of the democratic Assembly. While the idea of religious divination is completely out of place in our contemporary democracies, oracles made a technological comeback with modern computer science and cryptography and, more recently, the emergence of the blockchain as a “trust machine”. This paper reviews the role of oracles in Athenian democracy and, stemming from the renewed use of the term in computer sciences and cryptography, analyses the case of oracles in the nascent blockchain ecosystem. The paper also proposes a sociotechnical approach to the use of distributed oracles as informational devices to assist deliberative processes in digital democracy settings, and considers the limits that such an approach may face.
Sam Goundar, Rahul Chand, Fariha Tafsil, Reema Mala · 5 authors
The emergence of the Internet has opened a world of possibilities to connect and interact through web portals and to exchange information over the network. In the past decade, buying and selling of goods and services online has become more common through e-commerce. With the advent of Cryptocurrencies, the possibilities of e-commerce have reached new heights for all web users who see potential in this technology. Cryptocurrencies have opened new dimensions based on a Blockchain technology for e-commerce through decentralization; increased privacy and digitalization of coins allow users to anonymously trade online. This has become more common in the Darknet, which is simply the unindexed side of the Internet. This chapter compares the three Cryptocurrencies, namely bitcoin, ethereum and monero, used for e-commerce in the Darknet.
Prabhat Kumar, Randhir Kumar, Govind P. Gupta, Rakesh Tripathi
Abstract With the advancement of blockchain technology, and the proliferation of Internet of things (IoT)‐driven devices, the blockchain‐IoT applications is changing the perception and working infrastructure of smart networks. Blockchain supports decentralized architecture and provides secure management, authentication, and access to IoT systems by deploying smart contracts provided by Ethereum. The growing demand and expansion of blockchain‐IoT systems is generating large volume of sensitive data. Moreover, distributed denial‐of‐service (DDoS) attacks are the most challenging threats to smart contracts in blockchain‐IoT systems. The 2016 decentralized autonomous organization and 2017 parity wallet attacks exposed the critical fault‐lines among Ethereum smart contracts. Currently, there is no security mechanism available for smart contracts after its deployment in blockchain‐IoT systems. In order to address these challenges, first we use two artificial intelligence techniques, random forest (RF) and XGBoost that gives full autonomy in decision making capabilities in the proposed security framework. Second, for data load balancing and distributed file storage of IoT data, interplanetary file system is suggested. Finally, we are the first to propose a distributed framework based on fog computing to detect DDoS attacks in smart contracts. The performance of the detection system is evaluated using actual IoT dataset, namely, BoT‐IoT. The proposed system is evaluated in terms of accuracy (AC), detection rate (DR), and false alarm rate (FAR). The results confirms the superiority of the proposed framework over some of the recent state‐of‐art techniques in detecting rare attacks. The proposed framework has achieved DR up to 99.99% using RF by using 10 features of BoT‐IoT dataset.
Efficient and reliable access control in smart cities is critical for the protection of various resources for decision making and task execution. Existing centralized access control schemes suffer from the limitations of single point of failure, low reliability, and poor scalability. This article, therefore, proposes a distributed and reliable access control framework for smart cities by combining the blockchain smart contract technology and the attribute-based access control (ABAC) model. The framework consists of one policy management contract (PMC) for managing the ABAC policies, one subject attribute management contract (SAMC) for managing the attributes of subjects (i.e., entities accessing resources), one object attribute management contract (OAMC) for managing the attributes of objects (i.e., resources being accessed), and one access control contract (ACC) for performing the access control. To show the feasibility of the proposed framework, we construct a local private Ethereum blockchain system to implement the four smart contracts and also conduct experiments to evaluate the monetary cost as well as to compare the proposed framework with an existing access control list (ACL)-based scheme. The experimental results show that although the proposed scheme consumes more money than the ACL-based scheme at the deployment stage, it introduces less monetary cost during the system running especially for large-scale smart cities.
In order to avoid the demerits of Direct Democracy (DD) and Representative Democracy (RD), recently a democratic reform called Liquid Democracy (LD) was introduced which is a combination of DD and RD that gives the people full decisional control either by voting directly or by entrusting their voting power to a representative for some political ideologies or bills. Our work attempts to study the democratic models based on accuracy and competence parameters. Further a liquid democracy voting protocol is proposed and implemented on a block chain based distributed ledger which is capable of fighting attacks of integrity and non-repudiation while ensuring authenticity of the votes. This system would be transparent thus ensuring people about the legitimacy of their delegation of votes and direct votes. This is a big step up from the current existing system of EVM’s that do not guarantee this level of security.
Majd Soud, Sigureur Helgason, Gísli Hjálmtýsson, Mohammad Hamdaqa
Electronic voting (e-voting) plays a crucial role in democratic countries. Unfortunately, implementing a trusted e-voting system is always a challenge. Scholars have been trying to propose solutions to improve e-voting systems. However, existing e-voting approaches still need to adopt new technologies to maintain their integrity and modernity. Unlike other technologies that were used in e-voting, blockchain has the potential for perfecting e-voting requirements and fostering trust in e-voting systems. The first part of this paper presents a state-of-the-art review of blockchain-based e-voting implementations. The second part proposes a blockchain-based e-voting system (TrustVote). TrustVote was realised using public and permissioned blockchain. This work results show that the permissioned blockchain-based implementation of TrustVote outperforms the identical version of the same system that uses public blockchain. The results also show that while several challenges and requirements still need to be addressed, using permissioned blockchain for implementing an e-voting system can help to satisfy many of the requirements for e-voting and pave the road for a new generation of e-voting systems that people can trust.
Internet Traffic Analysis and Secure E-voting
Cryptography and Data Security
Advanced Steganography and Watermarking Techniques
Amrita Dhillon, Grammateia Kotsialou, Peter McBurney, Luke Riley
This work discusses the potential of a blockchain based infrastructure for a decentralised online voting platform. When compared to paper based voting, online voting can vastly increase the speed that votes can be counted, expand the overall accessibility of the election system and decrease the cost of turnout. Yet despite these advantages, online voting for political office is subject to fraud at various levels due to its centralised nature. In this paper, we describe a general architecture of a centralised online voting system and detail which areas of such a system are vulnerable to electoral fraud. We then proceed to introduce the key ideas underlying blockchain technology as a decentralised mechanism that can address these problems. We discuss the advantages and weaknesses of the blockchain technology, the protocols the technology uses and what criteria a good blockchain protocol should satisfy (depending on the voting application). We argue that the decentralisation inherent in the blockchain technology could increase the public's trust in national elections, as well as eliminate voter impersonation and double voting. We conclude with a discussion regarding how economists and social scientists can collaborate with the blockchain community in a research agenda on the design of efficient blockchain protocols and new voting systems such as liquid democracy.