Shafiqah Azman, Dharini Pathmanathan, A. Thavaneswaran
During the COVID-19 pandemic, cryptocurrency prices showed abnormal volatility that attracted the participation of many investors. Studying the behaviour of volatility for the prices of cryptocurrency is an interesting problem to be investigated. This research implements the state space model framework for volatility incorporating the Kalman filter. This method directly forecasts the conditional volatility of five cryptocurrency prices (Bitcoin (BTC), Ethereum (ETH), Ripple (XRP), Litecoin (LTC) and Bitcoin Cash (BCH)) for 10,000 consecutive hours, i.e., approximately 417 days during the COVID-19 pandemic from 26 February 2020, 00:00 h until 18 April 2021, 00:00 h. The performance of this model is compared to the GARCH (1,1) model and the neural network autoregressive (NNAR) based on root mean square error (RMSE), mean absolute error (MAE) and the volatility plot. The autocorrelation function plot, histogram and the residuals plot are used to examine the model adequacy. Among the three models, the state space model gives the best fit. The state space model gives the narrowest confidence interval of volatility and value-at-risk forecasts among the three models.
Bu çalışmada, piyasa istikrarı ve yatırımcı ufkunu açıklayan, finansal zaman serilerinin normal dağılmadığını ve finansal zaman serilerinde kendine benzerlik özelliği olduğunu ifade eden fraktal piyasa hipotezinin iki gelişmekte olan, iki gelişmiş piyasada ve iki kripto varlıkta geçerliliğinin Hurst Üsteli- Yeniden ölçeklendirilmiş aralık (R/S) Analizi yöntemi aracılığıyla araştırılması amaçlanmıştır. MSCI sınıflamasına göre gelişmiş piyasalar olarak SP500 ve FTSE, gelişmekte olan piyasalar olarak Borsa İstanbul 100 ve Shanghai Endeksi incelemeye dahil edilmiştir. Kripto varlıklarda ise işlem hacmi en yüksek olan Bitcoin ve Ethereum değişkenleri incelemeye dahil edilmiştir. Çalışma bulgularına göre incelenen tüm endekslerde fraktal piyasa hipotezinin varlığı kabul edilirken, uzun hafızanın rolü ise değişmektedir. Tüm değişkenlerde Hurst üsteli değeri 0.5 değerinden yüksektir. Hurst üsteli sonuçlarına göre tüm değişkenlerde zaman serisinin kalıcı davranış gösterdiğine ilişkin hipotez kabul edilmiştir. Uzun hafızanın kalıcılığın en düşük olduğu değişken FTSE’dir. Gelişmekte olan borsalarda uzun hafıza ve kalıcılık gelişmiş borsalara göre daha yüksekken tüm değişkenler içerisinde uzun hafızanın en güçlü olduğu ve kalıcılığın en yüksek olduğu değişken ise Bitcoin’dir.
Blockchain-enabled smart contracts are subjected to several issues leading to vigorous attacks such as the decentralized autonomous organization (DAO) and the ParitySig bug on the Ethereum platform with disastrous consequences. Several solutions have been proposed. However, new threats are identified as technology evolves and new solutions are produced, while some older threats remain unsolved. Thus, the need to fill the gap with a more comprehensive survey on existing issues and solutions for researchers and practitioners arises. The resulting updated database will become an essential means for choosing a particular solution for a specific subject. In this review, the authors embrace mainly codifying security privacy and performance issues and their respective solutions. Each problem is attached to its corresponding solutions when they exist. A summary of the threats and solutions is provided as well as the relationship between threat importance and the given answers. They finally enumerate some directives for future works.
T. Deepa, N. Saraswathi, S. Hariprasad, KMS Praveen · 6 authors
Abstract Blockchain is an emerging technology which is known for its popularity and reliability. First introduced in 2008, it has now expanded to many areas such as IoT, cryptocurrency and Smart contracts. A blockchain consists of blocks assembled in the form of a chain. Data from each participant in the network is stored in these blocks. It is done in a block format called a series of transactions. The Internet of Things (IoT) has transformed many traditional lifestyles. The IoT has enabled cities, housing, pollution control, energy saving and intelligent transportation systems. Blockchain technology and the Internet of Things can increase the efficiency of peer-to-peer energy trading platforms. The open-source peer to peer (P2P) energy trading system is designed on the blockchain. Peer to peer (P2P) is a decentralized communication model in which each party has the same functionality and each party can initiate a communication session. The system collects real time data, monitors and controls it using MQTT Protocol. The trading activities takes place on a web interface which uses a public test Ethereum blockchain, they are tamper-proof. IoT is used to monitor and control the energy. The energy data is acquired and processed using Wi-Fi Based microcontrollers.
Some concepts become economically relevant as new technologies emerge, as is the case with cryptocurrencies in general, or Bitcoin and Ethereum in particular. Because of the importance of these tools, a thorough bibliometric study that allows us to obtain all information about cryptocurrencies is required. This study will aid related research that has been and is currently being conducted. The bibliometric analysis includes 11 articles that highlight the most related papers, research fields, countries, organizations, authors, publications, and trends over the last few years. Finally, the number of papers published has increased over the last three years. The analysis depicts the evolution of block chain technology, which is used in this type of crypto currency. And finally, will help the reader to find the answer for the research Question.
Georgios Fragkos, Jay Johnson, Eirini Eleni Tsiropoulou
A global transition to power grids with high penetrations of renewable energy generation is being driven in part by rapid installations of distributed energy resources (DER). New DER equipment includes standardized IEEE 1547-2018 communication interfaces and proprietary communications capabilities. Interoperable DER provides new monitoring and control capabilities. The existence of multiple entities with different roles and responsibilities within the DER ecosystem makes the Access Control (AC) mechanism necessary. In this paper, we introduce and compare two novel architectures, which provide a Role-Based Access Control (RBAC) service to the DER ecosystem’s entities. Selecting an appropriate RBAC technology is important for the RBAC administrator and users who request DER access authorization. The first architecture is centralized, based on the OpenLDAP, an open source implementation of the Lightweight Directory Access Protocol (LDAP). The second approach is decentralized, based on a private Ethereum blockchain test network, where the RBAC model is stored and efficiently retrieved via the utilization of a single Smart Contract. We have implemented two end-to-end Proofs-of-Concept (PoC), respectively, to offer the RBAC service to the DER entities as web applications. Finally, an evaluation of the two approaches is presented, highlighting the key speed, cost, usability, and security features.
This study sets out to explore the impacts of the Russian-Ukrainian conflict on worldwide financial markets by considering a large array of national currencies, precious metals and fuel, agricultural commodities and cryptocurrencies. Estimations span the period since the Russian invasion until the takeover of the Ukrainian city of Mariupol. Optimal portfolios are constructed for separate categories of financial assets for different levels of risk-aversion by investors. The Chinese yuan, gold, corn, soybeans, sugar and Bitcoin prove to be safe haven investments while the Japanese yen, natural gas, wheat and the combination of Bitcoin and Ethereum offer profit opportunities for risk-seekers. Notably, the agricultural commodities’ portfolio is the best performing while the cryptocurrency portfolio generates the worst risk-return trade-off. National currencies could act as safe havens in the place of gold when all types of assets can be combined. Natural gas is revealed to be the most reliable profit generator. Overall, high risk appetite does not result in large improvement in portfolios’ returns. This study sheds light on investors’ optimal decision-making during elevated geopolitical uncertainties and provides a compass for improving welfare.
Open access
Market Dynamics and Volatility
Environmental and Biological Research in Conflict Zones
Anokye Acheampong Amponsah, Adebayo Felix Adekoya, Benjamin Asubam Weyori
Healthcare fraud is a global problem affecting both developing and developed countries. It is the deliberate attempt of the perpetrators to take undue advantage of the inefficiencies in current healthcare systems. Fraud tends to deny legitimate beneficiaries of universal health coverage, especially those under health insurance protection. In this work, we propose using machine learning techniques and blockchain technology to detect and prevent fraud in healthcare, especially in claims processing. A decision tree classification algorithm is adopted to classify the original claims dataset. The extracted knowledge is programmed in the Ethereum blockchain smart contract to detect and prevent healthcare fraud. The comparative experimental results show that the best performing tool achieves a classification accuracy of 97.96% and a sensitivity of 98.09%. This means that the proposed system enhances the blockchain smart contract’s ability to detect fraud with an accuracy of 97.96%.
The management of construction projects requires adequate techniques to support the continual exchange of information across disciplines. Recent advances in Building Information Modelling (BIM) have exposed new ways for process and data integration with open data formats, process mapping, and terminology. In construction projects where multiple disciplines produce and share BIM data, mechanisms for defining information priority, provenance and suitability become necessary in order to have consistent and traceable use of data. This includes objects or collection of attributes for data objects that are associated with a discipline or organisation including clear identification of the transaction that has introduced the information. Blockchain can be used to record metadata of BIM objects such as the issuing discipline, object version and responsibility/ liability associated with the data. Blockchain can offer the capability to apply levels of “trust” to individual BIM objects and a more secured framework of collaboration across stakeholders. This paper proposes a Blockchain-based BIM data provenance model to support information exchange in construction projects. By testing the solution in a real-world bridge construction scenario, it has been shown that the approach can recognise the levels of competence and can improve the process of BIM implementation. The proposed approach gives stakeholders more confidence when sharing their BIM data, reduces costs, and improves risk contingencies in construction projects. The paper provides a cost analysis to evidence the implications of using Blockchain for BIM data provenance through an experimental framework supported by an Ethereum public test network. A front-end web page has also been created to facilitate interaction with smart contracts and to monitor the BIM data provenance process.
Smart contract has been the core of blockchain systems and other blockchain-based systems since Blockchain 2.0. Various operations on blockchain are performed through the invocation and execution of smart contracts. This leads to extensive combinations between blockchain, smart contract, Internet of Things (IoT) and Cyber-Physical System (CPS) applications, and then many blockchain-based IoT or CPS applications emerge to provide multiple benefits to the economy and society. In this case, obtaining a better understanding of smart contracts will contribute to the easier operation, higher efficiency and stronger security of those blockchain-based systems and applications. Many existing studies on smart contract analysis are based on similarity calculation and smart contract classification. However, smart contract is a piece of code with special characteristics and most of smart contracts are stored without any category labels, which leads to difficulties of smart contract classification. As the back end of a blockchain-based Decentralized Application (DApp) is one or several smart contracts, DApps with labeled categories and open source codes are applied to achieve a supervised smart contract classification. A three-phase approach is proposed to categorize DApps based on various data features. In this approach, 5,659 DApps with smart contract source codes and pre-tagged categories are first obtained based on massive collected DApps and smart contracts from Ethereum, State of the DApps and DappRadar. Then feature extraction and construction methods are designed to form multi-feature vectors that could present the major characteristics of DApps. Finally, a fused classification model consisting of KNN, XGBoost and random forests is applied to the multi-feature vectors of all DApps for performing DApp classification. The experimental results show that the method is effective. In addition, some positive correlations between feature variables and categories, as well as several user behavior patterns of DApp calls, are found in this paper.
Open access
2 source records
Blockchain Technology Applications and Security
Advanced Data and IoT Technologies
Advanced Steganography and Watermarking Techniques
Felix Engelmann, Thomas Kerber, Markulf Kohlweiss, Mikhail Volkhov
Privacy-oriented cryptocurrencies, like Zcash or Monero, provide fair transaction anonymity and confidentiality, but lack important features compared to fully public systems, like Ethereum. Specifically, supporting assets of multiple types and providing a mechanism to atomically exchange them, which is critical for e.g. decentralized finance (DeFi), is challenging in the private setting. By combining insights and security properties from Zcash and SwapCT (PETS 21, an atomic swap system for Monero), we present a simple zk-SNARKs based transaction scheme, called Zswap, which is carefully malleable to allow the merging of transactions, while preserving anonymity. Our protocol enables multiple assets and atomic exchanges by making use of sparse homomorphic commitments with aggregated open randomness, together with Zcash friendly simulation-extractable non-interactive zero-knowledge (NIZK) proofs. This results in a provably secure privacypreserving transaction protocol, with efficient swaps, and overall performance close to that of existing deployed private cryptocurrencies. It is similar to Zcash Sapling and benefits from existing code-bases and implementation expertise.
Rexford Nii Ayitey Sosu, Jinfu Chen, William Leslie Brown‐Acquaye, Ebenezer Owusu · 5 authors
<title>Abstract</title> A typical contract would necessitate the use of an intermediary, make a payment to them, then wait for the record to return. Through a smart contract, though, it is as easy as putting the bitcoin into the vending machine, and the products would be published instantly. Smart contracts are Blockchain-based autonomous software. On Ethereum, a vast number of smart contracts have been deployed. Meanwhile, transaction security vulnerabilities have resulted in significant financial damages and have harmed the contract layer’s ecological integrity on Blockchain. As a result, detecting contract bugs reliably and efficiently is a new yet critical problem. Currently, available identification approaches, such as Oyente and Securify, depend primarily on symbolic execution or analysis. Since symbolic execution necessitates the discovery of all executable routes or the study of dependence diagrams in a contract, these approaches are time-consuming. In this paper, we suggest SmartPol, a machine learning-based method for detecting vulnerabilities in smart contracts. First, we use a data pre-processor to clean up the data before extracting features and classifying them. Second, we present a PSOGSA-based method for data optimisation and function extraction and a TSVM-based approach for semi-supervised learning classification models to identify smart contract vulnerabilities automatically. On EtherScan, SmartPol was used to test 49512 real-world smart contracts. The experimental findings show SmartPol’s reliability and efficacy. When we use PSOGSA for function extraction and TSVM classification sets, SmartPol’s predictive precision and accuracy are over 96%, and the average prediction time is 4 seconds on each smart contract.
In this paper, we introduce SwarMED, a decentralized yet high throughput interoperability system for big biomedical data. SwarMED uses Etehreum blockchain for trustless security and Swarm p2p storage to handle high throughput transaction of big data. In SwarMED, we developed an indexing mechanism over the immutable storage of Swarm to achieve high-throughput while sharing millions of patient records and images among multiple parties. SwarMED achieved a high throughput of 250K medical records per second over a private network constructed over LSU-HPC cluster. This high throughput is 9x more comparing to conventional way of using p2p storage in conjunction with blockchain. This high throughput enables the patients to get realtime access to his comprehensive medical history and scientists to gain real-time access to different medical data for collaborative research complying to the constraints posed by existing laws. Our system-level analysis over different design alternatives over different transfer and storage architectures shows that, p2p storage platforms automatically provide significantly better scalability over traditional HTTP with increasing number of clients. Swarm provides 2x more I/O throughput and 10x less latency than IPFS, another p2p storage system making it a better choice for decentralized big data transaction.
Dendi Arya Raditya Prawira Putra, Yudha Purwanto, Marisa W. Paryasto
The existence of the Covid-19 virus, which was first announced at the end of 2019, in a short time was able to cause a pandemic. To overcome this, the government implemented a protocol that integrates Covid-19 test results and vaccination certificates into an application, with the aim that individuals can prove that they are free from Covid-19 infection and can return to normal activities. However, a centralized system is prone to single point of failure and data manipulation from the intervention of certain parties due to a lack of transparency. This paper proposed the use of Ethereum blockchain and smart contracts to solve this problem. By Using blockchain technology and smart contracts, the data management process will be more transparent since every transaction on the blockchain is recorded by each node. Blockchain also prevents a single point of failure because there are more than one data providers. The system that has been developed has fulfilled the security and privacy aspects of patient data by implementing password-based encryption on patient data. However, the system’s response time is strongly influenced by the computational capabilities of the Rinkeby network. On average, the system took 47,9 seconds to register a new certificate.
Blockchain is one of the most advanced technologies that play an important role in many different fields such as healthcare, capital markets and logistics. Among the many existing blockchain platforms, the integration of the Turingcomplete virtual programming engine with the blockchain makes the Ethereum blockchain one of the most paramount infrastructures for various types of applications, including but not limited to cryptocurrency trading, smart contracts, decentralised finance and metaverse. Nevertheless, Ethereum like many other computing systems, has fallen victim to vector attacks that exploit its vulnerabilities and have catastrophic consequences. Out of the need to protect Ethereum from such attacks, this paper proposes a novel deep learning model based on convolutional neural networks. The proposed model treats the transaction, which is the atomic entity in this platform, as a stochastic time series and then develops two specific task layers that are compatible with the traditional CNN architecture. The first layer is responsible for detecting the seasonal characteristics of the transactions, while the second layer is used for detecting the trend. These two layers are integrated with the traditional architecture to form a powerful temporal CNN architecture that can classify different types of attacks. The performance of the proposed model was evaluated from a different perspective using real transactions collected from the Ethereum main-net network. The results of the comprehensive evaluations show the ability of the proposed model to perfectly identify malicious transactions in the Ethereum blockchain.
Abstract The Robot Operating System (ROS) streamlines human processes, increasing the efficiency of various production tasks. However, the security of data transfer operations in ROS is still in its immaturity. Securing data exchange between several robots is a significant problem. This paper proposes \textit{AuthROS}, an Ethereum blockchain-based secure data sharing method, for robot communication. It is a ROS node authorization system capable of ensuring the immutability and security of private data flow between ROS nodes of any size. To ensure data security, AuthROS employs the smart contract for permission granting and identification, SM2-based key exchange, and SM4-based plaintext encryption techniques. In addition, we deploy a data digest upload technique to optimize data query and upload performance. Finally, the experimental findings reveal that AuthROS has strong security, time performance, and node forging in cases where data should be recorded and robots need to remain immobile.
Abstract Machine‐as‐a‐Service (MaaS) is an emerging service model for industrial appliances. With MaaS, machines are rented instead of being acquired, and their lifecycle is handled by an ecosystem of specialized actors, such as different independent maintenance companies certified for interventions on specific hardware. As the number of actors, clients, and providers involved in a MaaS ecosystem grows, maintaining mutual trust relationships between all involved parties and orchestrating MaaS operations in centralized fashion quickly becomes intractable. We present a blockchain‐based approach to providing MaaS in industrial settings where rented machines are equipped with IoT sensors, and where MaaS operations are orchestrated in a transparent, decentralized, and scalable way using a collection of smart contracts deployed over an infrastructure combining the Ethereum and InterPlanetary File System decentralized services. We detail the operations of MaaS, such as the lifecycle of management operations, and report on the performance of a prototype implementation deployed in the cloud.
Farhad Keramat, Jorge Peña Queralta, Tomi Westerlund
With the increasing ubiquity of autonomous robotic solutions, the interest in their connectivity and in the cooperation within multi-robot systems is rising. Two aspects that are a matter of current research are robot security and secure multi-robot collaboration robust to byzantine agents. Blockchain and other distributed ledger technologies (DLTs) have been proposed to address the challenges in both domains. Nonetheless, some key challenges include scalability and deployment within real-world networks. This paper presents an approach to integrating IOTA and ROS 2 for more scalable DLT-based robotic systems while allowing for network partition tolerance after deployment. This is, to the best of our knowledge, the first implementation of IOTA smart contracts for robotic systems, and the first integrated design with ROS 2. This is in comparison to the vast majority of the literature which relies on Ethereum. We present a general IOTA+ROS 2 architecture leading to partition-tolerant decision-making processes that also inherit byzantine tolerance properties from the embedded blockchain structures. We demonstrate the effectiveness of the proposed framework for a cooperative mapping application in a system with intermittent network connectivity. We show both superior performance with respect to Ethereum in the presence of network partitions, and a low impact in terms of computational resource utilization. These results open the path for wider integration of blockchain solutions in distributed robotic systems with less stringent connectivity and computational requirements.
Learning heterogeneous graphs consisting of different types of nodes and edges enhances the results of homogeneous graph techniques. An interesting example of such graphs is control-flow graphs representing possible software code execution flows. As such graphs represent more semantic information of code, developing techniques and tools for such graphs can be highly beneficial for detecting vulnerabilities in software for its reliability. However, existing heterogeneous graph techniques are still insufficient in handling complex graphs where the number of different types of nodes and edges is large and variable. This paper concentrates on the Ethereum smart contracts as a sample of software codes represented by heterogeneous contract graphs built upon both control-flow graphs and call graphs containing different types of nodes and links. We propose MANDO, a new heterogeneous graph representation to learn such heterogeneous contract graphs’ structures. MANDO extracts customized meta-paths, which compose relational connections between different types of nodes and their neighbors. Moreover, it develops a multi-metapath heterogeneous graph attention network to learn multi-level embeddings of different types of nodes and their metapaths in the heterogeneous contract graphs, which can capture the code semantics of smart contracts more accurately and facilitate both fine-grained line-level and coarse-grained contract-level vulnerability detection. Our extensive evaluation of large smart contract datasets shows that MANDO improves the vulnerability detection results of other techniques at the coarse-grained contract level. More importantly, it is the first learning-based approach capable of identifying vulnerabilities at the fine-grained line-level, and significantly improves the traditional code analysis-based vulnerability detection approaches by 11.35% to 70.81% in terms of F1-score.
At present, millions of Ethereum smart contracts are created per year and attract financially motivated attackers. However, existing analyzers do not meet the need to precisely analyze the financial security of large numbers of contracts. In this paper, we propose and implement FASVERIF, an automated analyzer for fine-grained analysis of smart contracts' financial security. On the one hand, FASVERIF automatically generates models to be verified against security properties of smart contracts. On the other hand, our analyzer automatically generates the security properties, which is different from existing formal verifiers for smart contracts. As a result, FASVERIF can automatically process source code of smart contracts, and uses formal methods whenever possible to simultaneously maximize its accuracy. We evaluate FASVERIF on a vulnerabilities dataset by comparing it with other automatic tools. Our evaluation shows that FASVERIF greatly outperforms the representative tools using different technologies, with respect to accuracy and coverage of types of vulnerabilities.
Due to the decentralized and public nature of the blockchain ecosystem, malicious activities on the Ethereum platform impose immeasurable losses on users. At the same time, the transparency of cryptocurrency transactions provides a unique opportunity to analyze illegal activities, such as phishing scams, from a network perspective. Most existing phishing scam detection methods focus primarily on analyzing account interaction networks, which limits their ability to uncover transaction behavior patterns embedded within transaction interactions. To address this, we construct theTransactionSubGraphNetwork (TSGN) by using transaction subgraphs as basic elements and further propose a novel framework for Ethereum phishing account detection. Specifically, we rebuild the graph structures via three well-designed mapping mechanisms, yielding TSGN and its two variants, i.e., Directed-TSGN and Temporal-TSGN, to obtain direction-aware and time-aware transfer flow features. By further incorporating the mapping strategy into transaction multidigraphs, we develop the Multiple-TSGN, which could preserve more transaction flow features while concurrently reducing the time consumption of modeling large-scale networks. TSGN models based on transaction subgraph interactions can capture complex higher-order dependencies, which lay beyond the reach of models that exclusively capture pairwise account interactions. As a general framework, our model can incorporate various feature extraction methods to improve the performance of phishing detection. Extensive experimental results on Ethereum datasets show that our method achieves superior performance in phishing detection, yielding 3.27%$\sim$6.71% relative improvement over previous state-of-the-art.
Eder J. Scheid, Muriel Figueredo Franco, Fabian Kuffer, Niels Kubler · 6 authors
Network Functions Virtualization (NFV) has been a key part of evolving communication systems in the last few years. However, the life-cycle management of Virtual Network Functions (VNF) is still a not trivial task. Blockchains (BC), due to their decentralization and immutability characteristics, together with the automation provided by Smart Contracts (SC), can be employed to enable such automated and trustworthy VNF management.Thus, this paper proposes VeNiCE to automate the deployment and life-cycle management of VNFs using events emitted on SCs. VeNiCE provides automation and auditability by relying on a BC to provide a decentralized approach for VNF management, which performs management actions, such as VNF deployment and deletion, and based on events and communicates with an SC to provide immutable logging of the VNF life-cycle. VeNiCE provides (i) a frontend for user interaction, (ii) a backend implementing the communication with the NFV framework, and (iii) an SC that emits events, stores VNF allocations, and authenticates users. A prototype of VeNiCE was developed and deployed in the Ethereum BC using OpenStack Tacker as an NFV platform. Experiments were conducted in a real-world deployment of such a prototype to analyze the economic costs of using SCs and the time required to process requests by each component of VeNiCE and the BC. Those results obtained show VeNiCE’s feasibility, highlight its benefits achieved with the automation and provide insights on reducing costs by exploring additional BC platforms and different deployment types, which introduce centralization and management concerns.
Cyber Threat Intelligence (CTI) is the knowledge of cyber and physical threats that help mitigate potential cyber attacks. The rapid evolution of the current threat landscape has seen many organisations share CTI to strengthen their security posture for mutual benefit. However, in many cases, CTI data contains attributes (e.g., software versions) that have the potential to leak sensitive information or cause reputational damage to the sharing organisation. While current approaches allow restricting CTI sharing to trusted organisations, they lack solutions where the shared data can be verified and disseminated `differentially' (i.e., selective information sharing) with policies and metrics flexibly defined by an organisation. In this paper, we propose a blockchain-based CTI sharing framework that allows organisations to share sensitive CTI data in a trusted, verifiable and differential manner. We discuss the limitations associated with existing approaches and highlight the advantages of the proposed CTI sharing framework. We further present a detailed proof of concept using the Ethereum blockchain network. Our experimental results show that the proposed framework can facilitate the exchange of CTI without creating significant additional overheads.