Blockchain Papers

Abbas Yazdinejad, Reza M. Parizi, Ali Dehghantanha, Kim‐Kwang Raymond Choo

No abstract is available for this record.

Lei Yu, Xiaofang Zhao, Yan Jin, Hengyi Cai · 6 authors

Current blockchain consensus protocols have a triangle of contradictions in aspects of decentralization, security, and energy consumption, and cannot be synchronously optimized. We describe a design of two new blockchain consensus protocols, called “CHB-consensus” and “CHBD-consensus,” based on a consistent hash algorithm. Honest miners can fairly gain the opportunity to create blocks. They do not consume any extra computational power resources when creating new blocks, and such blocks can obtain the whole blockchain network to confirm consensus with fairness. However, malicious miners have to pay massive computational power resources for attacking the new block creation privilege or double-spending. Blockchain networks formed by CHB-consensus and CHBD-consensus are based on the same security assumption as that in Bitcoin systems, so they save a huge amount of power without sacrificing decentralization or security. We analyze possible attacks and give a rigorous but adjustable validation strategy. CHB-consensus and CHBD-consensus introduce a certification authority (CA) system, which does not have special management or control rights over blockchain networks or data structures, but carries the risk of privacy breaches depending on credibility and reliability of the CA system. Here, we analyze the robustness and energy consumption of CHB-consensus and CHBD-consensus, and demonstrate their advantages through theoretical derivation.

Wei Ren, Jingjing Hu, Tianqing Zhu, Yi Ren · 5 authors

No abstract is available for this record.

Ziyu Wang, Jianwei Liu, Qianhong Wu, Yanting Zhang · 6 authors

No abstract is available for this record.

Laizhong Cui, Shu Yang, Ziteng Chen, Yi Pan · 6 authors

Industrial Internet of Things (IIoT) has been widely used in many fields. Meanwhile, blockchain is considered promising to address the issues of the IIoT. However, the current blockchains have a limited throughput. In this article, we devise an efficient and secure blockchain protocol compacted directed acyclic graph (CoDAG) based on a compacted directed acyclic graph, where blocks are organized in levels and width. New-generated blocks in the CoDAG will be placed appropriately and point to those in the previous level, making it a well-connected channel. Transactions in the network will be confirmed in a deterministic period, and the CoDAG keeps a simple data structure at the same time. We also illustrate the attack strategies by adversary, and it is proved that our protocols are resistant to these attacks. Furthermore, we design a CoDAG-based IIoT architecture to improve the efficiency of the IIoT system. Experimental results show that the CoDAG achieves 164× Bitcoin's throughput and 77× Ethererum's throughput.

Akshay Kulkarni, Noor Ahmad Hazari, Mohammed Niamat

In trying to lower the costs of integrated circuit (IC) fabrication, the IC supply chain is becoming global. However, if the foundry or the supply chain, to which the fabrication process is outsourced, is not reliable or trustworthy, it may result in the quality of ICs being compromised. There have been well documented instances of counterfeit chips, and chips secretly implanted with Trojans, creeping into the supply chain. With the above background in mind, we propose to strengthen the supply chain process by attempting to use a very secure technique which has been widely used in many other fields, namely, the blockchain technology. Blockchain, first introduced for the security and mining of bitcoins, is one of the most trusted security techniques in today's world. In this paper, we propose a blockchain technology enabled `smart contract' approach for ensuring the security and trust of these ICs by tracking down the stage of alteration at which the chip may have been compromised in the IC supply chain.

Xingxiong Zhu

Each of the most popular blockchain platform, Bitcoin, Ethereum, and Hyperledger Fabric, varies in aspects of decentralization, permission, anonymity, and native-currency, has its own consensus mechanism, algorithm and implementation. In the mainstream blockchain technology, there are many common consensus algorithms. They differ in terms of computational complexity, fault-tolerance, and resilience. The performance, consistency, scalability, and efficiency of blockchain consensus mechanism need further improvement and optimization. Consensus mechanism and code implementation of Bitcoin, Ethereum and Hyperledger are analyzed, discussed and proposed.

Md Nazmul Islam, Sandip Kundu

The cost to develop a new integrated circuit (IC), its fabrication, debug and volume production has been escalating with scaling of transistor feature size. According to an IBS report, the cost of developing a System on Chip (SoC) at 14nm may be as high as $300 million [1]. The economics of semiconductor IC development favors high volume production, while high volume cannot be attained without developing an IC that serves a large number of applications. Some of these applications are in low margin Internet of Things (IoT) devices, where an SoC cannot command a high price. Consequently, without the ability to customize IC features after production, the price of an IC will be determined by its lowest priced application. This motivates the manufacturers to develop capabilities for post-production IC customization. The commodity microprocessor business offers an example of post-production customization, where a manufacturer can tailor cache size, number of cores and frequency of operation for a target market segment after a chip has been manufactured. Today, such customization is limited to one-time programming (OTP) for predetermined IC bins. In this paper, we explore how an IC can be programmed repeatedly and securely using a blockchain-based smart contract. This will enable users to upgrade IC features, or rent upgraded IC features for a fixed period after it has been purchased. The availability of such a system could, for example, allow a buyer to upgrade her processor from i3 to i5 after it has been purchased to scale to her computing needs in exchange of a payment made to the manufacturer. IC feature configuration is implemented by firmware updates from the manufacturer. The smart contract takes the feature configuration request from the IC as input and outputs the source of corresponding firmware. To support remote and authorized update by manufacturer, we propose an on-die hardware module that communicates with the smart contract and enforces its functionalities. Availability of this module also facilitates secure firmware update. The blockchain makes the update protocol secure and prevents users from obtaining unauthorized update.

Pekka Nikander, Juuso Autiosalo, Santeri Paavolainen

The upsurge of Industrial Internet of Things is forcing industrial information systems to enable less hierarchical information flow. The connections between humans, devices, and their digital twins are growing in numbers, creating a need for new kind of security and trust solutions. To address these needs, industries are applying distributed ledger technologies, aka blockchains. A significant number of use cases have been studied in the sectors of logistics, energy markets, smart grid security, and food safety, with frequently reported benefits in transparency, reduced costs, and disintermediation. However, distributed ledger technologies have challenges with transaction throughput, latency, and resource requirements, which render the technology unusable in many cases, particularly with constrained Internet of Things devices.To overcome these challenges within the Industrial Internet of Things, we suggest a set of interledger approaches that enable trusted information exchange across different ledgers and constrained devices. With these approaches, the technically most suitable ledger technology can be selected for each use case while simultaneously enjoying the benefits of the most widespread ledger implementations. We present state of the art for distributed ledger technologies to support the use of interledger approaches in industrial settings.

Jiasi, Weng, Jian Weng, Jia-Nan Liu, Yue, Zhang

Software-Defined Networking (SDN) separates the network control plane and data plane, which provides a network-wide view with centralized control (in the control plane) and programmable network configuration for data plane injected by SDN applications (in the application plane). With these features, a number of drawbacks of the traditional network architectures such as static configuration, non-scalability and low efficiency can be effectively avoided. However, SDN also brings with it some new security challenges, such as single-point failure of the control plane, malicious flows from applications, exposed network-wide resources and a vulnerable channel between the control plane and the data plane. In this paper, we design a monolithic security mechanism for SDN based on Blockchain. Our mechanism decentralizes the control plane to overcome single-point failure while maintaining a network-wide view. The mechanism also guarantees the authenticity, traceability, and accountability of application flows, and hence secures the programmable configuration. Moreover, the mechanism provides a fine-grained access control of network-wide resources and a secure controller-switch channel to further protect resources and communication in SDN.

Vikram Suresh, Sudhir Satpathy, Raghavan Kumar, Mark Anders · 10 authors

A 0.15mm2Bitcoin mining engine is fabricated in 14nm CMOS with highest-reported energy-efficiency of 0.063J/GHash at 250mV, 25°C. Fully-unrolled SHA256 datapath with Bitcoin-specific lookahead/deferred digest optimizations and 3-cycle distributed scheduler provide 31/56% digest/scheduler delay reductions, resulting in 10% higher energy-efficiency with dual-Vcc operation. 3-phase latch-based clocking with stretchable non-overlapping clocks eliminates all min-delay paths, reducing total sequential power consumption by 50%. Robust mining operation over a wide supply range of 230-900mV is demonstrated, with 10-760MHash/s throughput measured at 100°C.

Kun Wu, Guohao Dai, Xing Hu, Shuangchen Li · 7 authors

Blockchain applications have shown huge potential in various domains. Proof of Work (PoW) is the key procedure in blockchain applications, which exhibits the memory-bound characteristic and hinders the performance improvement of blockchain accelerators. In order to mitigate the "memory wall" and improve the performance of memory-hard PoW accelerators, using Ethash as an example, we optimize the memory architecture from two perspectives: 1) Hiding memory latency. We propose specialized context switch design to overcome the uncertain cycles of repetitive memory requests. 2) Increasing memory bandwidth utilization. We introduce on-chip memory that stores a portion of the Ethash directed acyclic graph (DAG) for larger effective memory bandwidth, and further propose adopting embedded NOR flash to fulfill the role. Then, we conduct extensive experiments to explore the design space of our optimized memory architecture for Ethash, including number of hash cores, on-chip/off-chip memory technologies and specifications. Based on the design space exploration, we finally provide the guidance for designing the memory-bound PoW accelerator. The experiment results show that our optimized designs achieve 8.7% -- 55% higher hash rate and 17% -- 120% higher hash rate per Joule compared with the baseline design in different configurations.

Ravi Kiran Raman, Roman Vaculín, Michael Hind, Sekou L. Remy · 9 authors

In high-stakes multi-party policy making based on machine learning and simulation models involving independent computing agents, a notion of trust in results is critical in facilitating transparency, accountability, and collaboration. Using a novel combination of distributed validation of atomic computation blocks and a blockchain-based immutable audit mechanism, this work proposes a framework for distributed trust in computations. In particular we address the scalability problem by reducing the storage and communication costs using a lossy compression scheme. This framework guarantees not only verifiability of final results, but also the validity of local computations, and its cost-benefit tradeoffs are studied using a synthetic example of training a neural network.

Md Nazmul Islam, Sandip Kundu

Globalization of IC supply chain has increased the risk of counterfeit, tampered, and re-packaged chips in the market. Counterfeit electronics poses a security risk in safety critical applications like avionics, SCADA systems, and defense. It also affects the reputation of legitimate suppliers and causes financial losses. Hence, it becomes necessary to develop traceability solutions to ensure the integrity of supply chain, from the time of fabrication to the end of product-life, which allows a customer to verify the provenance of a device or a system. In this article, we present an IC traceability solution based on blockchain. A blockchain is a public immutable database that maintains a continuously growing list of data records secured from tampering and revision. Over the lifetime of an IC, all ownership transfer information is recorded and archived in a blockchain. This safe, verifiable method prevents any party from altering or challenging the legitimacy of the information being exchanged. However, a chain of sales record is not enough to ensure provenance of an IC. There is a need for clone-proof method for securely binding the identity of an IC to the blockchain information. In this article, we propose a method of IC supply chain traceability via blockchain pegged to embedded physically unclonable function (PUF). The blockchain provides ownership transfer record, while the PUF provides unique identification for an IC allowing it to be linked uniquely to a blockchain. Our proposed solution automates hardware and software protocols using blockchain-powered Smart Contract that allows supply chain participants to authenticate, track, trace, analyze, and provision chips throughout their entire life cycle.

Hiroshi Watanabe, Howie Fan

The widespread computer network has been changing drastically and substantially since blockchain and IoT entered the stage. Blockchain is good at protecting data transactions between logical nodes with a desirable guaranty. Internet of Things (IoT), on the other hand, by providing ultimate convenience to consumers, is expected to give rise to many various merits in a broad business scene. The security of IoT is still an open problem and if blockchain can reinforce IoT security, as many authors have hoped in recent papers, these newcomers appear to make a good collaboration to reinforce IoT security. However, software copes with logical nodes and IoT involves a vast number of physical nodes (IoT devices). Enabling blockchain to protect IoT cannot be brought to reality without respectively identifying logical and physical nodes. This is identical to the Proof-of-Trust problem. In this article, we propose a conceptual solution—Blockchained IoT—and show that this concept is able to be realized on-chip level using mass-produced dynamical random access memory (DRAM). We have completed the first test of longevity and temperature dependence (−40 °C to 105 °C) to confirm the necessary characteristics for the 5G base stations that are known to have an issue of self-heating. Furthermore, we have coarsely evaluated the probability of two DRAM IC chips being associated with an identical cyber-physical chip identification accidentally. Then, such a probability is minimal.

Runchao Han, Nikos Foutris, Christos Kotselidis

Blockchain technology has become extremely popular, during the last decade, mainly due to the successful application in the cryptocurrency domain. Following the explosion of Bitcoin and other cryptocurrencies, blockchain solutions are being deployed in almost every aspect of transactional operations as a means to safely exchange digital assets between non-trusted parties. At the heart of every blockchain deployment is the consensus protocol, which maintains the consistency of the blockchain upon satisfying incoming transactions. Although many consensus protocols have been recently introduced, the most prevalent is Proof-of- Work, which scales the blockchain globally by converting the consensus problem to a competition based on cryptographic hash functions; a process called “mining”. The Proof-of- Work consensus protocol employs memory-hard algorithms in order to counteract ASIC or FPGA mining that may compromise the decentralization and democratization of the blockchain. Unfortunately, this leads to increased power consumption and scalability challenges since numerous processing units such as GPUs, FPGAs, and ASICs, are required to satisfy the ever-increasing operational requirements of blockchain deployments. In this paper, we perform an in-depth performance analysis and characterization of the most common memory-hard PoW algorithms running on NVIDIA GPUs. Motivated by our experimental findings, we apply a series of optimizations on Ethash algorithm, the consensus protocol of the Ethereum blockchain. The implemented optimizations accelerate performance by 14% and improve energy efficiency by 10% when executing on three NVIDIA GPUs. As a result, the optimized Ethash algorithm outperformed its fastest commercial implementation.

Aleksander Kuzmanovic

Provably neutral clouds are undoubtedly a viable solution to blockchain scaling. By optimizing the transport layer, not only can the throughput be fundamentally scaled up, but the latency could be dramatically reduced. Indeed, the latency distribution in today’s data centers is already biased toward microsecond timescales for most of the flows, with millisecond timescales residing only at the tail of the distribution. There is no reason why a BDN point of presence would not be able to achieve a similar performance. Adding dedicated optical infrastructure among such BDN points of presence would further alleviate throughput and reduce latency, creating the backbone of an advanced BDN. The key to this vision, however, lies in establishing trust by the blockchain ecosystem into the underlying networking infrastructure. This, in turn, is achieved by decoupling authority from infrastructure via a provably neutral network design.

Fang Wang, Zhaoyan Shen, Lei Han, Zili Shao

Blockchain's decentralized and consensus mechanism has attracted lots of applications, such as IoT devices. Blockchain maintains a linked list of blocks and grows by mining new blocks. However, the Blockchain mining consumes huge computation resource and energy, which is unacceptable for resource-limited embedded devices. This paper for the first time presents a ReRAM-based processing-in-memory architecture for Blockchain mining, called Re-Mining. Re-Mining includes a message schedule module and a SHA computation module. The modules are composed of several basic ReRAM-based logic operations units, such as ROR, RSF and XOR. Re-Mining further designs intra-transaction and inter-transaction parallel mechanisms to accelerate the Blockchain mining. Simulation results show that the proposed Re-Mining architecture outperforms CPU-based and GPU-based implementations significantly.

Carmelo Felicetti, Angelo Furfaro, Domenico Saccà, Massimo Vatalaro · 6 authors

No abstract is available for this record.

Chao Qiu, F. Richard Yu, Fangmin Xu, Haipeng Yao · 5 authors

Recently, rapid advances in information and communications technologies (ICTs) have improved the performance of software-defined industrial Internet of things (SDIIoT). Due to a variety of data, flows and smart devices in SDIIoT, a distributed SDN control plane is necessary. However, how to achieve consensus among controllers efficiently and safely is an intractable problem. In this paper, we use a permissioned blockchain approach to reach consensus in distributed SDIIoT. Since lots of data needs to be synchronized, and the throughput of traditional Byzantine fault tolerance protocol used in permissioned blockchain is limited by many aspects, i.e., the trust features of nodes in blockchain, the trust features of controllers in distributed SDIIoT, and the computing capacity of blockchain, we jointly consider these aspects to improve the throughput of permissioned blockchain. Accordingly, we formulate view change, access selection, and computing resources allocation as a joint optimization problem. This joint problem is highly dimensional, and is hard to be solved by traditional methods. Therefore, we propose a dueling deep Q-learning approach to address the problem. Simulation results show the effectiveness of our proposed scheme.

Zhancang Wang

In recent years, with Bitcoin taking the lead, the blockchain technology has been put in the spotlight as it introduced a method for multiple parties to achieve consensus without trust. Nevertheless, the according application is constrained due to its limitations in scalability. In this paper, we proposed a highly scalable consensus model based on majority voting cellular automata, namely the MOCA consensus, with a distinctive blockchain-based distributed ledger in which the state change of each node depends on its neighbors. MOCA consensus origins from the zero-temperature Ising model with spontaneous magnetization achieving scalability of number of nodes with high probability Byzantine fault tolerance.

Chao Qiu, F. Richard Yu, Haipeng Yao, Chunxiao Jiang · 6 authors

With the developments of communication technologies and smart manufacturing, Industrial Internet of Things (IIoT) has emerged. Software-defined networking (SDN), a promising paradigm shift, has provided a viable way to manage IIoT dynamically, called software-defined IIoT (SDIIoT). In SDIIoT, lots of data and flows are generated by industrial devices, where a physically distributed but logically centralized control plane is necessary. However, one of the most intractable problems is how to reach consensus among multiple controllers under complex industrial environments. In this paper, we propose a blockchain (BC)-based consensus protocol in SDIIoT, along with detailed consensus steps and theoretical analysis, where BC works as a trusted third party to collect and synchronize network-wide views between different SDN controllers. Specially, it is a permissioned BC. In order to improve the throughput of this BC-based SDIIoT, we jointly consider the trust features of BC nodes and controllers, as well as the computational capability of the BC system. Accordingly, we formulate view change, access selection, and computational resources allocation as a joint optimization problem. We describe this problem as a Markov decision process by defining state space, action space, and reward function. Due to the fact that it is difficult to solve this joint problem by traditional methods, we propose a novel dueling deep Q-learning approach. Simulation results are presented to show the effectiveness of our proposed scheme.

Elli Androulaki, Christian Cachin, Angelo De, Eleftherios Kokoris Kogias

Sharding, or partitioning the system’s state so that different subsets of participants handle it, is a proven approach to building distributed systems whose total capacity scales horizontally with the number of participants. Many distributed ledgers have adopted this approach to increase their performance, however, they focus on the permissionless setting that assumes the existence of a strong adversary. In this paper, we deploy channels for permissioned blockchains. Our first contribution is to adapt sharding on asset-management applications for the permissioned setting, while preserving liveness and safety even on transactions spanning across-channels. Our second contribution is to leverage channels as a confidentiality boundary, enabling different organizations and consortia to preserve their privacy within their channels and still be part of a bigger collaborative ecosystem. To make our system concrete we map it on top of Hyperledger Fabric.

Adrian Mizzi, Joshua Ellul, Gordon J. Pace

Blockchain and smart contract technology provide a means of decentralised computational agreements that are trusted and automated. By integrating Internet of Things (IoT) devices with blockchain systems and smart contracts, agreements can not only be confined to in-blockchain manipulation of state, however can enable agreements to interact on the physical world. This integration is non-trivial due to the limited resources on IoT devices and the heterogeneity of such an architecture. Such blockchain connected IoT devices typically require programming of smart contracts, edge blockchain nodes and the IoT devices. IoT embedded systems require expertise in low level development. Similarly, smart contract programming requires expertise with an extensive attention to detail, as even minor bugs can have catastrophic consequences. In this paper, we propose a macroprogramming approach for developing the different system components required for blockchain connected IoT devices including smart contracts, edge nodes and IoT devices from a monolithic description. In this manner, one can use a higher level of abstraction to develop an application, while still being able to generate code automatically which can be deployed on different nodes.