Sandi Gec, Dejan Lavbič, Marko Bajec, Vlado Stankovski
Today, container-based virtualization is very popular due to the lightweight\nnature of containers and the ability to use them flexibly in various\nheterogeneously composed systems. This makes it possible to collaboratively\ndevelop services by sharing various types of resources, such as\ninfrastructures, software and digitalized content. In this work, our home made\nvideo-conferencing (VC) system is used to study resource usage optimisation in\nbusiness context. An application like this, does not provide monetization\npossibilities to all involved stakeholders including end users, cloud\nproviders, software engineers and similar. Blockchain related technologies,\nsuch as Smart Contracts (SC) offer a possibility to address some of these\nneeds. We introduce a novel architecture for monetization of added-value\naccording to preferences of the stakeholders that participate in joint software\nservice offers. The developed architecture facilitates use case scenarios of\nservice and resource offers according to fixed and dynamic pricing schemes,\nfixed usage period, prepaid quota for flexible usage, division of income,\nconsensual decisions among collaborative service providers, and constrained\nbased usage of resources or services. Our container-based VC service, which is\nbased on the Jitsi Meet Open Source software is used to demonstrate the\nproposed architecture and the benefits of the investigated use cases.\n
Envisioned 5G use cases arise challenges around the realization of inter-domain relationships beyond traditional Border Gateway Protocol (BGP) peering, e.g. end-to-end service deployments tailored to specific business needs (a.k.a. slices). Blockchain technologies bring consensus among decentralized non-trusting counterparts as a shared ledger, offering potential approaches for multi-administrative domain networking seeking agile, transparent end-to-end sliceable Service Level Agreements (SLAs). This demo showcases an experimental prototype based on best of breed open source components (e.g., Ethereum, OVS, Neo4j, Ryu/OpenFlowv1.3, ARIA/TOSCA) illustrating blockchain Decentralized Application (DApp) functionalities for life cycle management of multi-administrative domain network services.
Jonathan Coignard, Eric Munsing, Jason MacDonald, Jonathan Mather
The increased penetration of Distributed Energy Resources (DERs) on the distribution network creates local challenges in balancing consumption and generation. To coordinate the roll-out and the operation of DERs, distribution-level energy markets have been proposed, but there are currently few tools for simulating the operation of DERs in these proposed markets. We present a framework which utilizes a grid co- simulation platform (Mosaik) to simulation DER operation, while simulating market clearing operations with a blockchain network (Ethereum). The use of blockchains, an emerging technology for decentralized computing and data storage, allows us to model secure decentralized execution of market clearing functions and payment processes. By unifying simulation of market clearing rules and the physical grid, we are able to ensure that economic incentives are aligned with physical constraints, helping facilitate the development of more effective distributed energy markets. We demonstrate the use of this new simulation platform on a small feeder, for which a market mechanism to incentivize DER integration is explored.
Bitcoin is a decentralized crypto-currency, which is based on the peer-to-peer network, and was introduced by Satoshi Nakamoto in 2008. Bitcoin transactions are written by using a scripting language. The hash value of a transaction’s script is used to identify the transaction over the network. In February 2014, a Bitcoin exchange company, Mt. Gox, claimed that they had lost hundreds of millions US dollars worth of Bitcoins in an attack known as transaction malleability. Although known about since 2011, this was the first known attack that resulted in a company loosing multi-millions of US dollars in Bitcoins. Our reason for writing this paper is to understand Bitcoin transaction malleability and to propose an efficient solution. Our solution is a softfork (i.e., it can be gradually implemented). Towards the end of the paper we present a detailed analysis of our scheme with respect to various transaction malleability-based attack scenarios to show that our simple solution can prevent future incidents involving transaction malleability from occurring. We compare our scheme with existing approaches and present an analysis regarding the computational cost and storage requirements of our proposed solution, which shows the feasibility of our proposed scheme.
The Distributed nature of Bitcoin introduces security issues that necessitate security-specific enhancements in Bitcoin protocol. Therefore, proposing a method of incorporating criteria check and verification process for miners to participate in the mining process and join the mining pool respective
Blockchain platforms, such as Ethereum, allow a set of actors to maintain a\nledger of transactions without relying on a central authority and to deploy\nscripts, called smart contracts, that are executed whenever certain\ntransactions occur. These features can be used as basic building blocks for\nexecuting collaborative business processes between mutually untrusting parties.\nHowever, implementing business processes using the low-level primitives\nprovided by blockchain platforms is cumbersome and error-prone. In contrast,\nestablished business process management systems, such as those based on the\nstandard Business Process Model and Notation (BPMN), provide convenient\nabstractions for rapid development of process-oriented applications. This\narticle demonstrates how to combine the advantages of a business process\nmanagement system with those of a blockchain platform. The article introduces a\nblockchain-based BPMN execution engine, namely Caterpillar. Like any BPMN\nexecution engine, Caterpillar supports the creation of instances of a process\nmodel and allows users to monitor the state of process instances and to execute\ntasks thereof. The specificity of Caterpillar is that the state of each process\ninstance is maintained on the (Ethereum) blockchain and the workflow routing is\nperformed by smart contracts generated by a BPMN-to-Solidity compiler. The\nCaterpillar compiler supports a large array of BPMN constructs, including\nsubprocesses, multi-instances activities and event handlers. The paper\ndescribes the architecture of Caterpillar, and the interfaces it provides to\nsupport the monitoring of process instances, the allocation and execution of\nwork items, and the execution of service tasks.\n
We propose a decentralized routing algorithm that can be implemented in Bitcoin Lightning Network. All nodes in the network contribute equally to path searching. The algorithm is inspired from ant path searching algorithms.
This thesis focuses on the integration of smart contracts into the Bazo Blockchain with the goal of creating a platform for decentralized applications. Smart contracts are programs that are stored on a blockchain and can be triggered by transactions. Smart contracts offer opportunities in automation and bring along advantages provided by blockchains such as immutability, public visibility of transactions and decentralization. As blockchains are trust-less protocols, it is guar- anteed that smart contracts are executed as intended. The integration of smart contracts was solved by implementing a virtual machine that executes the instructions sent by a transaction. This stack based virtual machine uses byte arrays as base type, which enables the virtual machine to deal with numbers of arbitrary length. Working with elements of arbitrary size requires taking the length of the elements into account, when calculating the gas cost, in addition to the base cost of the instruction type. Furthermore, the virtual machine was embedded within the mining application, which required to alter the blockchain protocol and the mining application. As a result, smart contracts can be deployed and transactions that call functions of smart contracts can be executed. Calling a smart contract function leads to the execution of the contract in the virtual machine and persisting the result in the blockchain. The Bazo Blockchain contin- ues to be a research project, this means it’s not ready for production use due to complex setup and handling. Follow-up theses could simplify the development of smart contracts for the Bazo Blockchain by creating a high-level programming language that can be compiled to Bazo virtual machine instructions.
Message digest algorithms are one of the underlying building blocks of\nblockchain platforms such as Ethereum. This paper analyses situations in which\nthe message digest collision resistance property can be exploited by attackers.\nTwo mitigations for possible attacks are described: longer message digest sizes\nmake attacks more difficult; and, including timeliness properties limits the\namount of time an attacker has to determine a hash collision.\n
Hashgraph is data structure and consensus algorithm that is fast, with a very high throughput and low consensus latency, secure because of the asynchronous byzantine fault tolerant and fair due to the fairness of access, ordering, and timestamps. These properties enable new decentralized applications such as a stock market, improved collaborative applications, games, and auctions. Hashgraph is a new consensus protocol that has garnered attention lately by being projected as a technology that will make blockchains obsolete. Hashgraph currently scales only in the number of transactions processed but does not scale with the number of nodes in the network. Hashgraph will face the same issues that other public blockchains are facing today and may not be able to maintain its security and performance. In fact, scalability is still an open problem for public blockchains.
David Vangulick, Bertrand Cornélusse, Damien Ernst
Energy communities and peer-to-peer energy exchangesare expected to play an important role in the energy transition. In this context, the blockchain approach can be employed to foster this decentralized energy market. In [1],we evaluated several designs that should allow a Distribution System Operator (DSO) to accept peer-to-peer energyexchanges supported by this technology. This acceptanceis based on criteria such as a strong link with the wholesale/retail market, the resilience of the consensus to approve a block, the accuracy, traceability, privacy and security of the proposed schemes. We concluded that proof-ofstake (PoS), where the choice of node that creates a block isbased on a measure of its wealth, is the only method to fulfill these requirements. In the present paper, we clarify theidentification and estimation of bidding models to ensurethat the PoS that we are developing is a correct responseto two major issues with the PoS methodology, namely theconcentration of wealth and the ”nothing to stake” issue.1
Distributed ledger technologies, such as blockchain systems, have in recent years emerged as promising platforms for machine-to-machine commerce and other forms of multi-stakeholder applications. However, despite the potential demonstrated by projects such as Bitcoin, Ethereum, and Hyperledger Fabric, the disk space typically required to host a copy of a ledger may be prohibitively large for many categories of devices. In this paper, we introduce an approach for reducing ledger size in blockchain systems, based on arbitrary pruning predicate functions, allowing each network participant to independently select and remove any already applied transactions. We also show that if only pruning certain ledger transactions, the ability to derive an unmodified state data structure from the remaining transactions is maintained. The approach is validated through a supply chain use case utilizing a modified version of Hyperledger Fabric, in which ledger size is reduced by about 84.49% via selective transaction pruning.
Even though blockchain is mostly popular for its cryptocurrency, smart contracts have become a very prominent blockchain application. Smart contracts are like classes that can be called by client applications outside the blockchain. Therefore it is possible to develop blockchain-oriented software (BOS) that implements part of the business logic in the blockchain by using smart contracts. Currently, there is no design standard to model BOS. Since modeling is an important part of designing a software, developers may struggle to plan their BOS. In this paper, we show three complementary modeling approaches based on well-known software engineering models and apply them to a BOS example. Our goal is to start the discussion on specialized blockchain modeling notations.
This review focuses on the evolution of cloud computing and distributed ledger technologies (blockchains) over the last decade. Cloud computing relies mainly on a conceptually centralized service provisioning model, while blockchain technologies originate from a peer-to-peer and a completely distributed approach. Still, noteworthy commonalities between both approaches are often overlooked by researchers. Therefore, to the best of the authors knowledge, this paper reviews both domains in parallel for the first time. We conclude that both approaches have advantages and disadvantages. The advantages of centralized service provisioning approaches are often the disadvantages of distributed ledger approaches and vice versa. It is obviously an interesting question whether both approaches could be combined in a way that the advantages can be added while the disadvantages could be avoided. We derive a software stack that could build the foundation unifying the best of these two worlds and that would avoid existing shortcomings like vendor lock-in, some security problems, and inherent platform dependencies.
Blockchain has received much attention in recent years. This immense popularity has raised a number of concerns, scalability of blockchain systems being a common one. In this paper, we seek to understand how Ethereum, a well-established blockchain system, would respond to sharding. Sharding is a prevalent technique to increase the scalability of distributed systems. To understand how sharding would affect Ethereum, we model Ethereum blockchain as a graph and evaluate five methods to partition the graph. We analyze the results using three metrics: the balance among shards, the number of transactions that would involve multiple shards, and the amount of data that would be relocated across shards upon a repartitioning of the system.
Proof-of-Stake systems randomly choose, on each round, one of the\nparticipants as a consensus leader that extends the chain with the next block\nsuch that the selection probability is proportional to the owned stake.\nHowever, distributed random number generation is notoriously difficult. Systems\nthat derive randomness from the previous blocks are completely insecure;\nsolutions that provide secure random selection are inefficient due to their\nhigh communication complexity; and approaches that balance security and\nperformance exhibit selection bias. When block creation is rewarded with new\nstake, even a minor bias can have a severe cumulative effect.\n In this paper, we propose Robust Round Robin, a new consensus scheme that\naddresses this selection problem. We create reliable long-term identities by\nbootstrapping from an existing infrastructure, such as Intel's SGX processors,\nor by mining them starting from an initial fair distribution. For leader\nselection we use a deterministic approach. On each round, we select a set of\nthe previously created identities as consensus leader candidates in round robin\nmanner. Because simple round-robin alone is vulnerable to attacks and offers\npoor liveness, we complement such deterministic selection policy with a\nlightweight endorsement mechanism that is an interactive protocol between the\nleader candidates and a small subset of other system participants. Our solution\nhas low good efficiency as it requires no expensive distributed randomness\ngeneration and it provides block creation fairness which is crucial in\ndeployments that reward it with new stake.\n
M. Harris Haseeb, K. Raja Sekhar, Y V. Spandana, M Syam
Block chain is a trust which can be best understood by the state machine replication, It is decentralized distributed ledger which is along all peers in the network connected through nodes over Internet. Every Node in the chain have equal stake and also the main factor is every node which have greater CPU cycles has a chance to operate node by spending those CPU cycles and also show Proof Of Work. Hence when the block chain is used in Business Models it loses its Private transactions and Confidential Contracts.
Holger Kinkelin, Valentin Hauner, Heiko Niedermayer, Georg Carle
Numerous IoT applications, like building automation or process control of\nindustrial sites, exist today. These applications inherently have a strong\nconnection to the physical world. Hence, IT security threats cannot only cause\nproblems like data leaks but also safety issues which might harm people.\nAttacks on IT systems are not only performed by outside attackers but also\ninsiders like administrators. For this reason, we present ongoing work on a\nconfiguration management system (CMS) that provides control over\nadministrators, restrains their rights, and enforces separation of concerns. We\nreach this goal by conducting a configuration management process that requires\nmulti-party authorization for critical configurations to achieve Byzantine\nfault tolerance against attacks and faults by administrators. Only after a\nconfiguration has been authorized by multiple experts, it is applied to the\ntargeted devices. For the whole configuration management process, our CMS\nguarantees accountability and traceability. Lastly, our system is\ntamper-resistant as we leverage Hyperledger Fabric, which provides a\ndistributed execution environment for our CMS and a blockchain-based\ndistributed ledger that we use to store the configurations. A beneficial side\neffect of this approach is that our CMS is also suitable to manage\nconfigurations for infrastructure shared across different organizations that do\nnot need to trust each other.\n
This paper provides the first comprehensive survey of methods for inserting arbitrary data into Bitcoin’s blockchain. Historical methods of data insertion are described, along with lesser-known techniques that are optimized for efficiency. Insertion methods are compared on the basis of efficiency, cost, convenience of data reconstruction, permanence, and potentially negative impact on the Bitcoin ecosystem.
IOTA is a revolutionary new, next generation public distributed ledger that utilizes a novel invention, called a “Tangle”, at its core. The Tangle is a new data structure based on a Directed Acyclic Graph (DAG). As such it has no Blocks, no Chain and also no Miners. Because of this radical new architecture, things in IOTA work quite differently compared to other Blockchains.
Holger Kinkelin, Valentin Hauner, Heiko Niedermayer, Georg Carle
Numerous IoT applications, like building automation or process control of industrial sites, exist today. These applications inherently have a strong connection to the physical world. Hence, IT security threats cannot only cause problems like data leaks but also safety issues which might harm people. Attacks on IT systems are not only performed by outside attackers but also insiders like administrators. For this reason, we present ongoing work on a Byzantine fault tolerant configuration management system (CMS) that provides control over administrators, restrains their rights, and enforces separation of concerns. We reach this goal by conducting a configuration management process that requires multi-party authorization for critical configurations to prevent individual malicious administrators from performing undesired actions. Only after a configuration has been authorized by multiple experts, it is applied to the targeted devices. For the whole configuration management process, our CMS guarantees accountability and traceability. Lastly, our system is tamper-resistant as we leverage Hyperledger Fabric, which provides a distributed execution environment for our CMS and a blockchain-based distributed ledger that we use to store the configurations. A beneficial side effect of this approach is that our CMS is also suitable to manage configurations for infrastructure shared across different organizations that do not need to trust each other.
Decentralized crypto-currencies based on the blockchain architecture\nunder-utilize available network bandwidth, making them unable to scale to\nthousands of transactions per second. We define the Blockclique architecture,\nthat addresses this limitation by sharding transactions in a block graph with a\nfixed number of threads. The architecture allows the creation of intrinsically\ncompatible blocks in parallel, where each block references one previous block\nof each thread. The consistency of the Blockclique protocol is formally\nestablished in presence of attackers. An experimental evaluation of the\narchitecture's performance in large realistic networks demonstrates an\nefficient use of available bandwidth and a throughput of thousands of\ntransactions per second.\n