Publications by Stefano De Angelis
One of the main trends in the evolution of smart grids is transactive energy, where distributed e... more One of the main trends in the evolution of smart grids is transactive energy, where distributed energy resources, e.g. smart meters, develop towards Internet-of-Things (IoT) devices enabling prosumers to trade energy directly among each other, without the need of involving any centralised third party. The expected advantages in terms of cost-effectiveness would be significant, indeed technical solutions are being investigated and large-scale deployment are planned by major utilities companies. However, introducing transactive energy in the smart grid entails new security threats, such as forging energy transactions.{\ensuremath{<}}br/{\ensuremath{>}}This paper introduces an infrastructure to support reliable and cost-effective transactive energy, based on blockchain and smart contracts, where functionalities are implemented as fully decentralised applications. Energy transactions are stored in the blockchain, whose high replication level ensures stronger guarantees against tampering. Energy auctions are carried out according to transparent rules implemented as smart contracts, hence visible to all involved actors. Threats deriving from known vulnerabilities of smart meters are mitigated by temporarily keeping out exposed prosumers and updating their devices as soon as security patches become available.
Permissioned blockchains are arising as a solution to federate companies prompting accountable in... more Permissioned blockchains are arising as a solution to federate companies prompting accountable interactions. A variety of consensus algorithms for such blockchains have been proposed, each of which has different benefits and drawbacks. Proof-of-Authority (PoA) is a new family of Byzantine fault-tolerant (BFT) consensus algorithms largely used in practice to ensure better performance than traditional Practical Byzantine Fault Tolerance (PBFT). However, the lack of adequate analysis of PoA hinders any cautious evaluation of their effectiveness in real-world permissioned blockchains deployed over the Internet, hence on an eventually synchronous network experimenting Byzantine nodes.
Thesis Chapters by Stefano De Angelis
Blockchain is a novel technology that is rising a lot of interest in the industrial and re- searc... more Blockchain is a novel technology that is rising a lot of interest in the industrial and re- search sectors because its properties of decentralisation, immutability and data integrity. Initially, the underlying consensus mechanism has been designed for permissionless block- chain on trustless network model through the proof-of-work, i.e. a mathematical challenge which requires high computational power. This solution suffers of poor performances, hence alternative consensus algorithms as the proof-of-stake have been proposed.
Conversely, for permissioned blockchain, where participants are known and authenti- cated, variants of distributed consensus algorithms have been employed. However, most of them comes out without formal expression of security analysis and trust assumptions because the absence of an established knowledge. Therefore the lack of adequate analysis on these algorithms hinders any cautious evaluation of their effectiveness in a real-world setting where systems are deployed over trustless networks, i.e. Internet.
In this thesis we analyse security and performances of permissioned blockchain. Thus we design a general model for such a scenario in a way to propose a general benchmark for the experimental evaluations. This work brings two main contributions.
The first contribution concern the analysis of Proof-of-Authority, a Byzantine Fault- Tolerant consensus protocol. We compare two of the main algorithms, named Aura and Clique, with respect the well-established Practical Byzantine Fault-Tolerant, in terms of se- curity and performances. We refer the CAP theorem for the consistency, availability and partition tolerance guarantees and we describe a possible attack scenario in which one of the algorithms loses consistency. The analysis advocates that Proof-of-Authority for permissioned blockchains deployed over WANs experimenting Byzantine nodes, do not provide adequate consistency guarantees for scenarios where data integrity is essential. We claim that actually the Practical Byzantine Fault-Tolerant can fit better for permis- sioned blockchain, despite a limited loss in terms of performance.
The second contribution is the realisation of a benchmark for practical evaluations. We design a general model for permissioned blockchain under which benchmarking perfor- mances and security guarantees. However, because no experiment can verify all the pos- sible security issues permitted by the model, we prototype an adversarial model which simulate three attacks, feasible for a blockchain system. We then integrate this attacker model in a real blockchain client to evaluate the resiliency of the system and how much the attacks impact performances and security guarantees.
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Publications by Stefano De Angelis
Thesis Chapters by Stefano De Angelis
Conversely, for permissioned blockchain, where participants are known and authenti- cated, variants of distributed consensus algorithms have been employed. However, most of them comes out without formal expression of security analysis and trust assumptions because the absence of an established knowledge. Therefore the lack of adequate analysis on these algorithms hinders any cautious evaluation of their effectiveness in a real-world setting where systems are deployed over trustless networks, i.e. Internet.
In this thesis we analyse security and performances of permissioned blockchain. Thus we design a general model for such a scenario in a way to propose a general benchmark for the experimental evaluations. This work brings two main contributions.
The first contribution concern the analysis of Proof-of-Authority, a Byzantine Fault- Tolerant consensus protocol. We compare two of the main algorithms, named Aura and Clique, with respect the well-established Practical Byzantine Fault-Tolerant, in terms of se- curity and performances. We refer the CAP theorem for the consistency, availability and partition tolerance guarantees and we describe a possible attack scenario in which one of the algorithms loses consistency. The analysis advocates that Proof-of-Authority for permissioned blockchains deployed over WANs experimenting Byzantine nodes, do not provide adequate consistency guarantees for scenarios where data integrity is essential. We claim that actually the Practical Byzantine Fault-Tolerant can fit better for permis- sioned blockchain, despite a limited loss in terms of performance.
The second contribution is the realisation of a benchmark for practical evaluations. We design a general model for permissioned blockchain under which benchmarking perfor- mances and security guarantees. However, because no experiment can verify all the pos- sible security issues permitted by the model, we prototype an adversarial model which simulate three attacks, feasible for a blockchain system. We then integrate this attacker model in a real blockchain client to evaluate the resiliency of the system and how much the attacks impact performances and security guarantees.
Conversely, for permissioned blockchain, where participants are known and authenti- cated, variants of distributed consensus algorithms have been employed. However, most of them comes out without formal expression of security analysis and trust assumptions because the absence of an established knowledge. Therefore the lack of adequate analysis on these algorithms hinders any cautious evaluation of their effectiveness in a real-world setting where systems are deployed over trustless networks, i.e. Internet.
In this thesis we analyse security and performances of permissioned blockchain. Thus we design a general model for such a scenario in a way to propose a general benchmark for the experimental evaluations. This work brings two main contributions.
The first contribution concern the analysis of Proof-of-Authority, a Byzantine Fault- Tolerant consensus protocol. We compare two of the main algorithms, named Aura and Clique, with respect the well-established Practical Byzantine Fault-Tolerant, in terms of se- curity and performances. We refer the CAP theorem for the consistency, availability and partition tolerance guarantees and we describe a possible attack scenario in which one of the algorithms loses consistency. The analysis advocates that Proof-of-Authority for permissioned blockchains deployed over WANs experimenting Byzantine nodes, do not provide adequate consistency guarantees for scenarios where data integrity is essential. We claim that actually the Practical Byzantine Fault-Tolerant can fit better for permis- sioned blockchain, despite a limited loss in terms of performance.
The second contribution is the realisation of a benchmark for practical evaluations. We design a general model for permissioned blockchain under which benchmarking perfor- mances and security guarantees. However, because no experiment can verify all the pos- sible security issues permitted by the model, we prototype an adversarial model which simulate three attacks, feasible for a blockchain system. We then integrate this attacker model in a real blockchain client to evaluate the resiliency of the system and how much the attacks impact performances and security guarantees.