Middleware for Decentralization

Context: One of our fundamental focus of research is the design and development of algorithms and framework to enable decentralized operations in large scale cyber-physical systems. We note that a number of these systems require multiple entities and stakeholders to participate and as such the systems are vulnerable to data and operational disruptions, which are common in centralized architectures. These challenges have led to increasing focus on SCC platforms that provide participants the capability to not only exchange data and services in a decentralized and perhaps anonymous manner, but also provide them with the capability to preserve an immutable and auditable record of all transactions in the system. Such transactive platforms are actively being suggested for use in Healthcare, Smart Energy Systems, and Smart Transportation Systems. These platforms can provide support for privacy-preserving and anonymizing techniques, such as differential privacy, fully homomorphic encryption, and mixing. Further, the immutable nature of records and event chronology in these platforms provides high rigor and auditability. Lastly, the decentralized nature of these platforms ensures that any adversary needs to compromise a large number of node to take control of the system. Blockchains form a key component of these platforms because they enable participants to reach a consensus on any state variable in the system, without relying on a trusted third party or trusting each other. Distributed consensus not only solves the trust issue, but also provides fault-tolerance since consensus is always reached on the correct state as long as the number of faulty nodes is below a threshold. Further, blockchains also enable performing computation in a distributed and trustworthy manner in the form of smart contracts. However, while the distributed integrity of a blockchain ledger presents unique opportunities, it also introduces new assurance challenges that must be addressed before protocols and implementations can live up to their potential.

As such, one of the fundamental focus of our research is the use of Blockchain for decentralization of operation in large scale multistake holder cyber-physical systems. Examples of this type of system include smart cities, transactive energy, and IoT. The current form of these systems allows large scale stakeholders to participate, for example in the case of power systems bulk energy markets between power plants and power distribution companies, and in the case of IoT the various internet providers make agreements with each other to allow access to each other’s networks.

Background: Our work in multi-stakeholder systems has spanned the last 4 years. With the advent of blockchain based technology there was substantial interest in applying to not only financial systems but also enabling contracts between stakeholders. To explore this direction the Smart and Resilient Computing for Physical Environments Lab (SCOPE) has been working to explore these distributed contract based market systems to enable transactive energy as well as the outsourcing of compute tasks to nodes with surplus capacity. We are thankful to Siemens Corporate Technology and the National Science Foundation (NSF) for sponsoring our efforts.

Innovation: To confront issues of privacy, efficiency, and safety in MSCPS, we have developed a platform for transactive energy system microgrids3. The availability of distributed energy resources (DER) in communities have presented novel opportunities, as these resources are located closer to loads and can significantly reduce transmission losses and carbon emissions, relative to traditional power sources. However, their intermittent and variable nature often results in spikes in the overall demand on distribution system operators (DSO). To manage these challenges, there has been a surge of interest in building decentralized control schemes, where a pool of DERs combined with energy storage devices can exchange energy locally to smooth fluctuations in net demand. Building a decentralized market for transactive microgrids is challenging because even though a decentralized system provides resilience, it also must satisfy the requirements of privacy, efficiency, safety, and security, which are often in conflict with each other. As such, existing implementations of decentralized markets often focus on resilience and safety but compromise on privacy.

Research Products: Our platform, called TRANSAX, enables participants to trade in an energy futures market, which improves efficiency by finding feasible matches for energy trades, enabling DSOs to plan their energy needs better. TRANSAX provides privacy to participants by anonymizing their trading activity using a distributed mixing service, while also enforcing constraints that limit trading activity based on safety requirements, such as keeping planned energy flow below line capacity. We show that TRANSAX can satisfy the seemingly conflicting requirements of efficiency, safety, and privacy. We also provide an analysis of how much trading efficiency is lost. Trading efficiency is improved through the problem formulation which accounts for temporal flexibility, and system efficiency is improved using a hybrid-solver architecture. We also describe a testbed to run experiments and demonstrate its performance using simulation results. To demonstrate the feasibility of our platform, we perform experiments with dozens of embedded devices and energy production and consumption profiles from a real dataset.

In the context of TES we developed SolidWorx, a platform for enabling participants to trade in futures market. To improve efficiency we reduce the amount of computation that is performed using the smart contract by implementing a hybrid-solver pattern which relies on off-chain solvers to match the offers posted to the system. We only use the smart contract to verify that the solutions are valid.

To enable trusted computations between mistrusting parties in the edge-cloud environment while minimizing the additional computation overhead, we have developed a platform for outsourcing computations. The existing efforts to construct such a platform, particularly those using blockchain, focus on ensuring global consensus on the results of the computation, but there are many cases where this is not required. Our platform, called MODiCuM, does not execute any of the outsourced computation as part of the smart contract, but instead uses the contract to hold the participants accountable. This effectively replaces the trusted third party required for general trusted two-party computation with the distributed ledger and smart contract.