Valerio Mandarino

Authentication is essential to hold users accountable across online services. Conventional authentication systems rely on centralized architectures or third-party identity providers, which, however, introduce single points of failure, privacy concerns, and limited user autonomy. Conversely, fully decentralized authentication frameworks often struggle to provide reliable identity attestation mechanisms. This makes them vulnerable to Sybil attacks and self-asserted claims, while limiting their interoperability with trust-based systems. This paper presents dAuth, a hybrid blockchain-based authentication architecture based on Ethereum smart contracts to provide cryptographic tokens that enable authentication to services. These tokens, anchored to the smart contract, are derived by users from institutionally certified base credentials issued by an accredited verifying authority and enable authentication to services without further involvement of the authority. Each token is cryptographically bound to a specific service, constrained in scope and duration, and verifiable off-chain through data and cryptographic commitments provided by the user. No plaintext personal information is published on-chain: identity attributes are committed as cryptographic digests, which anchor certified identity data on-chain while keeping the underlying personal information private and auditable. This design removes the verifying authority from the authentication process, as all authentication steps are assisted by the user-controlled smart contract. The verifying authority’s role is limited to initial identity certification and exceptional update procedures. The result is a privacy-preserving and verifiable hybrid authentication framework that leverages the cryptographic security properties of the underlying blockchain infrastructure and inherits its scalability characteristics. The proposed design has been implemented and experimentally evaluated on the Ethereum platform, addressing public blockchain-specific challenges such as scalability constraints and transaction costs to ensure practical deployment.

Blockchain technology offers unique features, such as transparency, the immutability of data, and the capacity to establish trust without a central authority. Such characteristics can be leveraged to support the collaboration among several different software systems operating within the healthcare ecosystem, while ensuring data integrity and make electronic health records (EHRs) more easily accessible. To provide a solution based on blockchain technology, this paper has evaluated the main issues that arise when large amounts of data are expected, i.e., mainly cost and performance. A balanced approach that maximizes the benefits and mitigates the constraints of the blockchain has been designed. The proposed decentralized application (dApp) architecture employs a hybrid storage strategy that involves storing medical records locally, on users’ devices, while utilizing blockchain to manage an index of these data. The dApp clients facilitate interactions among participants, leveraging a smart contract to enable patients to set authorization policies, thereby ensuring that only designated healthcare providers and authorized entities have access to specific medical records. The blockchain data-immutability property is used to validate data stored externally. This solution significantly reduces the costs related to the utilization of the blockchain, while retaining its advantages, and improves performance, since the majority of data are available off-chain.

The increased penetration of Distributed Energy Resources (DERs) in electricity markets has given rise to a new category of energy players, called Aggregators, whose role is to ensure fair remuneration for energy supplied by DERs, and support the smooth feeding of the intermittent energy produced into the distribution network. This paper presents a software solution, described as a design pattern, that governs the interaction between an Aggregator and DERs, leveraging blockchain technology to achieve a higher degree of decentralization, data integrity and security, through a properly designed, blockchain-based, smart contract. Thus, the proposed solution reduces the reliance on intermediaries acting as authorities, while affording transparency, efficiency and trust to the energy exchange process. Thanks to the underlying blockchain properties, generated events are easily observable and cannot be forged or altered. However, blockchain technology has inherent drawbacks, i.e., mainly the cost of storage and execution, hence our solution provides additional strategies for limiting blockchain usage, without undermining its strengths. Moreover, the design of our smart contract takes care of orchestrating the players, and copes with their potential mutual disagreements, which could arise from different measures of energy, providing an automatic decision process to resolve such disputes. The overall approach results in lower fees for running smart contacts supporting energy players and in a greater degree of fairness assurance.