The integrity and traceability of digital photographic evidence represent a critical factor during forensic investigations, especially when this evidence undergoes technical transformations, such as cropping or resolution enhancement. Ensuring that these modifications remain transparent, verifiable, and attributable is essential to maintaining the value of the evidence during an investigation. To meet these requirements, existing systems typically rely on blockchain-based implementations within permissioned networks or provide only limited support for image transformations. As a result, they often lack the flexibility and transparency required for open or decentralized forensic scenarios. In this paper, we propose an endorsement-based image forensics system that leverages public blockchain to record the lifecycle and verify the authenticity of images. Our system employs hybrid encryption to provide confidentiality of uploaded images while simultaneously ensuring that they remain auditable and non-repudiable. The system supports different trust models and enables users to assess the trustworthiness of an image’s provenance data directly and indirectly. Direct trust is achieved by validating an image transformation through reproducible functions or zero-knowledge proofs; indirect trust is enabled through publicly recorded endorsements. Our design achieves low gas costs and provides confidentiality, verifiability, and traceability guarantees, improving upon previous approaches without relying on permissioned infrastructures.

In recent years, the implementation of vehicle restricted areas (e.g., Low Emission Zones or Congestion Charge Zones) has proven effective in addressing urban traffic congestion and environmental pollution. Traditionally, these zones have been enforced using the highly centralized and infrastructure-expensive panoptic model. However, recent advancements in smart vehicle technology have enabled a shift towards decentralized, infrastructure-free approaches such as the lateral surveillance model. While offering significant advantages, this novel model also presents relevant security and privacy challenges, including potential misuse and widespread surveillance. This paper introduces a novel autonomous, decentralized, and infrastructure-free solution aligned with the lateral surveillance model. Leveraging Blockchain technology and privacy preservation measures, the system ensures user anonymity during fee pricing and payment processes, and it is capable of detecting and sanctioning dishonest drivers. To assess the applicability of the new scheme in real-world scenarios, it was implemented and tested in controlled environments as well as a low-traffic street. The evaluation included an assessment of the gas costs associated with the smart contracts and a detailed scalability analysis. The theoretical and experimental results demonstrate the feasibility of the proposed solution.

Low Emission Zones (LEZ)s are areas where access restrictions to polluting vehicles are enforced. These infrastructures have become a main mechanism in large cities to deal with urban traffic and environmental pollution. A main problem of practical LEZs is that they generally depend on a camera network that identifies users and jeopardizes their privacy. In the literature, there are some privacy-preserving works that rely on camera-free approaches; however, they still suffer from a major issue: they depend on centralized entities to manage the vehicles’ accesses/departures and their corresponding fee payment. Those centralized entities represent a critical single point of failure in the system, endangering its security and availability. In order to address this situation, this paper proposes a new scheme that decentralizes the LEZ management, dealing with vehicle accesses as blockchain transactions, and pricing and charging them using smart contracts. In order to validate the deployability of the new scheme in real scenarios, it has been implemented and tested in both a controlled environment and a low-traffic street. The evaluation of the smart contracts’ costs in terms of gas has been included in the performed tests. The results obtained are satisfactory and show the feasibility of the new proposal.

This work presents a complex privacy-preserving solution based on attribute-based credentials and smart contract techniques for emerging parking services in city zones. Our system provides the full set of privacy-enhancing features such as anonymity, untraceability, and unlinkability of user parking registrations. Thanks to that it prevents the city and service providers from profiling and tracking the users (e.g., their movement). Furthermore, we involved smart contracts and the underlying decentralized Blockchain technology in payment and verification phases to prevent the presence of a single point of failure in those processes which can endanger the system’s security and availability. We provide the full cryptographic specification of the system, its security analysis, and the implementation results in this paper.

The traffic control system proposed in this article has as its main objectives the security, the reliability and the anonymity of the vehicle access to traffic-restricted urban zones. The aim of these zones is to reduce atmospheric pollution in urban centers. The presented approach makes use of smartphones as a communication device between the user and the virtual barrier, which acts as electronic validator and controls the access to the restricted zone. The access is fast (it does not require the complete stop of the vehicle) and is less invasive when compared to existing systems that are based on video camera recording. This is a versatile and cost-efficient system that can be adapted to other access-controlled urban settings: parking lots, sport event access zones, festivals, etc.