Davor Vinko

Accredited laboratories participating in Proficiency Testing (PT) and Interlaboratory Comparison (ILC) typically submit measurement results (and associated uncertainties) to an organizer for performance evaluation using statistics such as the z-score and the En value. This requirement can undermine confidentiality when the disclosed plaintext values reveal commercially sensitive methods or client-related information. This paper proposes a secure-by-design PT/ILC workflow based on fully homomorphic encryption (FHE), enabling the required scoring computations to be executed directly on ciphertexts. Using the CKKS scheme (Microsoft SEAL), the organizer distributes encrypted assigned values and a public/evaluation key set; each participant locally encrypts pre-processed measurement data, evaluates encrypted z-score and En value, and returns only encrypted performance metrics. The organizer decrypts the metrics without receiving the ciphertexts of participants’ raw measurement values. We quantify feasibility via execution time, run-to-run variability across fresh key generations (coefficient of variation), and relative calculation error versus plaintext scoring. On commodity hardware, end-to-end score computation takes 1 to 8 s, the coefficient of variation can be reduced below 1e⁻¹⁰, and the relative error remains below 1e⁻⁶, indicating practical deployability and numerical stability for PT/ILC decision-making. Given that PT/ILC reporting cycles are typically on the order of days to weeks, a per-participant computation time of seconds is operationally negligible, while the observed coefficient of variation and relative error indicate that the CKKS approximation and key-dependent variability are far below typical decision thresholds used for pass/fail classification.

Precision agriculture will continue to heavily rely on data-driven models to enable more intensive crop monitoring and data-driven decisions. The available remote sensing techniques, particularly those based on multispectral Sentinel-2 data, still have major shortcomings due to cloud cover, low temporal resolution, and time lags in data availability. To address these shortcomings, this paper proposes a hybrid approach that combines Sentinel-2 satellite data with real-time data generated by low-cost ground-based single-pixel detectors (SPDs), such as the AS7263. This hybrid approach addresses key shortcomings in existing agricultural monitoring systems and offers a cost-effective, scalable solution for real-time monitoring and prediction of end-of-season yield, moisture, and plant height using simple PLRS models implemented directly in SPDs with an energy-efficient algorithm for deployment on the STM32G030 microcontroller.

This paper reviews hardware-based protection methods for electronic devices, encompassing scientific publications and published patents. This review covers insights from the scientific community and innovative solutions patented in the industry. By combining these two sources, this paper offers a comprehensive and holistic review of electronic device security. Electronic devices are integral to modern life, but their widespread use invites security threats, both digital and physical. This paper reviews hardware-based protection methods against invasive and non-invasive attacks, emphasizing the importance of a dual approach through hardware design. Invasive attacks involve physical tampering, and we explore anti-tampering techniques such as conductive meshes, sensors and physically unclonable functions (PUFs). Non-invasive, side-channel attacks encompass various attack vectors, focusing on electromagnetic analysis. To counter these attacks, we analyze techniques like reducing and masking electromagnetic radiation. This paper bridges the gap between invasive and non-invasive attack mitigation. It underscores the necessity of a multifaceted approach to safeguard electronic devices in an interconnected world, preserving their reliability and functionality.

Blockchain-based applications necessitate the authentication of connected devices if they are employed as blockchain oracles. Alongside identity authentication, it is crucial to ensure resistance against tampering, including safeguarding against unauthorized alterations and protection against device counterfeiting or cloning. However, attaining these functionalities becomes more challenging when dealing with resource-constrained devices like low-cost IoT devices. The resources of IoT devices depend on the capabilities of the microcontroller they are built around. Low-cost devices utilize microcontrollers with limited computational power, small memory capacity, and lack advanced features such as a dedicated secure cryptographic chip. This paper proposes a method employing a Physical Unclonable Function (PUF) to authenticate identity and tamper resistance in IoT devices. The suggested PUF relies on a microcontroller’s internal pull-up resistor values and, in conjunction with the microcontroller’s built-in analog comparator, can also be utilized for device self-checking. A main contribution of this paper is the proposed PUF method which calculates the PUF value as the average value of many single PUF measurements, resulting in a significant increase in accuracy. The proposed PUF has been implemented successfully in a low-cost microcontroller device. Test results demonstrate that the device, specifically the microcontroller chip, can be identified with high accuracy (99.98%), and the proposed PUF method exhibits resistance against probing attempts.

Digital transformation of metrology is a holistic process that was started formally by the Joint Statement of Intent “On the digital transformation in the international scientific and quality infrastructure” signed by major metrology organisations in March 2022. With the digital transformation of metrology in motion, the questions of a seamless transition to digital representation while ensuring adherence to all the requirements of digital representation and maintaining a sustainable framework for future operations are just some of the challenges faced. To tackle these challenges, also within the concept of “more electrical world” (MEW), one technology is demonstrating high potential applicability as a possible candidate solution—blockchain technology, with its critical underlying properties (e.g., immutability, decentralisation, etc.) being fully compliant with the requirements of digital representation in metrology. Accordingly, this paper presents a blockchain-based concept for the digital transformation of the traceability pyramid for electrical energy measurement. The concept is developed in accordance with the goals of the Metroracle project. Based on the analyzed and presented state-of-the-art, the main contribution of the paper is the comprehensiveness of the concept, which encompasses the whole pyramid and describes all relevant processes and responsibilities of all stakeholders: measurement instrument (MI) owners, certificate issuers (National Accreditation Body (NAB), National laboratory (NL), Reference laboratory (RL)), MI manufacturers/developers, MI installers. The transformed pyramid is defined by Croatian metrology laws and regulations, but with smaller adjustments, it is applicable to other EU countries as well, and also to the traceability of other physical quantities, i.e., not to electrical energy only. Possible legal and technical issues are identified (amount of data, machine-readable standards and regulations, ensuring limited access, legal relevance of digital signature) and corresponding solutions presented, as well as further steps in our research and development within the Metroracle project.

With advances in Information and Communication Technologies (ICT) in convergence with blockchain technology, cities have been given the opportunity to improve their services, efficiently use resources, and, thus, become Smart Cities. The main properties of blockchain technology like decentralization, immutability, transparency, consensus, and robustness are qualities needed for Smart City. In this paper, we propose a digitalization strategy for the City of Osijek. Smart City digitalization strategy aims to solve problems of emerging urbanization, improve administration by reducing energy and water consumption, carbon emissions, pollution, and city waste management. To develop an information system based on blockchain technology, the administration structure and the current state of information systems are analyzed, and new solutions are presented.

In magnetically coupled resonant wireless power transfer (MCR-WPT) systems, the nonhomogeneous magnetic field of the transmitting coil can lead to frequency splitting phenomena and lower efficiency. In this paper, a 3D transmitting coil (TX) with a homogeneous magnetic field distribution is proposed. The proposed coil structure consists of two layers with different numbers of turns per layer, i.e., with different current distributions. To achieve a homogeneous magnetic field distribution with a high magnetic field value and a low profile of the 3D coil structure, the optimal layer placement and current distribution were optimized using a genetic algorithm (GA). The prototype of the optimized coil was fabricated, and its magnetic field distribution was measured. The measurement results agreed more than 95% with the simulation results. The measured homogeneous area was at least 12.5% larger than reported in the literature. By using a different current distribution, the profile of the 3D coil structure was successfully reduced by 29% and the average magnetic field value was increased by 25% compared to our previous work.

Conventional magnetically coupled resonant wireless power transfer systems are faced with resonant frequency splitting phenomena and impedance mismatch when a receiving coil is placed at misaligned position. These problems can be avoided by using uniform magnetic field distribution at receiving plane. In this paper, a novel 3D transmitting coil structure with improved uniform magnetic field distribution is proposed based on a developed optimization method. The goal is to maximize the average magnetic field strength and uniform magnetic field section of the receiving plane. Hence, figures of merit (FoM₁ and FoM₂) are introduced and defined as product of average magnetic field strength and length or surface along which uniform magnetic field is generated, respectively. The validity of the optimization method is verified through laboratory measurements performed on the fabricated coils driven by signal generator at operating frequency of 150kHz. Depending on the allowed ripple value and predefined coil proportions, the proposed transmitting coil structure gives the uniform magnetic field distribution across 50 to 90 of the receiving plane.