The increasing demand for trusted and verifiable digital microcredentials in education and professional development has created new challenges related to data integrity, decentralization, and service scalability. Although blockchain technology has been widely proposed as a potential solution, existing approaches often lack operational rigor, security formalization, and alignment with service-oriented computing paradigms. This paper introduces Skillchain, a blockchain-based microcredential management platform implemented on Ethereum, designed as a secure, decentralized trust service. We present a full-stack architecture that incorporates a hybrid network model and a Proof-of-Authority consensus mechanism, enabling efficient issuance, revocation, and validation of digital microcredentials. A key contribution of this work is the integration of smart contract–based access control and on-chain governance, providing trusted organizations with structured authorization workflows. The proposed platform is evaluated through a comprehensive set of performance and security experiments, which demonstrate scalability to thousands of concurrent transactions and resilience against misconfigured node vulnerabilities. A formal threat model is developed, and countermeasures are implemented at the protocol and smart contract levels. Comparative analysis with centralized and federated models is provided, highlighting trade-offs in latency, transparency, and trust distribution. This study advances the state-of-the-art in blockchain-enabled service computing by offering a reproducible, extensible service architecture for secure credential management. The findings highlight the platform's potential for integration with interoperable credential ecosystems and contribute to advancing decentralized service computing for trusted digital credentials.

As civilization advances, decision-making problems become increasingly complex, posing significant challenges in deriving optimal solutions. The field of multi-criteria decision analysis (MCDA) has evolved to address these complexities; however, single-solution approaches are often inadequate in multi-decision-maker scenarios, necessitating group decision-making methods. This study proposes an alternative compromise solution for evaluating electric car performance, examining various compromise approaches, including voting methods like Borda and Copeland counts, and more advanced techniques such as Iterative Compromise Ranking Analysis (ICRA), Improved Borda, HQ compromise, Dominance-directed graph, and Rank position methods. These methods were assessed using two ranking correlation coefficients to evaluate their effectiveness in multi-decision-maker scenarios. Results indicate that while minor differences in rankings were observed based on the chosen compromise method, these differences could influence decision-making outcomes. The analysis highlights the importance of selecting methods that align with specific needs and expectations. Future research should focus on simulation-based studies to better understand the characteristics of each method and apply these methods to real-world case studies to determine their suitability in various contexts.

The intensive development and growth in the popularity of mobile cloud computing services bring a critical need to introduce new solutions that increase the level of cloud and users security. One of the critical issues in highly distributed computational systems is a task scheduling process. This process may be exposed to many external and internal security threats, like task injection, machine failure or generation of incorrect schedule. These problems are especially important in mobile environments. It can be even more complicated if we take into consideration the personalization of the services offered. Recently, blockchain has been gaining rapidly in popularity, combining high efficiency with applications in distributed and highly personalized computational environments. In this paper, we developed and described a novel model for security-aware task scheduling in cloud computing based on blockchain technology. Unlike other blockchain-based solutions, the proposed model uses Proof of Stake, which does not have high requirements for computing power. A series of conducted experiments confirmed the high efficiency of the proposed model.

The problem of efficient use of computer resources is the actual challenge for many years. Huge progress in the hardware development has left behind the development of software techniques. One of the most popular solutions for this problem is the idea of virtualization, which a natural continuation is cloud computing. Cloud computing is an innovative concept, where the resources are virtualized, dynamically extended and provided as highly personalized services. In this paper, we present a short analysis of open-source cloud technology OpenStack. We described OpenStack architecture, requirements, setup process, and related problems. We also conducted a thorough analysis of resource utility both at full load and without. In our experiments we have analyzed the performance depending on the allocation of virtual resources. Through our work we pointed out aspects which deserve attention by choosing an OpenStack platform. Additionally, we draw attention to the burden on the use of technologies such as OpenStack cloud.