Crowdsourcing has been pursued as a way to leverage the power of the crowd for many different purposes in diverse sectors from collecting information, aggregating funds, and gathering employees to perform tasks of different sizes among other targets. Data integrity and nonrepudiation are of utmost importance in these systems and are currently not guaranteed. Blockchain technology has been proven to improve on these aspects. In this article, we investigate the benefits that the adoption of Blockchain technology can bring in crowdsourcing systems. To this end, we provide examples of real-life crowdsourcing use cases and explore the benefits of using Blockchain, mainly as a database.

As we transition into the era of Web 3.0, where decentralized information and user privacy are paramount, emerging technologies are reshaping the way in which personal data are managed. This paper focuses on decentralized identity management (DID) in the metaverse, particularly within the education sector, which has rapidly embraced digital tools for e-learning, especially since the COVID-19 pandemic. Technologies such as blockchain, artificial intelligence (AI), and virtual and augmented reality (VR/AR) are increasingly integrated into educational platforms, raising questions about privacy, security, and interoperability. This literature review examines the current landscape of DID in metaverse-based educational applications. Through a systematic methodology, relevant academic papers were identified, filtered, and analyzed based on four key criteria: standardization, interoperability, application scalability, and security/privacy considerations. The paper provides a comparative analysis of these papers to assess the maturity of DID implementations, highlight existing challenges, and suggest future research directions in the intersection of decentralized identity and educational metaverse applications.

The Internet of Things (IoT) continues to suffer from security issues, even after 20 years of technological evolution and continuing efforts. While the decentralization of the IoT seems to be a solution for improved resource management and scalability, most of the services remain centralized, exposing IoT systems to malicious attacks. As a result, this leads to functionality failures and endangers user and data integrity. Identity and Access Management (IAM) has the ability to provide defense against a great number of security threats. Additionally, blockchain is a technology which can natively support decentralization, as well as access and authorization management techniques, using the corresponding programmable logic and leveraging cryptographic mechanisms for privacy and security. Using standardized frameworks (e.g., Decentralized Identifiers and Verifiable Credentials), a blockchain-based access and authorization solution can present the basis for a uniform decentralized IAM framework for the IoT. To this end, this paper presents a proof-of-concept design and implementation of an IAM solution based on Solidity smart contracts, targeting two areas: firstly, supporting the fact that blockchain can seamlessly provide the basis for a decentralized IAM framework, while secondly (and most importantly) exploring the challenge of integrating within existing IoT systems, avoiding redesigning and redeveloping on behalf of IoT manufacturers.

OPTORER is a newly funded project targeting to enhance and support cultural activities within the region of Attica. OPTORER introduces a novel routing and exploration service in outdoor and indoor areas of touristic and cultural interest in the broad area of Attica. It offers a series of innovative routings across and towards areas of interest, targeting users experience optimization and promotion of underlying purposes. Safety and social wellbeing are prioritized for every tour. Making use of the smartphone device most end users possess, as well as wearable devices such as activity trackers in the form of bracelets/smartwatches that lately have gained broad adoption for self-monitoring activity and wellbeing, the project offers a complete solution developing the algorithms and the end user applications along with an orchestration platform responsible for the administration, operation and execution of the service producing and presenting to the end user results coming from the solution of complex optimization problems.