Information and Communications Technology (ICT) is a pillar of today's society. In the last decades we have progressed to a point where most of our critical infrastructure is managed using highly complex distributed systems, with large numbers of heterogeneous computing machines. Cybersecurity and security protection in ICT however, are lagging behind, as it is in general very costly to achieve. This delay in securing ICT infrastructures can have dire consequences in practice, as has already been shown by recent security incidents targeting critical sectors of society, including energy and water management infrastructures, healthcare organisations, and confidential data storage. Improving the security, dependability, and efficiency of ICT systems for critical society sectors has been the main research focus of the author since the start of his scientific career. In the last five years he has focused mostly on secure distributed systems, in particular how to efficiently store, share, and search data with strong privacy, integrity, and availability guarantees. In this scientific area, he has contributed by proposing new protocols for securely storing and querying data in distributed NoSQL databases, confidential blockchains, and cloud data repositories. These contributions have paved the way for building more secure distributed systems that can support different applications scenarios. Google Scholar Profile: https://scholar.google.pt/citations?user=M_bf0BIAAAAJ&hl=en