"The LNCS journal Transactions on Computational Science" reflects recent developments in the field of Computational Science, conceiving the field not as a mere ancillary science, but rather as an innovative approach supporting many other scientific disciplines. The journal focuses on original high-quality research in the realm of computational science in parallel and distributed environments, encompassing the facilitating theoretical foundations and the applications of large-scale computations and massive data processing. It addresses researchers and practitioners in areas ranging from aerospace to biochemistry, from electronics to geosciences, from mathematics to software architecture, presenting verifiable computational methods, findings and solutions and enabling industrial users to apply techniques of leading-edge, large-scale, high performance computational methods. This issue focuses on the theme of security in computing, a topic of vital importance in the increasingly connected world of today. The 14 extensive papers selected for inclusion in this volume give an in-depth coverage of a number of hot topics in the field, presenting new architectures, novel hardware implementations, cryptographic algorithms and security protocols, and new tools and applications.