Digital credentials enable users to perform secure interactions by proving either their identity or that they posses certain attributes. Special care is taken to protect these credentials and their associated private keys during transaction time. However, protection of these items outside of the transaction is often delegated to a secure credential repository. A mobile environment creates significant challenges for secure repositories. We examine these challenges with respect to existing repository practices and produce a set of requirements that a repository must meet in order to cope with the harshness of a mobile environment. We also present the design and implementation of Thor (The hybrid online repository), a system that fulfills these requirements. Thor leverages preexisting local and remote repositories and enhances their usability and security through centralized management, credential context subsets, and credential identifier obfuscation.

In mobile and wireless networks, data broadcasting for popular data items enables the efficient utilization of the limited wireless bandwidth. However, efficient data scheduling schemes are needed to fully exploit the benefits of data broadcasting. Towards this goal, several broadcast scheduling policies have been proposed. These existing schemes have mostly focused on either minimizing response time, or drop rate, when requests are associated with hard deadlines. The inherent inaccuracy of hard deadlines in a dynamic mobile environment motivated us to use Service Level Agreements (SLAs) where a user specifies the utility of data as a function of its arrival time. Moreover, SLAs provide the mobile user with an already familiar quality of service specification from wired environments. Hence, in this dissertation, we propose SAAB, an SLA-aware adaptive data broadcast scheduling policy for maximizing the system utility under SLA-based performance measures. To achieve this goal, SAAB considers both the characteristics of disseminated data objects as well as the SLAs associated with them. Additionally, SAAB automatically adjusts to the system workload conditions which enables it to constantly outperform existing broadcast scheduling policies.

In mobile and wireless networks, data broadcasting for popular data items enables the efficient utilization of the limited wireless bandwidth. However, efficient data scheduling schemes are needed to fully exploit the benefits of data broadcasting. Towards this goal, several broadcast scheduling policies have been proposed. These existing schemes have mostly focused on either minimizing response time, or drop rate, when requests are associated with hard deadlines. The inherent inaccuracy of hard deadlines in a dynamic mobile environment motivated us to use Service Level Agreements (SLAs) where a user specifies the utility of data as a function of its arrival time. Moreover, SLAs provide the mobile user with an already familiar quality of service specification from wired environments. Hence, in this dissertation, we propose SAAB, an SLA-aware adaptive data broadcast scheduling policy for maximizing the system utility under SLA-based performance measures. To achieve this goal, SAAB considers both the characteristics of disseminated data objects as well as the SLAs associated with them. Additionally, SAAB automatically adjusts to the system workload conditions which enables it to constantly outperform existing broadcast scheduling policies.

MATULA, Kamil. Information Seeking in the Mobile Environment. Praha: Univerzita Karlova, Filozofická fakulta, Ústav informačních studií a knihovnictví, 2021. Ph.D. Thesis. Supervisor PhDr. et Bc. Jindra Planková, Ph.D. Abstract The dissertation thesis deals with information seeking in mobile environment using smartphone. For this purpose, a qualitative research is conducted, devided into two consecutive research activities. In the first activity are used semistructured interviews to collect the data and the grounded theory is used for data analysis. In the second activity are used methods "thinking aloud" and practical information seeking based on model scenarios. Results of the second research activity are evaluated by thematic analysis and task analysis. The findings have broadenend and deepend the state of current knowledge concerning the information seeking in the mobile environment. We consider exploration of limiting factors that affect information seeking in mobile environment as one of the most beneficial result as well as discovery of two extreme styles of information seeking in mobile environment. Keywords Information Behaviour; Information Seeking; Information Retrieval; Mobile En- vironment; Mobile Information and Communication Technologies; Qualitative Research; Semistructured Interview; Thinking...