Traditional security policies largely focus on access control requirements, which specify who can access what under what circumstances. Besides access control requirements, the availability of services in many applications often further imposes obligation requirements, which specify what actions have to be taken by a subject in the future as a condition of getting certain privileges at present. However, it is not clear yet what the implications of obligation policies are concerning the security goals of a system.In this paper, we propose a formal metamodel that captures the key aspects of a system that are relevant to obligation management. We formally investigate the interpretation of security policies from the perspective of obligations, and define secure system states based on the concept of accountability. We also study the complexity of checking a state's accountability under different assumptions about a system.

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Gamification of education is still evolving. It lacks systematic studies assessing its effect in different learning contexts. Creating gamified courses is still difficult, since there is a lack of sufficient understanding of how to gamify learning and appropriate software support is missing. As a response to these challenges, we developed OneUp  ̶ a customizable platform aimed at facilitating the process of gamifying academic courses and enabling contextual studies on educational gamification. In this paper we rationalize our approach to building OneUp and present the underlying principles and motivations guiding its design. We also describe the platform functionality which includes support for integrating game design elements in learning activities, creating dynamic problems, and visualizing student performance and progress. At the end, we present a usability study of the platform and the assessment results from an end user perspective.

Automated trust negotiation is an approach which establishes trust between strangers through the bilateral, iterative disclosure of digital credentials. Sensitive credentials are protected by access control policies which may also be communicated to the other party. Ideally, sensitive information should not be known by others unless its access control policy has been satisfied. However, due to bilateral information exchange, information may flow to others in a variety of forms, many of which cannot be protected by access control policies alone. In particular, sensitive information may be inferred by observing negotiation participants' behavior even when access control policies are strictly enforced.In this paper, we propose a general framework for the safety of trust negotiation systems. Compared to the existing safety model, our framework focuses on the actual information gain during trust negotiation instead of the exchanged messages. Thus, it directly reflects the essence of safety in sensitive information protection. Based on the proposed framework, we develop policy databases as a mechanism to help prevent unauthorized information inferences during trust negotiation. We show that policy databases achieve the same protection of sensitive information as existing solutions without imposing additional complications to the interaction between negotiation participants or restricting users' autonomy in defining their own policies.

Gamification -the use of game design elements in non-game contexts -has seen rapid adoption in various areas in recent years. Its application in education is particularly promising, due to its potential to shape user behavior in desirable directions through increasing user motivation and engagement. This work-in-progress paper presents a course gamification platform aimed at supporting instructors to gamify courses that target skill development, such as computing-related courses.