If interactive computing systems development is to be considered an engineering discipline, we need methods and tools to help us reason about and predict the quality of systems, from early in the design process. This paper provides a brief overview of work we have been carrying out in the general area of evaluating and ensuring the quality of interactive computing systems. Some of the work currently being carried out is also discussed. Discussed approaches range from the formal verification of user interface models through model checking, to the reverse engineering and model based testing of implemented interactive computing systems.

Spreadsheets are amongst the most successful examples of end user programming. Because of their, still increasing, importance for companies, spreadsheets have drastic economical and societal impact. Hence, locating and fixing spreadsheet faults is important and deserves attention from the research community. A state-of-the-art technique uses genetic programming for generating repair candidates, but a limitation that hinders real-world application is that it still computes too many repair candidates. In this paper, we discuss a novel technique based on constraint solving that uses distinguishing test cases to narrow down the number of repair candidates.

The information infrastructure that pervades urban environments represents a major opportunity for collecting information about Human mobility that would be very important across many application domains. However, this huge potential has been undermined by the overwhelming privacy risks that are associated with such forms of large scale sensing. In this research, we are concerned with the problem of how to enable a set of autonomous sensing nodes, e.g. a Bluetooth scanner or a Wi-Fi hotspot, to collaborate in the observation of movement patterns of individuals without compromising their privacy. We describe a novel technique that generates Precedence Filters and allows probabilistic estimations of sequences of visits to monitored locations and we demonstrate how this technique can combine plausible deniability by an individual with valuable information about aggregate movement patterns. The results provide a promising step towards the application of new stochastic techniques in large scale sensing.

This paper presents a comparative analysis of Free/Libre Open Source Software (FLOSS) Learning Management System (LMS). Following a selection process we analyze the functionalities and characteristics of 8 tools commonly used in formal and informal education. More specifically we focus on the availability of different tools concerning communication and assistance, such as, forum, email, calendar, portfolios, etc. Our analysis showed that despite their similarities, the appropriateness of different FLOSS LMSs can be greatly affected by the specific needs of students, instructors and institutions.

It can be argued that participating in Free/Libre Open Source Software (FLOSS) projects can have a positive effect in the contributor’s learning process. The need to collaborate with other contributors and to contribute to a project can motivate and implicitly foster learning. In order to validate such statements, it is necessary to (1) study the interactions between FLOSS projects’ participants, and (2) explore the didactical value of participating in FLOSS projects, designing an appropriate questionnaire asking FLOSS contributors about their experience in FLOSS projects. In this paper, we illustrate how this questionnaire was designed and disseminated. We conclude the paper with results from 27 FLOSS projects contributors, determining that, not only they contribute and collaborate to the project and its community, but also that FLOSS contributors see that this type of activity can be regarded as a complement to formal education.

It is well known that the classical three- and four-round Feistel constructions are provably secure under chosen-plaintext and chosen-ciphertext attacks, respectively. However, irrespective of the
number of rounds, no Feistel construction can resist related-key attacks where the keys can be offset by a constant. In this paper we show that, under suitable reuse of round keys, security under related-key attacks can be provably attained. Our modification is substantially simpler and more efficient than alternatives obtained using generic transforms, namely the PRG transform of Bellare and Cash (CRYPTO 2010) and its random-oracle analogue outlined by Lucks (FSE 2004). Additionally we formalize Luck’s transform and show that it does not always work if related keys are derived in an oracle-dependent way, and then prove it sound under appropriate restrictions.

The use of powerful mobile devices, like smartphones, tablets and laptops, are changing the way programmers develop software. While in the past the primary goal to optimize software was the run time optimization, nowadays there is a growing awareness of the need to reduce energy consumption. This paper presents a technique and a tool to detect anomalous energy consumption in Android applications, and to relate it directly with the source code of the application. We propose a dynamically calibrated model for energy consumption for the Android ecosystem, and that supports different devices. The model is then used as an API to monitor the application execution: first, we instrument the application source code so that we can relate energy consumption to the application source code; second, we use a statistical approach, based on fault-localization techniques, to localize abnormal energy consumption in the source code .