Cloud storage is a cheap and reliable solution for users to share data with their contacts. However, the lack of standardisation and migration tools makes it difficult for users to migrate to another Cloud Service Provider (CSP) without losing contacts, thus resulting in a vendor lock-in problem. In this work, we aim at providing a generic framework, named PortableCloud, that is flexible enough to enable users to migrate seamlessly to a different CSP keeping all their data and contacts. To preserve privacy of users, the data in the portable cloud is concealed from the CSP by employing encryption techniques. Moreover, we introduce a migration agent that assists users in automatically finding a suitable CSP that can satisfy their needs.

Although outsourcing data to the cloud has many advantages, cloud computing introduces new privacy and security requirements on how data is stored and accessed. To ensure data confidentiality, use of encryption is a common strategy. A problem with this strategy is that for large data it becomes difficult to access and update data, and to ensure data integrity and data provenance without decrypting all the data. The problem becomes severe when it comes to accessing and modifying large files using mobile devices with limited processing and bandwidth capabilities. In this paper, we present CloudEFS, a novel storage framework to efficiently access and update large encrypted data. A new cached hash algorithm enables efficient updates of data integrity and provenance information. CloudEFS provides improved privacy by hiding not only content but also metadata such as data size, file count, file structure and file history.

Layout managers are used to control the placement of widgets in graphical user interfaces (GUIs). Constraint-based layout managers are among the most powerful. However, they are also more complex and their layouts are prone to problems such as over-constrained specifications and widget overlap. This poses challenges for GUI builder tools, which ideally should address these issues automatically. We present a new GUI builderthe Auckland Layout Editor (ALE)that addresses these challenges by enabling GUI designers to specify constraint-based layouts using simple, mouse-based operations. We give a detailed description of ALE's edit operations, which do not require direct constraint editing. ALE guarantees that all edit operations lead to sound specifications, ensuring solvable and non-overlapping layouts. To achieve that, we present a new algorithm that automatically generates the constraints necessary to keep a layout non-overlapping. Furthermore, we discuss how our innovations can be combined with manual constraint editing in a sound way. Finally, to aid designers in creating layouts with good resize behavior, we propose a novel automatic layout preview. This displays the layout at its minimum and in an enlarged size, which allows visualizing potential resize issues directly. All these features permit GUI developers to focus more on the overall UI design.