My Private Google Calendar

Everybody loves Google Apps. Google provides highly available web applications that help you communicate, organize and collaborate from anywhere using different interfaces in the most user friendly and efficient way, without being worried about any IT issues. However, some people still hesitate using Google services because of privacy and trust issues. In this paper, we identify privacy issues in GoogleWeb Applications as a particularly vital problem and propose a solution. In our solution a transparent encryption layer is put between the user and the cloud service provider on a site trusted by the user. This layer accesses the request and response messages passed between the two parties in a fine-grained manner. It applies modern cryptography techniques to encrypt the data without sacrificing functionality and portability of the cloud service. This way the trust of the end user can be reobtained and he or she will be encouraged to further enjoy using web applications such as Google Apps without having to worry about privacy issues

Changing flights in mid-air: a model for safely modifying continuous queries

Continuous queries can run for unpredictably long periods of time. During their lifetime, these queries may need to be adapted either due to changes in application semantics (e.g., the implementation of a new alert detection policy), or due to changes in the system’s behavior (e.g., adapting performance to a changing load). While in previous works query modification has been implicitly utilized to serve specific purposes (e.g., load management), to date no research has been done that defines a general-purpose, reliable, and efficiently implementable model for modifying continuous queries at run-time. In this report, we introduce a punctuation-based framework that can formally express arbitrary lifecycle operations on the basis of input-output mappings and basic control elements such as start or stop of queries. On top of this foundation, we derive all possible query change methods, each providing different levels of correctness guarantees and performance. We further show how these models can be efficiently realized in a state-of-the-art stream processing engine; we also provide experimental results demonstrating the key performance tradeoffs of the change methods

Changing flights in mid-air: A model for safely modifying continous queries

Continuous queries can run for unpredictably long periods of time. During their lifetime, these queries may need to be adapted either due to changes in application semantics (e.g., the implementation of a new alert detection policy), or due to changes in the system’s behavior (e.g., adapting performance to a changing load). While in previous works query modification has been implicitly utilized to serve specific purposes (e.g., load management), to date no research has been done that defines a general-purpose, reliable, and efficiently implementable model for modifying continuous queries at run-time. In this report, we introduce a punctuation-based framework that can formally express arbitrary lifecycle operations on the basis of input-output mappings and basic control elements such as start or stop of queries. On top of this foundation, we derive all possible query change methods, each providing different levels of correctness guarantees and performance. We further show how these models can be efficiently realized in a state-of-the-art stream processing engine; we also provide experimental results demonstrating the key performance tradeoffs of the change methods

POP: A new encryption scheme for Dynamic Databases

This technical report explores a new technique called POP. POP addresses the need to encrypt databases in the cloud and to execute complex SQL queries on the encrypted data efficiently. POP can be configured to meet different attacker scenarios. We present security results for four such adversary models. Furthermore, we present the results of performance experiments conducted using the TPC-H benchmark and an off-the-shelf relational database system in order to study the performance overheads of POP