Srdjan Marinovic

Marco Guarnieri, Srdjan Marinovic, David Basin

Databases can leak confidential information when users combine query results with probabilistic data dependencies and prior knowledge. Current research offers mechanisms that either handle a limited class of dependencies or lack tractable enforcement algorithms. We propose a foundation for Database Inference Control based on ProbLog, a probabilistic logic programming language. We leverage this foundation to develop Angerona, a provably secure enforcement mechanism that prevents information leakage in the presence of probabilistic dependencies. We then provide a tractable inference algorithm for a practically relevant fragment of ProbLog. We empirically evaluate Angerona's performance showing that it scales to relevant security-critical problems.

Claudio Soriente, Ghassan Karame, Hubert Ritzdorf et al.

Although cloud storage platforms promise a convenient way for users to share files and engage in collaborations, they require all files to have a single owner who unilaterally makes access control decisions. Existing clouds are, thus, agnostic to shared ownership. This can be a significant limitation in many collaborations because one owner can, for example, delete files and revoke access without consulting the other collaborators. In this paper, we first formally define a notion of shared ownership within a file access control model. We then propose a solution, called Commune, to the problem of distributively enforcing shared ownership in agnostic clouds, so that access grants require the support of a pre-arranged threshold of owners. Commune can be used in existing clouds without requiring any modifications to the platforms. We analyze the security of our solution and evaluate its scalability and performance by means of an implementation integrated with Amazon S3.