This paper formalises the security of programmable secure computation focusing on simplifying security proofs of new algorithms for existing computation frameworks. Security of the frameworks is usually well established but the security proofs of the algorithms are often more intuitive than rigorous. This work specifies a transformation from the usual hybrid execution model to an abstract model that is closer to the intuition. We establish various preconditions that are satisfied by natural secure computation frameworks and protocols, thus showing that mostly the intuitive proofs suffice. More elaborate protocols might still need additional proof details.

Privacy regulations, such as GDPR, impose strict requirements to organizations that store and process private data. Privacyenhancing technologies (PETs), such as secure multi-party computation and differential privacy, provide mechanisms to perform computations over private data and to protect the disclosure of private data and derivatives thereof. When PETs are used to protect individual computations or disclosures, their privacy properties and their effect on the utility of the disclosed data can be straightforwardly asserted. However, when multiple PETs are used as part of a complex and possibly interorganizational business process, it becomes non-trivial for analysts to fully grasp the guarantees that the combined set of PETs provide overall. This article presents a multi-level approach to analyze privacy properties of business processes that rely on PETs to protect private data. The approach is embodied in an open-source toolset, Pleak, that allows analysts to capture privacy-enhanced business process models and to characterize and quantify to what extent the outputs of a process leak information about its inputs. Pleak incorporates an extensible set of analysis plugins, which enable users to inspect potential leakages at multiple levels of detail.