Privacy-Preserving Processing

Privacy preserving processing deals with the design of mechanisms that enable the cloud to process encrypted data. Ideally, cloud providers should be able to conduct any complex operations on the outsourced data. While advances in fully homomorphic encryption are promising, they are still too computationally intensive to represent a viable solution for privacy preserving processing. This is why, in TREDISEC, we focus on a different line of research that aims at designing dedicated privacy preserving mechanisms for specific applications. More specifically, we address the problem of privacy preserving data processing for biometric data and privacy preserving word search:One of the most demanding operation for cloud application is word search. A data owner or another authorized third party should be able to search for some words over the data that has already been outsourced encrypted. The idea is to exploit the properties of the outsourced data and the functions we are interested in to come up with efficient security solutions that do not negatively impact the performances of cloud computing.

Authenticated Encryption

Authenticated encryption with new security model and construction. StoA authenticated encryption with variable stretch is vulnerable to some attacks that misuse the variable stretch. A new security definition is proposed and followed by a new construction.


A multi-user searchable encryption solution that allows users (called writers) to outsource their encrypted documents. Afterwards, other users (called readers) can perform some word search operations without the need of re-downloading the entire document and only if they are authorized to do so.