ULB | QualSec
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I.  Description of QualSec

The researches undertaken in the QualSec cryptography and computer security group are dedicated to the design and analysis of cryptographic protocols and to the cryptanalysis (side channel attacks) of cryptographic devices. In addition to their researches, the members of the QualSec cryptography and computer security group are involved in consulting and training missions for the industry.

Part of the Computer Science Department of the Science Faculty of the Universite Libre de Bruxelles, the ULB QualSec Research Lab gathers 2 full–‐time, 3 post–‐docs and 6 PhD students with backgrounds from computer science, telecommunications and mathematics. The research group has developed an a thorough knowledge and expertise in the design and analysis of cryptographic protocols (fair exchange, non–‐repudiation protocols, evoting, certified emails, …), in physical attacks based on hardware systems based on machine learning techniques and in countermeasures against side channel attacks. Its academic activity produced more than 50 international publications over the last 5 years. The list of publications of the ULB QualSec Research Lab is available here.

II. Key persons in the project

III. Contributions to the project

Cloud storage’ has became very popular phrase, in the electronic domain, since the last decade. The facility of cloud storage contributes in the storage space of the machine (eg. computer). This idea enables the user to outsource an external platform (storage device like CPU) to store its data. The user who needs these data can download them from the cloud. Now straight forward execution of these correspondences may effect the security of the communication, specially for the classified data, as in general the user who uploads the data over the cloud do not want the owner of the cloud to be able to learn the contents of the data, and also many times it may be desired that the data could be downloaded only by the authorised users.

To achieve such features in the communication with cloud storage, certain tools are required to be wisely devised in such a setup. This work package of the SeCloud project attempts to design and analyse various public-key cryptographic primitives dedicated for the efficiency and security of such communications in the presence of the cloud storage. Various primitives in public key cryptography (PKC) are designed with considering the presence of a trusted third party (TTP) (for example the private key generator in the identity-based setting) for security perspectives. In a wider view, this work package attempts to explore the possibility of design and analysis of efficient cryptographic primitives in the framework of cloud computing, travelling from full dependency on the TTP to the lease possible dependency on the TTP.

More technically, the objective of this work package includes design of public key cryptographic protocols for users authentication, data privacy, integrity and confidentiality with the implication of different kinds of fully TTP and semi TTP. The work also includes full analysis of the designed schemes by the means of a thorough security proof and counts of computational overheads to observe their practical applicability for implementations.

To take into account the above objectives of security viz. authentication, integrity, confidentiality etc., we have designed concrete schemes of encryption and digital signature. In some of these designs we have also attempted to achieve additional features for example searching over the encryption. In the design of digital signatures, we have achieved different properties of various digital signatures by combining them carefully. Most importantly and appealing, we have tried to achieve these constructions on some relevant platforms of public key cryptography e.g. identity-based setting, which supports practical implementations for real world applications. Another important relevance of the work package is that, in the view of recent quantum threats for the existing cryptographic (security) algorithms, we have also realised quantum-immune constructions (i.e. post-quantum cryptosystems) which is a new hope of future cryptography for advanced security concerns.

Last but not the least, when the algorithms, for the real world implementations, are subjected to check against the threats or attacks, analysis of the algorithms against the side-channel attacks are important. To make this work package complete some analytical summary of possible side-channel attacks on the PKC are also observed and discussed.

Institute: Université Libre de Bruxelles

Research unit: QualSec

Projects: BruFence, Scaut, Secloud