Abstract. This paper deals with test data set selection from algebraic specifications. Test data set are generated from selection criteria which are usually defined to cover specification axioms. The unfolding selection criterion consists in covering the input domain of an operation using case analysis. The unfolding procedure can be iterated in order to split input domains of operations into finer subdomains. In this paper we propose to extend an unfolding procedure previously developed in [6, 22]. This yields a generic extension which can be applied to any positive conditional specification with constructors.

Distributed denial of service attacks represents one of the most important threats to cloud-providers. Over the years, volumetric DDoS attacks have become increasingly important and complex. Due to the rapid adaptation of attackers to the detection and mitigation methods designed to counter them, the industry needs to constantly monitor and analyse the attacks they face. In this paper, we present an overview of the attacks that were perpetrated against our infrastructure in 2021. Our motivation is to give an insight of the challenge that DDoS attacks still represent within a large European cloud provider