Slim Kallel

In today’s competitive business environments, organizations increasingly need to model and deploy flexible and cost effective business processes. In this context, configurable process models are used to offer flexibility by representing process variants in a generic manner. Hence, the behavior of similar variants is grouped in a single model holding configurable elements. Such elements are then customized and configured depending on specific needs. However, the decision to configure an element may be incorrect leading to critical behavioral errors. Recently, process configuration has been extended to include Cloud resources allocation, to meet the need of business scalability by allowing access to on-demand IT resources. In this work, we propose a formal model based on propositional satisfiability formula allowing to find correct elements configuration including resources allocation ones. In addition, we propose to select optimal con- figurations based on Cloud resources cost. This approach allows to provide the designers with correct and cost-effective configuration decisions.

The COVID‐19 pandemic has emerged as a highly transmissible disease which has caused a disastrous impact worldwide by adversely affecting the global economy, health, and human lives. This sudden explosion and uncontrolled worldwide spread of COVID‐19 has revealed the limitations of existing healthcare systems regarding handling public health emergencies. As governments seek to effectively re‐establish their economies, open workplaces, ensure safe travels and progressively return to normal life, there is an urgent need for technologies that may alleviate the severity of the losses. This article explores a promising solution for secure Digital Health Certificate, called NovidChain, a Blockchain‐based privacy‐preserving platform for COVID‐19 test/vaccine certificates issuing and verifying. More precisely, NovidChain incorporates several emergent concepts: (i) Blockchain technology to ensure data integrity and immutability, (ii) self‐sovereign identity to allow users to have complete control over their data, (iii) encryption of Personally Identifiable Information to enhance privacy, (iv) W3C verifiable credentials standard to facilitate instant verification of COVID‐19 proof, and (v) selective disclosure concept to permit user to share selected pieces of information with trusted parties. Therefore, NovidChain is designed to meet a high level of protection of personal data, in compliant with the GDPR and KYC requirements, and guarantees the user's self‐sovereignty, while ensuring both the safety of populations and the user's right to privacy. To prove the security and efficiency of the proposed NovidChain platform, this article also provides a detailed technical description, a proof‐of‐concept implementation, different experiments, and a comparative evaluation. The evaluation shows that NovidChain provides better financial cost and scalability results compared to other solutions. More precisely, we note a high difference in time between operations (i.e., between 46% and 56%). Furthermore, the evaluation confirms that NovidChain ensures security properties, particularly data integrity, forge, binding, uniqueness, peer‐indistinguishability, and revocation.