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.

Business-to-business (B2B) e-commerce market is expected to expand rapidly in coming years. In this context, organizations tend to rely more on business process management (BPM) to streamline their operations. The business process field is influenced by a wide range of temporal constraints which rise from legal, regulatory, and managerial rules. One of the most promising standards for business process modeling, namely the Business process Model and notation BPMN poorly addresses the time dimension so far. In this paper, we elaborate an extension to BPMN 2.0 to handle the time dimension. The aim of this BPMN extensions is to support business analysts and modellers in easily including the needed temporal constraints in their processes. We motivate and justify our proposed extensions by means of illustrative case studies. Furthermore, based on the proposed extensions, a verification approach based on the model checking technique is used to diagnose potential temporal violations of the process model. The work presented in this paper sets foundation for later automation of these constraints through process execution engines.

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Formal specification and verification support of time-related constraints constitute fundamental challenges for any Business Process Management (BPM) system. Reluctantly, the literature on the subject of formal specification and verification of advanced temporal constraints such as absolute temporal constraints associated with relative temporal constraints is scarce. In this paper, we propose a novel approach enabling the formal specification and verification of advanced temporal constraints of business processes. The particularity of our approach is that it caters for relative and absolute related temporal constraints while relying on the dependencies that can exist between theses constraints. In fact, it is important to deal with such dependencies to handle the violations that can arise as soon as possible at design step. To do so, we propose a formal approach which relies on the timed automata formalism. In this context, we propose a set of mapping rules and algorithms where the semantic of timed automata is preserved even if we deal with absolute and relative temporal constraints. Using the defined formal model, we investigate a model checking based verification process that aims at validating business processes against their absolute and relative temporal constraints.