Industrial Internet of Things (IIoT) plays a central role in the Fourth Industrial Revolution, with many specialists working towards implementing large scalable, reliable and secure industrial environments. However, existing environments are lacking security standards and have limited resources per component which results in various security breaches, e.g., trust in between the components, partner factories or remote control units with the system. Due to the resilience and its security properties, combining blockchain-based solutions with IIoT environments is gaining popularity. Despite that, chain-structured classic blockchain solutions are extremely resource-intensive and are not suitable for power-constrained IoT devices. To mitigate the referred security challenges, a secure architecture is proposed by using a DAG-structured asynchronous blockchain that can provide system security and transactions efficiency at the same time. Use-cases and sequence diagrams were created to model the solution. The achieved results are robust, supported by an extensive security evaluation, which foster future developments over the proposed architecture. Therefore, as the proposed architecture is generic and flexible, its deployment in diverse customized industrial environments and scenarios, as well as the incorporation of future hardware and software, is possible.
