# A Cross-Chain-Based Access Control Framework for Cloud Environment
## 8 Conclusions  
The integration of blockchain technology into the cloud has proven to be one of the most promising solutions to address security issues raised within distributed cloud environments. Smart contracts reduce the risk of human errors, and the BC's inherent cryptographic technique and specific consensus mechanism prevent hacker attacks effectively.  
The heterogeneity of blockchain and the lack of an inter-chain communication standard lead to a slow pace of adoption. Several interoperability propositions based on inter-chain communication technology, such as Cosmos, Hyperledger, and Polkadot, have emerged, leading to the development of the IBC protocol, which unifies the blockchain network.  
In this work, we elaborated a framework based on cross-chain technology, allowing two cloud zones, back-end and front-end, to communicate by integrating the IBC core modules while offering a semantically enriched attribute-based access control mechanism.  
Most of the highlighted works still trust certification authorities, as shown by our studies on current blockchain-based access control solutions in the cloud. In contrast, our framework is built on cross-chain technology to relay cloud consumers and the sought resources. We also deployed semantic and modular AC, granting more flexibility to the framework.  
In our framework, the cloud users are connected to the network as BC nodes that integrate IBC modules, authenticated by BC built-in accounts, and authorized to access the cloud assets through a semantic, fine-grained access control.  
In the future, we will conduct tests on public blockchain networks with a thorough analysis of associated costs, investigate the potential threats this framework could face, highlight the different types of attacks that cloud could face (web 2.0 vs. web 3.0), evaluate the performance of our framework on other cloud service providers than GCP, and discuss the possibility of combining the proposed framework with other security mechanisms to strengthen the confidentiality, integrity, and availability of cloud resources while addressing traceability issues related to cloud stakeholders' activities. We are also currently working to introduce a decentralized self-sovereign identity roll-up in order to avoid the heavy reliance on the CSC (sending chain) as a certification authority for centric-identity verification. Finally, we will investigate how to make the cross-chain bridge to other non-IBC blockchains like Ethereum or Avalanche.  
Conceptualization, S.B., M.Z., S.A., A.T. and A.B.; methodology, S.B., M.Z., S.A., A.T. and A.B.; writing--original draft preparation, S.B.; writing--review and editing, S.B., M.Z., S.A., A.T. and A.B.; visualization, S.B.; supervision, M.Z., S.A., A.T. and A.B.; project administration, M.Z. and A.B. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Dataset available on request from the authors.  
This study was performed within the framework of the 5G-Medic project supported by Federal Public Service (FOD) Belgium, Cybersecurity Research Program Flanders-second cycle (VOEWICS02), and EU COST Action CA22104 (Behavioral Next Generation in Wireless Networks for Cyber Security).  
The authors declare no conflicts of interest.