# RACHEM: Reinforced Reliable Computing in Cloud by Ensuring Restricted Access Control
## 2 Literature Survey
### Algorithmic Procedure for RACHEIM
## 6 Conclusions

The cloud ecosystem, by its multi-tenant nature, is inherently vulnerable to unauthorized access and network-based attacks. To address these security challenges, this study proposes a reinforced framework--RACHEIM--designed to mitigate risks associated with vulnerable CSPs and to enhance identity and access management (IAM) policies through a two-phase mechanism. In the first phase, the proposed model integrates role-based access control (RBAC) with a homomorphic encryption scheme via a secure cipher cloud gateway. The model encapsulates the original data into an encrypted form using a division-based operator, thereby preserving data integrity and safeguarding against malicious intrusions. Simulation results demonstrate that RACHEIM significantly reduces encryption and decryption execution times compared to conventional homomorphic encryption approaches, such as Multiplicative RSA and Additive Paillier schemes. In the second phase, RACHEIM enforces identity management and privileged access through a dynamic role hierarchy,effectively securing cloud computing systems from unauthorized and malicious users. Simulation findings show that the proposed model achieves approximately 40% reduction in encryption time and 20% reduction in decryption time compared to the Paillier additive homomorphic encryption method. Furthermore, RACHEIM outperforms the RSA multiplicative approach with an approximate 20% improvement in encryption efficiency and a 15% improvement in decryption performance. The simulation was conducted in alignment with current industry standards, using a 2048-bit key size and data size. Additionally, the role hierarchy mechanism was validated in a real-world Salesforce cloud environment, confirming the practical feasibility of the proposed approach. The model's key permission validation and dynamic policy update capabilities were further substantiated through formal analysis based on [PERSON] and [PERSON]'s adversarial communication model, ensuring rigorous verification of access control logic under threat conditions. ## 7 Future Work and Limitations

The proposed work presents a robust framework for secure access control using role-based mechanisms and partial homomorphic encryption. However, there is considerable scope for further enhancement and application. In our future work, we aim to integrate machine learning-based anomaly detection systems within the access control layer to dynamically monitor access patterns and proactively identify malicious service nodes that may indicate potential insider threats. These adaptive techniques can complement the static ACLs and RBAC models, thereby strengthening security in multi-tenant cloud infrastructures. Additionally, we intend to expand the proposed model to support cross-cloud federated identity and access management (IAM), particularly in hybrid and multi-cloud deployments. This would involve implementing interoperability mechanisms to handle authentication and policy enforcement across various cloud providers while maintaining user privacy and data security. The proposed model can also be adapted to support immersive technologies like AR, VR, and the Metaverse. These technologies rely heavily on cloud-based data sharing and multi-user environments. RACHEIM can support these emerging technologies through the following actions:

* Providing secure access enforcement to spatial data and user-generated assets stored in the cloud through role-tokenized credentials;
* Allowing dynamic role mapping and key distribution for participants in collaborative environments (e.g., multiple VR users with differing access levels);
* Preserving data confidentiality during real-time computations (e.g., rendering 3D models or avatar interactions) via partial homomorphic encryption without revealing plaintext data to the cloud or third parties. Future studies may also consider the overhead introduced by encryption at scale and explore lightweight cryptographic primitives or post-quantum secure algorithms to maintain performance without compromising security.