# RACHEM: Reinforced Reliable Computing in Cloud by Ensuring Restricted Access Control
## 2 Literature Survey
### Algorithmic Procedure for RACHEIM
### Performance Overhead and Scalability Analysis

Performance impact and scalability concerns associated with RACHEIM are discussed below:

* The proposed work has been simulated using the Salesforce cloud platform that supports dynamic user role configurations, hierarchical access models, and scalable resource provisioning. This enabled the validation of the system's performance in the context of evolving access demands and enterprise role hierarchies. * The proposed approach incorporates partial homomorphic encryption specifically for securing sensitive access control elements such as role secret values and user decryption keys, rather than encrypting bulk data. This selective encryption strategy significantly reduces computational costs and ensures that performance bottlenecks are avoided during frequent access validations. * Furthermore, to enhance scalability, the RACHEIM model leverages Salesforce's metadata-driven policy management, which allows for dynamic updates of access control policies and inheritance hierarchies without requiring re-encryption of existing data. The work also implements a checkpoint-based validation mechanisms which limits redundant cryptographic operations and further minimizes latency, particularly as the role hierarchy expands. Hence, the proposed model ensures an access control scheme that not only strengthens security but also maintains operational efficiency across hierarchical role structures, making it suitable for scalable and real-world cloud environments. ## 5 Formal Analysis of RACHEIM

To validate the simulation of the proposed approach, this section demonstrates a formal security analysis of the RACHEIM scheme using Canetti and Krawczyk's Adversary

Figure 8: Simulation of RACHEIM in salesforce depicting system admin profile. Figure 9: Simulation of RACHEIM role hierarchy in salesforce. Model (C and K) [95]. This work manifests formal theorems to preserve confidentiality, maintain role secrecy, and revoke unauthorized access. **Theorem 1** (Confidential Secret Key Preservation under Encrypted Computation). : _Let P be the key exchange protocol implemented in the RACHEIM model, operating under the assumptions of the Canetti-Krauczyk (C and K) security framework. In the presence of an unauthenticated communication model (UM), where adversaries can observe, intercept, and inject messages, the RACHEIM protocol ensures that the confidentiality and integrity of the secret key is preserved, provided that the underlying encryption and key derivation functions are semantically secure and resistant to replay and impersonation attacks._

Proof Sketch:For preserving the generated Secret Key in the RACHEIM approach, the formal analysis considers the Party Corruption attack, wherein a vulnerable CSP (considered as a Party) could leak the credentials of the computed public and private keys to the attacker. The RACHEIM approach utilizes homomorphic encryption while encrypting the data and then uploads the encrypted data on the CSP. Hence, even if the integrity of the CSP is compromised, the secrecy of the key is maintained. Furthermore, if the adversary manages to steal the key credentials in the unauthenticated link model (UM), due to a vulnerable CSP, the privacy of the owner's data is still maintained since the CSP does not have direct access to the original data. The homomorphic nature allows computation without decryption, and the key is never exposed to the CSP. Hence, confidentiality is preserved. Initial information:

**SIG SECRET KEY**

Step1: The initiator [Data Owner (DO)] initiates the Key Generation request (DO, u, v, time t) // u and v are random large prime numbers, and t is the time instance at which a request is initiated. Step2: Compute n = (u*v), for each new time instance t.

Step3: Compute (Division-based_PHE using (n, e))

Step4: Send \(\rightarrow\) Compute (encrypted text, division-operator) to CSP

Upon receiving the encrypted data and the division operator, the CSP performs the computation on the encrypted text.