# Secure Cloud Infrastructure: A Survey on Issues, Current Solutions, and Open Challenges
## 5 Related Existing Solutions in Cloud Levels
### Solutions at Application Level
Therefore, this approach manages trust relationships between the clients and CSPs effectively and ensures secure IaaS for cloud federations. The results show the effectiveness of the proposed identity management blockchain-based approach while improving privacy and security capabilities. The authors in [77] proposed a novel dynamic trust model for federated identity management (FIM) based on fuzzy cognitive maps. This model aimed at evaluating trustworthiness relationships between unknown entities dynamically and securely which makes FIM more flexible and scalable to be maintained and deployed in the cloud. Furthermore, the proposed model provides a set of trust features that serve as a basis for quantifying and modeling the trust level of unknown entities. The study in [78] introduced a framework that enables the CSPs to supply the identity and access management (IAM) as a public cloud service, which is also called IAMaaS. This framework aims at ensuring that the collection of identities complies with the cloud. According to the authors, the IAMaaS can work perfectly with an existing on-premise platform in a hybrid manner to promote the capacity of security. In addition, the IAMaaS enables users to define the virtual private area in cloud space to enhance the security and protection of their resources. The researchers in [79] proposed an identity management system (IDMS) to preserve the security of communication among servers and clients in cloud computing. The proposed system relied on the dual certificate manager (DCM) technique for authorizing and authenticating users to avoid privacy violations. The DCM technique uses token-based terminology for tracking and easy data access, which lead to downsizing the domain of the attacks. Additionally, this technique was commonly applied for the SSL/TLS protocol to protect data transmission. To conclude, the review of solutions in the literature at the application level revealed that solutions at this level focused on the use of IDS/IPS techniques to mitigate the risks associated with DDoS and EDoS. These techniques have certain limitations, such as ineffectiveness when dealing with complex and unknown patterns of attacks, while the cloud needs techniques that can detect and/or prevent sophisticated attacks. In addition, the existing access control and identity management solutions (e.g., traditional firewall, encryption, and virtualized access control) at this level are not appropriate to promote security, because these solutions have a deficiency in managing the privileges the trust relationships needed to prevent the internal/external attackers. Consequently, the researchers should incorporate advanced techniques such as blockchain. Moreover, numerous models used various techniques for authentication, but there are many barriers against implementing these techniques, such as the different testing environments and the use of a small amount of data during the verification process. This does not give confidence in the suitability of the models in the cloud computing environment even. Additionally, biometric systems are emerging as one of the best solutions to improve authentication security and privacy. Biometric systems play a key role in government and commercial applications outsourced to the cloud. Therefore, security and privacy are the biggest concerns for users. Unfortunately, most of these techniques are complex, impractical, and time-consuming.