# Secure Cloud Infrastructure: A Survey on Issues, Current Solutions, and Open Challenges
## 5 Related Existing Solutions in Cloud Levels
### Solutions at Application Level
The results show that the proposed scheme can prevent the man-in-the-middle, replay and forgery attacks. In another recent study [69], the Seamless Secure Anonymous Authentication Scheme (S-SAAS) was proposed to establish a secure session for cloud-based mobile edge computing. This proposed protocol used elliptic-curve cryptography, one-way hash function and less expensive operation to provide seamless connectivity. In addition, this proposed protocol applied a new random integer to withstand potential attacks and satisfies important security features. The authors in [70] recently proposed a novel pairing-free multi-server authentication protocol based on ECC for the MCC environment. The proposed scheme not only offers computational cost-efficiency but also preserves the features of costly pairing schemes, such as the achievement of secure mutual authentication, anonymity and scalability. The strength of the scheme is theoretically illustrated by the formal security model. The authors in [71] developed various models for information and resource sharing among tenants in an IaaS cloud using the Open Stack platform as a reference. The models encourage a tenant to engage its IT resources with other tenants in a controlled method. Nevertheless, the VMs need to be restricted in network access so that malicious software is incapable of transmitting the information in an uncontrolled manner. The work in [72] proposed a novel access control framework for security and privacy issues in the cloud environment. The proposed framework was based on dynamic trustworthiness. Access control that is based on dynamic trustworthiness is applied to decrease the possibility to perform unauthorized activities and to make sure that only authorized users can access cloud resources. The result show that the system identifies malicious behavior to avoid any unauthorized access, will enhance the security of cloud computing, and will therefore lead to an increased trust degree of users. The authors in [73] proposed a hybrid access control framework called iHAC that enables combining the features of type enforcement and role-based access control. The proposed framework enables flexible access control and is unified for IaaS clouds environments. In addition, a VMM-based access control technique was designed to restrict the VM's behaviors to the underlying resources in a fine-grained method. The experimental results show that the iHAC framework helps to make true access control decisions with an acceptable performance overhead. Another study in [74] proposed a dynamic access control approach to solve the multifarious security breaches that occur in the cloud. This approach tends to secure data in the cloud that should address the interrelationship between the requestor, data that are requested, and the action that will be performed on the data. Furthermore, the study considered the user for granting access control dynamically. The result only presented an initial implementation of the proposed approach. A recent study in [75] proposed a blockchain-based access control framework called AuthPrivacyChain and privacy protection in clouds. All authorization that is linked to transactions is posted through the user to the blockchain. Moreover, the framework was designed based on an enterprise operation system (EOS) blockchain to access the permission and the information as a further description of blockchain transactions. Additionally, AuthPrivacyChain provides access control, authorization revocation and authorization. The experimental results show that only legal users can access resources, but AuthPrivacyChain cannot prevent attacks from external users. A study in [76] proposed an approach for cloud identity management with privacy and security improvements based on blockchain. This approach provides a mechanism for authentication and decentralized trust. In the trust model, the cloud service providers (CSPs) do not require pre-configured parameters or rules to establish interactive trust relationships.