• Cloud Security is a sub-domain of computer security, network security, and Information security. Security in the cloud is a major concern.
• Data in the cloud be stored in encrypted form. To restrict the client from direct accessing the shared data, proxy and brokerage services should be employed.
• It includes broad set of policies, technologies, and controls deployed to protect data, applications, and the associated infrastructure of cloud computing.

Security Planning

• Before deploying a particular resource to cloud, one should need to analyze several attributes about the resource such as:
• Select which resources he is going to move to cloud and analyze its sensitivity to risk.
• Consider cloud service models such as IaaS, PaaS, and SaaS. These models require consumer to be responsible for security at different levels of service.
• Consider which cloud type such as public, private, community or hybrid.
• Understand the cloud service provider's system that how data is transferred, where it is stored and how to move data into and out of cloud.

Security of Cloud

Security Boundaries: A particular service model defines the boundary between the responsibilities of the service provider and consumer. Cloud Security Alliance (CSA) stack model defines the boundaries between each service model and shows how different functional units relate to each other

• IaaS is the most basic level of service with PaaS and SaaS next two above levels of service.
• Moving upwards each of the services inherits capabilities and security concerns of the model beneath.
• IaaS provides the infrastructure, PaaS provides platform development environment and SaaS provides the operating environment.
• IaaS has the least level of integrated functionalities and integrated security while SaaS has the most.
• This model describes the security boundaries at which cloud service provider's responsibility ends and the consumer's responsibilities begin.
• Any security mechanism below the security boundary must be built into the system and above should be maintained by the consumer.

Note: Although each service model has security mechanism security needs also depends upon where these services are located, in private, public, hybrid or community cloud.

Data Security:

Since all the data is transferred using the Internet, data security is of major concern in the cloud. Here are key mechanisms for protecting data mechanisms listed below:

• Access Control
• Auditing
• Authentication
• Authorization

All of the service models should incorporate security mechanism operating in all above-mentioned areas.

Since data stored in the cloud can be accessed from anywhere, therefore to protect the data, we must have a mechanism to isolate data from direct client access.

Brokered Cloud Storage

Brokered Cloud Storage Access is one of the approaches for isolating storage in the cloud. In this approach, two servers are created:

1.       A broker with full access to storage but no access to the client.

2.      A proxy with no access to storage but access to both client and broker.

Working on Brokered cloud storage access system.

• When the client issue request to access data:
• The client data request goes to proxy's external service interface.
• The proxy forwards the request to the broker.
• The broker requests the data from cloud storage system.
• The cloud storage system returns the data to the broker.
• The broker returns the data to the proxy.
• Finally, the proxy sends the data to the client.

Encryption: Encryption helps to protect data from being compromised. It protects data that is being transferred as well as data stored in the cloud. Although encryption helps to protect data from any unauthorized access, it does not prevent from data loss.