Abstract
With progress of the Internet, cloud computing attracts attention as important infrastructure also in the company. Here, there are public Cloud, private Cloud, and also hybrid Cloud that combined these in the usage pattern of cloud computing. Generally, the company is wavering from a viewpoint of various risk sides to use of public cloud computing. In this study, in order to contribute to the cost reduction of a company, or Green IT-ization, the risk management of public cloud computing is established, and public Cloud use of a company is promoted. Specifically, the risk at the time of using public cloud computing based on the result of precedence study is shown quantitatively. Specifically, the assurance which is the main countermeasures is applied. Thus, present public Cloud's risk degree is calculated first. Next, public Cloud's risk degree by assurance application is calculated. Public Cloud's risk degree by assurance application became a value close to hybrid Cloud, and these results were able to confirm the effectiveness. By calculating the cost which assurance takes, a future problem clarifies cost effectiveness and contributes to public Cloud's spreading and promotion.
