3. Detecting and Preventing File Alterations in the Cloud Using a Distributed Collaborative Approach

Cloud Computing is the new trend and this brings new issues and challenges in cyber security since a lot of the data from companies and users is available through the Internet. It is not only about the data but also about the applications that run in the Cloud that could be compromised affecting the service to thousands or millions of users, which may also have their local systems under siege through the exploitation of the security flaws in the Cloud. We propose here an algorithm that can detect unauthorized modifications to any of the files that are kept under custody. It is a collaborative systems where a set of nodes participate to gain also reputation points. This is a light algorithm that requires a time complexity of only O(n) times hashings in total. In our algorithm is implemented a technique to avoid the Hash Value Manipulation Attack that is one kind of Man-in-the-middle attack used to replace hash values. Any unauthorized modification of a file is detected and reported without the need of a third party auditor, which is another advantage.