Data Storage Security in Cloud Using a Functional Encryption Algorithm P. Vijaya Bharati and T. Sita Mahalakshmi Abstract Cloud computing is a centralized or a distributed computing system built on physical or virtualized resources over large data centers. Security in the cloud has become one of the major significant concerns. This paper considers current paradigms used and implements a functional encryption scheme by using a fully homomorphic algorithm. A trusted third party is used in which a software component called a trusted system is installed. This system uses a security-level adapter that assigns a security level to various types of data stored by the user. It receives the encrypted data from the cloud user with the security level. Depending upon that level the admission controller divides the data into a number of shares equal to the level number. The security controller sends each share to each instance of the image using functional encryption. In this paper the functional encryption uses homomorphic encryption. The cloud server stores the encrypted data in again encrypted format. Homomorphic encryption easily allows us to perform mathematical computations on encrypted data. Keywords Cloud computing Á Security level adapter Á Admission controller Á Security controller Á Trusted third party Á Trusted system Á Functional encryption Á Homomorphic encryption 1 Introduction Cloud computing has been evolved from various technologies all combined to change the organizational traditional thinking of building the IT infrastructure by investing a large amount of money. The cloud is where we choose technology when P. Vijaya Bharati Department of CSE, Vignan’s Institute of Engineering for Women, Visakhapatnam, India e-mail: pvijayabharati@gmail.com T. Sita Mahalakshmi (&) Department of CSE, GITAM University, Visakhapatnam, India e-mail: sanevani.55@gmail.com © Springer Science+Business Media Singapore 2016 N.R. Shetty et al. (eds.), Emerging Research in Computing, Information, Communication and Applications, DOI 10.1007/978-981-10-0287-8_18 201