[Borkar*, 4.(12): December, 2015] ISSN: 2277-9655 (I2OR), Publication Impact Factor: 3.785 http: // www.ijesrt.com © International Journal of Engineering Sciences & Research Technology [101] IJESRT INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY A SECURITY OF CLOUD DATA IN FULLY HOMOMORPHIC ENCRYPTION Aachal R. Borkar*, Prof. Vijay Bagdi * WCC DEPT. A.G.P.C.O.E, NAGPUR . WCC DEPT. A.G.P.C.O.E,NAGPUR. ABSTRACT The advancement in technology, industry, e-commerce and research. A large amount of complex and pervasive digital data is being generated which is increasing at an exponential rate and often termed as Big data. For analyse and handling such big data various tools are available.The cloud computing is resolved for the problems arrises in big data storage.Data security is major issues in the cloud can be enhance by fully homomorphic encryption technique. As the cloud, data storage can be manage by clustering for security and privacy of data. In this paper, a brief introduction of fully homomorphic encryption technique and digital signature can be also applicable as security in future aspect. KEYWORDS: Data security, Unauthorized person, Cloud Computing, Security, k-means clustering (4 hosts), Digital Signature. INTRODUCTION Cloud computing refers to the web-based computing, providing users or devices with shared pool of resources, information or software on demand and pay per-use basis. It frees a user from the concerns about the expertise in the technological infrastructure of the service. It allows end user and small companies to make use of various computational resources like storage, software and processing capabilities provided by other companies. Internet has been a driving force towards the various technologies that have been developed since its inception. Arguably, one of the most discussed among all of them is Cloud Computing. Over the last few years, cloud computing paradigm has witnessed an enormous shift towards its adoption and it has become a trend in the information technology space as it promises significant cost reductions and new business potential to its users and providers. The advantages of using cloud computing include: i) reduced hardware and maintenance cost, ii) accessibility around the globe, and iii) flexibility and highly automated processes wherein the customer need not worry about mundane concerns like software up-gradation. WHAT IS CLOUD COMPUTING? Cloud computing is defined as a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources (e.g. networks, servers, storage devices and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction. they can be accessed from any computer in any part of the world. This integrates features supporting high scalability and multi-tenancy, offering enhanced flexibility in comparison to the earlier existing computing methodologies. It can deploy, allocate or reallocate resources dynamically with an ability to continuously monitor their performance.figure1 shows the cloud general model in which the basic purpose model of cloud are used in the structure for the data storage and how the users are accessing the data from the cloud there are number of users of cloud based on the requirement we can established the model for the users as per the requirement of users.