Cloud computing has become new trend, which many enterprises wants to incorporates in their working. Since it relies on sharing of computing resources rather than having local servers or personal devices to handle applications. Cloud computing offers reduced capital expenditure, operational risks, complexity and maintenance, and increased scalability while providing services at different abstraction levels, namely Software-as-a-Service (SaaS), Platform-as-a-Service (PaaS), and Infrastructure-as-a-Service (IaaS)[3] It is used in consumer-oriented applications such as financial portfolios delivering personalized information, or power immersive computer games. The cloud computing however, has not gained wide acceptance. For which the main reason is security issue. Cloud computing is surrounded by many security issues like securing data, data integrity and examining the utilization of data in cloud by the cloud computing vendors This paper is study of various security threats posed to the data stored in cloud and also threats concerned to both user and vendors in cloud computing. This is a literature survey of various key security threats associated with cloud computing. It also includes a critical analysis of various research papers on same grounds. At the same time it discusses various security models and tools proposed in those papers in order to protect data confidentiality and provide security to the data in cloud computing.

1. Uma Somani , Kanika Lakhani and Manish Mundra presented "Implementing Digital Signature with RSA Encryption Algorithm to Enhance the Data Security of Cloud in Cloud Computing" at IEEE 2010 1st International Conference on Parallel, Distributed and Grid Computing (PDGC - 2010)
2. G. Jai Arul Jose, C. Sajeev, Dr. C. Suyambulingom presented " Implementation of Data Security in Cloud Computing" at International Journal of P2P Network Trends and Technology- Volume1Issue1- 2011
3. Volker Fusenig and Ayush Sharma Security ,"Architecture for Cloud Networking" presented at IEEE 2012 International Conference on Computing, Networking and Communications, Cloud Computing and Networking Symposium .
4. Zhang Xin Lai Song-qing and Liu Nai-wen presented Research on Cloud Computing Data Security Model Based on Multi-dimension 2012 IEEE Internatinal symposium on information technology in medical and education .
5. M. Sudha, Dr. Bandaru Rama Krishna Rao and M. Monica published "A Comprehensive Approach to Ensure Secure Data Communication in Cloud Environment" at International Journal of Computer Applications (0975 – 8887)
6. Eman M. Mohamed and Hatem S. Abdelkader presented "Enhanced Data Security Model for Cloud Computing" at The 8th International Conference on INFOrmatics and Systems (INFOS2012).
7. Deyan Chen and Hong Zhao presented "Data Security and Privacy Protection Issues in Cloud Computing" at IEEE 2012 International Conference on Computer Science and Electronics Engineering.
8. D. Kesavaraja, R. Balasubramanian and D. Sasireka published " Implementation of cloud data server(CDs) for providing secure service in E business" in International journal of Database Management System (IJDMS) vol-2, no-2 2010.
9. Dan Lin & Anna Squicciarini, presented "Data Protection Models for Service Provisioning in the Cloud" at SACMAT'10, 2010, Pittsburgh, Pennsylvania, USA
10. Sherif El-etriby and Eman M. Mohamed presented "Modern Encryption Techniques for Cloud Computing" at ICCIT 2012.
11. Farzad Sabahi, "Cloud computing security threats and responses" presented at Communication Software and Networks (ICCSN), 2011 IEEE 3rd International Conference
12. Jianfeng Yang and Zhibin Chen "Cloud Computing Research and Security Issues", presented at Computational Intelligence and Software Engineering (CiSE), 2010 International Conference.

Trusted Cloud Computing Cloud Networking And Cloud Computing