Abstract: Cloud computing is being used in every applications of web technology including web applications, mobile communication and remote data access oriented applications. This is also threatening for the information of the users of these cloud computing. Most important of the threats in Cloud computing is security of the data of the users as it is being posted over the cloud and can be manipulated, misused by the other cloud users, cloud service providers or hackers. Various researchers have worked on cloud computing security and many algorithms have been developed. Still because of rapidly changing technologies, devices and applications demand continuous work in the field of security of data over cloud. Conventionally data security is applied using encryption/decryption key management, Intrusion Detection and Prevention systems for the networks. Applications of these techniques over the cloud makes it secured but in parallel ill minded persons are also developing tools and techniques to crack these security measures. This work is providing detailed discussions on possible security threats, solutions developed by the other researchers and an integrated security solution for the same. It will use cryptography techniques, trust management and application of Intrusion Detection Systems collectively for applying the security.

Keywords: Cloud Computing, Security, Intrusion Detection System, Encryption, Decryption, Authentication, Authorization, non-repudiation.