Encryption Techniques to Ensure Data Confidentiality in Cloud

Cloud computing is proving to be a beneficial model for all types of users as it enables anyone to share and make use of the available pool of resources and get the desired services online. It reduces the operational and maintenance costs since the user needs to pay for what he has used. Databases and applications are moved to the cloud and stored in large data stores of the cloud service provider which may be insecure or untrustworthy. End users want to know the location of data being stored and who have control over the information apart from the owners. They particularly want the data to be secured from unintentional or illegal access even by the service providers. As the data are stored in geographically dispersed area, the data is vulnerable. The most important concern is that data confidentiality is to be attained while data is stored or in transit. To provide confidentiality, initially cryptographic approaches were used that disclose the keys needed for decryption only to the authorized users. But in the cloud, the adopted encryption schemes should support fine-grained access control, high performance, scalability as well as full delegation. In order to share valuable data confidentially on the cloud in a secured way, various encryption techniques are available starting from Identity-Based Encryption, Attribute-Based Encryption, Hierarchical Attribute-Based Encryption, Identity-Based Broadcast Encryption, Searchable Encryption, Homomorphic Encryption, Fully Homomorphic Encryption and so on. This paper analyses some of the recent and popular encryption techniques and discusses the issues related to them.