Today’s most of small scale industries and companies are outsourcing there data over the cloud.Cloud is a infrastructure provided by the service provider to build internet application. Cloud computing is the delivery of computing as a service rather than a product, whereby shared resources, software, and information are provided to computers and other devices as a metered service over a network (typically the Internet)[2].Various commercial models are developed that can be described as “X as a service”, where X can be a hardware, software, application or storage. Various examples of cloud computing service providers are Google App Engine, Microsoft Azure, Amazon.
Cloud Computing however suffers from various security issues as data owners store their data on external servers, there have been increasing demands and concerns for data confidentiality, authentication and access control.Cloud providers have recognized the cloud security concern and are working hard to address it. In fact, cloud security is becoming a key differentiator and competitive edge between cloud providers. By applying the strongest security techniques and practices, cloud security may soon be raised far above the level that IT departments achieve using their own hardware and software. The work done proposes cryptographic access control model as shown in Figure.1 which we have considered as the system model in our work. This model mainly consist of Cloud Service Provider(CSP) and a Data Owner(DO).The
Data Owner at first uploads the data over the cloud provided by the Cloud Service Provider. This data is kept in an encrypted format as the Cloud Service Providers may not be trustworthy. Then whenever the data user requiresthere data, authentication occurs and data access is provided to valid users if the authentication is successful. This is shown in the following figure 1.Some methods of data security guarantees confidentiality, integrity and authentication, but the problem with this model is that the owner is required to be always online when the user wants to access the data. The key management between the Data Owner and Cloud Service Provider is also very difficult.