Task-oriented access model for secure data sharing over cloud

Cloud computing has become a prevalent technology and with its increased maturity more and more data including sensitive and non sensitive, is being centralized into it. While outsourcing the sensitive data into public cloud, its prior encryption is strongly recommended. Provisioning of encryption and existing work that guarantee security and privacy concerns on sensitive data, have removed the holdouts against cloud adoption at a large. One of the main issue with this data in cloud environment is to manage user access and its auto revocation in a controlled and flexible way. The issue becomes more complex when privacy on user access has to be ensured as well to hide additional leakage of information. For automatic revocation over cloud data, access can be bounded within certain anticipated time limit so that the access expires beyond effective time period as proposed by one of the existing system as time based proxy re-encryption. This time-oriented approach is more rigid and not a one-size-fits-all solution. In certain circumstances exact time anticipation is not an easy choice. Instead, the alternate solution could be task-oriented to restrict user beyond certain number of permissible attempts to access the data. In this paper we have proposed a system that allows authorized users to access encrypted data for predefined attempts rather pre-defined time. Our approach allows user to avail permissible attempts without time restriction and at the same time also preserves the privacy aspect of user access by concealing access limit until availed. Performance analysis revealed that the cost of operations performed are within the range of .097 to .278 $ per 1000 requests.