Secure data sharing through additive similarity based ElGamal like encryption

Cloud computing can be stated as the set of hardware and software resources and services which are offered through the internet for all users on their demand basis by cloud service providers. Data as a Service is rising as a famous service model in which data and information stored in the cloud is made available to customers based on their access policies. Data security and privacy is a major security challenges in the cloud. Encrypting the data and information by the owner and then outsourcing the details to the cloud seems to be good but it leads some potential efficiency problem. When the data owner reneges some of the user's access rights, the outsourced encrypted data is not secured. An efficiently implemented and secured data sharing by using the asymmetric key encryption algorithm called additive similarity based encryption with proxy re encryption method that prevents the outflow of illegal data. Homomorphism enables querying, retrieving and operating on encrypted information in the cloud and it allows data to be processed by third party without breaking the confidentiality. The proposed method is implemented using CloudSim and JDK to ensure the privacy of the data owner in the cloud and also from the approved users.