Abstract: Cloud computing has evolved as one of the most promising technologies as it has the potential to transform the traditional way of computing. It is a technology in which the resources are relying on the Internet and one can use it on pay per use modus operandi. Cloud computing enables the provisioning of these resources on demand in the form of service. Now days everyone uses cloud services for data outsourcing and sharing with. So security of data becomes important issue in cloud computing. Data should be secure and sharing of data should be efficient. To conserve the confidential data of user against untrusted servers, existing solutions generally apply cryptographic methods and reveal data decryption keys only to authentic users. However, doing this process, these solutions obligatory introduce a heavy computation overhead on the data holder for key dispensation and data management. Here we proposed an SDOP (secure data outsourcing protocol) approach for data outsourcing onto the cloud and reduced the heavy computation overhead on the data holder. In our proposed work we used chaotic standard map with proxy re-encryption (paring free unidirectional proxy re-encryption scheme) to provide fast and easy data sharing. By using chaotic standard map we are reducing the calculation overhead, while proxy re-encryption (PRE) makes flexible and easy data outsourcing. On comparing existing EFADS approach with our proposed approach we found that our proposed approach efficient than existing data sharing approach.

Keywords: Cloud computing, Proxy Re-Encryption, EFADS.