Abstract: IBE (Identity-Based Encryption) simplifies the public key and certificates management at public key infrastructure is an important alternative public key encryption. One of the main efficiency drawbacks of IBE. is the overhead computation at private key generator during user abolishment? We introduce outsourcing computation into IBE for the first time and propose a revocable identity based Encryption. In the server-aided setting. our scheme offloads most of the key generation related operations during key-issuing and key update process to an on a key update cloud service provider. leaving only a constants number of simple operations for private key generator. This goal achieved by utilizing a novel collusion-resistant technique. We exercise a hybrid private key for each user. In cloud computing systems, there are two main research problems which we studied recently such as efficient IBE revocation and security enhancement in IBE method. By considering both research problems, in this project we proposed hybrid approach to deliver both efficient revocation and enhanced security. This hybrid approach is combination of two well know security techniques such as IBE and ABE. The ABE method is combined with IBE to achieve the strong security against different threats. Along with user identity, his/her attributes like country or kind of subscription he/she has are used for further process of IBE encryption, decryption and revocation. Another problem of efficient identity revocation is further addressed by presenting the outsourcing computation into hybrid IBE (H-IBE) method at server aided settings. In H-IBE, the key generation processing’s handled during the process of key issuing and key update to the KU-CSP (key update cloud service provider) by leaving fixed number of easy processing’s for PKG as well as users to perform locally. The new collusion resistant approach is proposed in this project to achieve the efficient revocation. The practical work is performed by creating different number of cloud users for file upload and downloads processing using proposed C-IBE method.

Keywords: ABE, C-IBE, KU-CSP, PKG.