Identity based Proxy Re-Encryption using Forward Security in Cloud Framework

Abstract

The public key and certificate management in Public Key Infrastructure (PKI) is simplified by an Identity based encryption (IBE) is an important substitute to public key encryption. The main drawback of IBE is the overhead computation in Private Key Generator (PKG) during user revocation. Proficient revocation has been well considered in traditional PKI setting, but the burdensome management of certificates is precisely the trouble that IBE strives to lighten. In this paper, aiming at tackling the important issue of identity revocation, we are introducing the outsourcing computation into IBE and suggest a revocable IBE scheme should be added in the server-aided setting. Our proposed scheme delivers most of the key generation related operations i.e. key-issuing and Key update processes are performed by Key Update Cloud Service Provider, leaving only a fixed number of simple operations for PKG and users to perform locally. By utilizing a novel collusion-resistant technique, this goal is achieved: we make use of a hybrid private key for each user, in which an AND gate is drawn in to attach and bound the identity component and the time component. In addition, we propose another technique which is verifiable secure under the recently formulized Refereed Delegation of Computation model. To end with, we provide extensive experimental results to reveal the effectiveness of our proposed construction.