LAUSR

Digital certificate validation associated with traditional public key cryptosystems make it impractical in real-world environments due to their storage cost. The identity-based cryptosystems have been proven advantageous as they do not require any digital certificate validation and hence their storage. Due to the key escrow, user slandering and secure key issuing problems, IBE adoption is limited to the small networks only. The existing solutions either lose the identity-based feature or require high computation cost. In this paper, we propose a mechanism to generate the user’s private key in which we mitigate the trust on single PKG by replacing it with single semi-trusted key generation center (KGC), which authenticates the user and provide the partial private key and multiple cloud privacy centers (CPCs), which protect the user’s private key with their secret keys. In order to reduce the computation cost to generate the user’s private key, the maximum computations are offloaded to the CPCs, and only constant (very less) number of operations are run on the KGC. We use the ECC-based blind technique to secure the communication over a public channel. Using the proposed escrow-free private key generation mechanism, we design an identity based encryption scheme, which is semantically secured against IND-ID-CCA attack assuming BDH problem.