A Limited Proxy Re-encryption with Keyword Search for Data Access Control in Cloud Computing

In this paper, we introduce a new concept of limited proxy re-encryption with keyword search (LPREKS) for fine-grained data access control in cloud computing, which combines the function of limited proxy re-encryption (LPRE) and that of public key encryption with keyword search (PEKS). However, an LPREKS scheme cannot be obtained by directly combining those two schemes since the resulting scheme is no longer proven secure in our security model. Our scheme is proven semantically secure under the modified Bilinear Diffie-Hellman (mBDH) assumption and the

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-Decisional Bilinear Diffie-Hellman inversion (

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-DBDHI) assumption in the random oracle model.

Our proposal realizes three desired situations as follows: (1) the proxy cloud server can re-encrypt the delegated data containing some keyword which matches the trapdoor from delegatee, (2) the proxy can only re-encrypt a limited number of delegated data to the delegatee; otherwise, the private key of the proxy will be exposed, and (3) the proxy cloud server learns nothing about the contents of data and keyword.