Security-Enhanced Function Privacy Attribute-Based Encryption

Attribute-based encryption is the extension of identity-based encryption. It associates ciphertext and user private key with attributes to flexibly represent access structure to achieve fine-grained access control. However, at present, most ABE schemes focus on data privacy protection, while ignoring the user's private key, which is an important part of privacy disclosure. Based on the concept of function privacy of IBE, the definition of function privacy attribute-based encryption is given. Additionally, through the analysis of the well known fuzzy identity encryption scheme, we show why the existing work does not support function privacy. To achieve the function privacy, this paper shows how to use "extract-add-combine" to transform the existing work to an security-enhanced scheme. We also present the security proof of the modified scheme.