CCA-Secure Type-based Proxy Re-encryption with Invisible Proxy

Proxy re-encryption is a useful cryptographic primitive, which allows a proxy to transform a ciphertext for Alice to another ciphertext of the same plaintext for Bob. Type-based proxy re-encryption is a specific kind of proxy re-encryption, where the proxy is restricted to transform only a subset of Alice's ciphertexts. This restriction is very useful in the situation where the fine-grained transformation is required. Some applications of type-based proxy re-encryption require that the underlying scheme simultaneously achieves CCA Security and Invisible Proxy. However, to the best of our knowledge, no such scheme has been proposed. In this paper, we propose the first type-based proxy re-encryption scheme that satisfies both requirements. The CCA security proof of our proposal is given in the random oracle model based on the decisional bilinear Diffie-Hellman (DBDH) assumption, extended decisional bilinear Diffie-Hellman inversion (eDBDHI) assumption, and extended decisional linear (eDL) assumption. Furthermore, our proposal holds the invisible proxy requirement unconditionally.