Outsourcing Decryption of Multi-Authority ABE Ciphertexts

The notion of multi-authority attribute based encryption was introduced by Chase in TCC 2007. In this paper, we improve Chase’s scheme to allow encryptors to determine how many attributes are required for each ciphertext from related attribute authorities. The proposed scheme can be seen as a multi-trapdoor construction. Furthermore, we apply the LMSSS to outsource the decryption of multi-authority attribute based encryption scheme for large universe. Also, the outsourcing scheme can be realized in the setting of multi-authority key-policy attribute based encryption. Both our schemes can be extended to RCCA secure ones.