Blockchain-Based Multi-Authority Ciphertext-Policy Attribute-Based Encryption Scheme with Equality Test
Aiming at the problems of ciphertext retrieval classification difficulty and dependence on trusted third party in the ciphertext-policy attribute-based encryption schemes within cloud environment,a blockchain-based multi-authority ci-phertext-policy attribute-based encryption scheme with equality test is proposed.The attribute-based encryption with equali-ty test technology is used to retrieve and classify ciphertexts that supports attribute-level flexible authorization,which reduc-es the computational cost of data users to decrypt duplicate data.Combined with multi-authority attribute-based encryption and blockchain technology to achieve decentralized user key generation.Meanwhile,the key is jointly distributed by differ-ent authorized institutions can effectively resist collusive attacks by users and attribute authorization agencies.Blockchain and smart contract technology are introduced to eliminate the dependence of trusted cloud servers in the outsourcing decryp-tion,data storage and equivalence test operation in the existing ciphertext-policy attribute-based encryption with equality test-ing schemes.Outsourced server is used to perform part of the decryption computation,which reduces the user's local calcula-tion overhead.The original data hash and verification parameters are uploaded to the blockchain,which ensures the correct-ness of the outsourcing server's decryption results and the integrity of cloud data.Under the random oracle model,the one-way property of the proposed scheme under chosen-ciphertext attack is proved based on the decision q-parallel BDHE hard problem.Compared with similar schemes,the proposed scheme supports more security properties and has lower computa-tional overhead.
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