关键词: 多权威属性基加密, 属性撤销, 访问控制, 外包计算, 区块链

Abstract: Abstract: For the problems of existing attribute-based encryption schemes, such as low efficiency of attribute revocation and difficulty in coordinating the distribution and revocation of user private keys, a blockchain-based decentralizing attribute-based encryption (BRDABE) with attribute revocation was proposed. In the BRDABE, the consensus-driven blockchain architecture was used to map the trust issue of key distribution from the attribute authority to the distributed ledger, and smart contracts were used to record the status of user attributes and data sharing, and assist the attribute authority to revoke user attributes. When revoking a user's attribute, the attribute authority used the smart contract to automatically screen out the involved data owners and non-revoked authorized users, and computed the ciphertext update key and key update key related to the revoked attribute, and made the ciphertext and key update off-chain. Then the version key and the user's global identity were embedded in the attribute private key, so that the identities in the session key ciphertext and the user's attribute private key can cancel each other when the user decrypts. Based on reasonable assumptions, the BRDABE scheme was proved to resist the collusion attack of users, and satisfied the forward and backward security of user attribute revocation. The experimental results showed that with the increase of the number of user attributes, the time of user key generation, encryption and decryption and attribute revocation increases linearly. In the case of the same number of attributes, compared with the DABE and DAC-MACS schemes, the efficiency of decryption and attribute revocation of the BRDABE scheme was improved by at least 90%. Therefore, this scheme not only improved the efficiency of attribute revocation, but also guaranteed the forward and backward security of shared data.

Key words: attribute-based encryption, attribute revocation, Access control, outsourcing computing, blockchain