Research on the Update Method of CP-ABE Access Control Strategy Based on Smart Contract

Abstract

The CP-ABE access control method based on blockchain realizes fine-grained access control of data and ensures the storage of ciphertext security. However, there are some problems in updating the access control policy. For example, the blockchain cannot be used as ample data storage. The ciphertext size increases with the number of attributes and the complexity of the access control policy, and the CP-ABE based on bilinear mapping is expensive to calculate. Therefore, this paper proposes dividing the ciphertext into data-related ciphertext and policy-related ciphertext, which are stored in blockchain and IPFS. It is worth noting that this paper uses the RSA-based CP-ABE encryption method, which can effectively reduce the computational cost of encryption and decryption and achieve a constant ciphertext size. In addition, we also systematically analyze and compare the advantages and costs generated by CP-ABE based on bilinear mapping and CP-ABE based on RSA. Through experimental analysis, security analysis, and formal analysis, compared with the existing access control policy update methods, the scheme proposed in this paper shows better performance when frequently updating the access control policy.