Abstract: In order to solve complex algorithm, huge communication overheads, and security loopholes for CP-ABE-based data sharing scheme problem, a decentralized data sharing system was proposed to custom read and write permissions. The CP-ABE (ciphertext policy-attribute based encryption) algorithm was combined with BLS signature algorithm for the data owner to define read or write strategy of users freely and bind the strategy with ciphertexts, making the matched user decrypt the ciphertexts personally. Experiment results show that, the data sharing scheme can outperform another in computation and communication overheads, number of system parameters, signatures length, and security level.