Abstract: The privacy and secure access of sensitive data stored in the cloud server is important content in cloud computing security research．A secure,effective,fine-grained access control scheme in cloud computing was proposed．The ciphertext encryption employs a CP-ABE with a linear secret sharing matrix,and most of the re-encryption work is transferred to the cloud service provider,so the scheme reduces the data owner’s computational cost on the premise of security．When user attributes’ revocation occurs,the scheme introduces SD broadcast encryption technology,effectively reducing the computing and communication overheads．The analysis shows that the scheme has the data confidentiality,collusion-resistance,backward and forward secrecy．Finally the experiment result validates the high revocation efficiency of the scheme.

Key words: Access control,Cloud computing,Subset difference,Attribute-based encryption,Revocation