Abstract: With the popular of cloud computing, more and more sensitive data are stored on cloud and it can easily be shared over the Internet. At the same time, the problems of security come. To counter this problem, this paper proposes an effectual way for data shared based on CP-ABE. This encryption scheme is very applicable to fine-grained access controls of outsourced database, and can be used to solve some safety problems of cloud usage. In this paper, we use the access structure with only AND gates and make attributes as public key. Every attribute can express three different situations, including positive, negative, and irrelevant, in AND gate. In particular, It associates ciphertext with user‘s private key properties, supporting proxy re-encryption. Based on the above, this proposed scheme can also have high flexibility in representing access control policy and reduce the burden of authorized agency. In addition, it implemented instant revoking of user properties and efficient decryption.

Key words: Attribute-based Encryption (ABE), access control, key revocation