Multi-Authority Attribute-Based Encryption Scheme with Privacy Protection

Attribute based encryption (ABE) is a new cryptographic technique which guarantees fine-grained access control of outsourced encrypted data in the cloud. In order to protect the users’ sensitive information in the cloud, a multi-authority attribute based encryption (MA-ABE) scheme with privacy protection is proposed. In the scheme, the users’ attribute is divided into two parts: the attribute name and the attribute value. The value of user’s attributes would be hidden in the access structure to prevent from revealing to any third parties, so the users’ privacy will be effectively preserved. In addition, the attribute name is used to construct the access structure, and the length of our ciphertext is associated with the number of attribute name which belongs to the access policy, rather than the all attributes in the system. Besides, the scheme is secure against chosen plaintext attack under the decision bilinear Diffie-Hellman (DBDH) assumption in the standard model. Compared with the existing related schemes, the size of ciphertext and users’ secret key in the scheme are all reduced, and the lower computing cost and storage cost makes the scheme more effective in the practical application, especially the condition in which the scale of user attributes is far smaller than the scale of system attributes.