A Novel Privacy-Preserving Decentralized Ciphertext-Policy Attribute-Based Encryption with Anonymous Key Generation

A privacy-preserving decentralized ciphertext-policy attribute-based encryption (CP-ABE) scheme is a variant of the multi-authority attribute-based encryption schemes where it requires neither a central authority nor cooperation among authorities for issuing secret keys. It also featured the privacy-preserving and resisting user collusion. However, previous privacy-preserving decentralized CP-ABE schemes can only hide user’s partial information, such as global identifier (GID), but user’s attribute information leaked to the authority may be sensitive which will lead to privacy disclosure. To overcome this shortcoming, we propose an improved privacy-preserving decentralized CP-ABE scheme with anonymous key generation protocol, where it can prevent authorities from learning any information about user’s both GID and attributes. Theoretical analysis and simulation results demonstrate that the proposed scheme is secure and efficient. In the standard model, its security is reduced to a standard decisional bilinear Diffie-Hellman complexity assumption.