Privacy-Preserving Decentralized Key-Policy Attribute-Based Encryption Schemes with Fast Decryption

Abstract

We present an efficient decentralized Attribute-Based Encryption (ABE) that supports any Monotone Access Structure (MAS) with faster decryption capability in the key-policy setting. We further extend our MAS construction to Non-Monotone Access Structure (nonMAS) in order to support negative attributes. A notable advantage of our nonMAS construction is that the computation cost during encryption and decryption, and the size of ciphertext are linear to the number of authorities involved in the system, not to the number of attributes used in the respective process unlike existing schemes. In addition, our schemes provide user privacy, enabling any user to obtain secret keys without disclosing its unique identity to the authorities. The security reduction of both the schemes rely on the decisional Bilinear Diffie-Hellman Exponent problem.