Verifiable and auditable multi-authority attribute-based encryption

Attribute-based encryption (ABE) is crucial for cloud computing security as it enables fine-grained non-interactive access control and allows efficient and secure data sharing without relying on trusted third parties. Multi-authority ABE (MABE) is an improvement to traditional single-authority ABE because the former can remove the key escrow problem existed in the latter and thus is more appropriate for access control of some special applications. Recently, Zhou et al. proposed an auditable MABE (A-MABE) scheme in which the authorities are categorized into a trusted authority and several attribute authorities. For the confirmation and protection of data ownership, we propose verifiable A-MABE (VA-MABE) schemes in this paper. The additional feature of verifiability is achieved by our newly proposed zero-knowledge proof protocol which enables a data sender (i.e. data owner) to prove the ownership of the encrypted data without leaking sensitive information. Our proposed VA-MABE schemes also afford authorities the flexibility to join or exit the system with a minimal cost. Addressing concerns about centralized audit power, we incorporate technologies that decentralize this role, thereby enhancing the system's resilience.