Advanced Attribute-Based Key Management for Mobile Devices in Hybrid Clouds

Mobile cloud computing requires the efficient approach to access the outsourced data in public clouds due to resource scarceness of mobile devices. To this end, the outsourced data should be protected efficiently from being accessed in plaintext by unauthorized users and public clouds. User revocation should be appropriately managed to guarantee backward secrecy, collusion resistance, and key freshness. In this paper, we present AKMD (Advanced Attribute-based Key Management for Mobile Devices in Hybrid Clouds), an improved key management in hybrid clouds using cipher text-policy attribute-based encryption to allow only authorized users to access the outsourced data stored in public clouds while guaranteeing the efficiency by delegating the key management tasks to private clouds. We introduce new two procedures to handle user revocations, rekey of data encryption keys and policy renewal to support the backward secrecy and key freshness. Our implementation and analysis show that AKMD improves efficiency in security computations and key storage space for mobile devices and guarantees the improved security.