K-Anonymous Location-Based Fine-Grained Access Control For Mobile Cloud

Mobile cloud computing is a revolutionary computing paradigm for mobile application which enables storage and computation migration from mobile users to resources rich and powerful cloud servers, but emerges various privacy concerns. Attribute based encryption is a public key encryption that ensures the security of stored data in the cloud and provides fine grained access control using defined policies and constraints. Location of a device is one of the contextual policies which is used to improve data security, authenticate users and provide access to services and useful information for mobile users. However, unlike other policies and attributes used in attribute based encryption, location of mobile users are dynamic. In this paper, we investigate providing Location Based Services (LBS) for attribute based access control in mobile cloud. More specifically, we propose a multi-authority attribute based access control scheme and protect users privacy against malicious authorities. The proposed scheme uses dynamic location of a mobile user as contextual information about that user, employs coarse location as an attribute in attribute based encryption to achieve K-anonymity, and filters the returned results for more accuracy. The attribute based encryption is integrated with proxy re-encryption to outsource the computation to a cloud server with "unlimited" computational power. The proposed scheme achieves efficiency by reducing computational cost on resource-constrained mobile users.