Biblio

Ciphertext policy attribute-based encryption (CP-ABE) is a promising cryptographic technology that provides fine-grained access control as well as data confidentiality. It enables one sender to encrypt the data for more receivers, and to specify a policy on who can decrypt the ciphertext using his/her attributes alone. However, most existing ABE schemes are constructed on bilinear maps and they cannot resist quantum attacks. In this paper, we propose a multi-authority CP-ABE (MA-CPABE) scheme on ideal lattices which is still secure in post-quantum era. On one hand, multiple attribute authorities are required when user's attributes cannot be managed by a central authority. On the other hand, compared with generic lattice, the ideal lattice has extra algebraic structure and can be used to construct more efficient cryptographic applications. By adding some virtual attributes for each authority, our scheme can support flexible threshold access policy. Security analysis shows that the proposed scheme is secure against chosen plaintext attack (CPA) in the standard model under the ring learning with errors (R-LWE) assumption.

Ciphertext policy attribute-based encryption (CP-ABE) is a promising technology that offers fine-grained access control over encrypted data. In a CP-ABE scheme, any user can decrypt the ciphertext using his secret key if his attributes satisfy the access policy embedded in the ciphertext. Since the same ciphertext can be decrypted by multiple users with their own keys, the malicious users may intentionally leak their decryption keys for financial profits. So how to trace the malicious users becomes an important issue in a CP-ABE scheme. In addition, from the practical point of view, users may leave the system due to resignation or dismissal. So user revocation is another hot issue that should be solved. In this paper, we propose a practical CP-ABE scheme. On the one hand, our scheme has the properties of traceability and large universe. On the other hand, our scheme can solve the dynamic issue of user revocation. The proposed scheme is proved selectively secure in the standard model.

There is an increasing trend for data owners to store their data in a third-party cloud server and buy the service from the cloud server to provide information to other users. To ensure confidentiality, the data is usually encrypted. Therefore, an encrypted data searching scheme with privacy preserving is of paramount importance. Predicate encryption (PE) is one of the attractive solutions due to its attribute-hiding merit. However, as cloud is not always trusted, verifying the searched results is also crucial. Firstly, a generic construction of Publicly Verifiable Predicate Encryption (PVPE) scheme is proposed to provide verification for PE. We reduce the security of PVPE to the security of PE. However, from practical point of view, to decrease the communication overhead and computation overhead, an improved PVPE is proposed with the trade-off of a small probability of error.

Device-free localization of people and objects indoors not equipped with radios is playing a critical role in many emerging applications. This paper presents a novel channel state information (CSI) pre-processing scheme that enables accurate device-free localization indoors. The basic idea is simple: CSI is sensitive to a target's location and by modelling the CSI measurements of multiple wireless links as a set of power fading based equations, the target location can be determined. However, due to rich multipaths in indoor environment, the received signal strength (RSS) or even the fine-grained CSI can not be easily modelled. We observe that even in a rich multipath environment, not all subcarriers are equally affected by multipath reflections. Our preprocessing scheme tries to identify the subcarriers not affected by multipath. Thus, CSIs on the "clean" subcarriers can be modelled and utilized for accurate localization. Extensive experiments demonstrate the effectiveness of the proposed pre-processing scheme.