Biblio

Smart grid has improved the security, efficiency of the power system and balanced the supply and demand by intelligent management, which enhanced stability and reliability of power grid. The key point to achieve them is real-time data and consumption data sharing by using fine-grained policies. But it will bring the leakage of the privacy of the users and the loss of data control rights of the data owner. The reported solutions can not give the best trade-off among the privacy protection, control over the data shared and confidentiality. In addition, they can not solve the problems of large computation overhead and dynamic management such as users' revocation. This paper aims at these problems and proposes a decentralized attribute-based data sharing scheme. The proposed scheme ensures the secure sharing of data while removing the central authority and hiding user's identity information. It uses attribute-based signcryption (ABSC) to achieve data confidentiality and authentication. Under this model, attribute-based encryption gives the access policies for users and keeps the data confidentiality, and the attribute-based signature is used for authentication of the primary ciphertext-integrity. It is more efficient than "encrypt and then sign" or "sign and then encrypt". In addition, the proposed scheme enables user's revocation and public verifiability. Under the random oracle model, the security and the unforgeability against adaptive chosen message attack are demonstrated.

Decentralized attribute-based encryption (ABE) is an efficient and flexible multi-authority attribute-based encryption system, since it does not requires the central authority and does not need to cooperate among the authorities for creating public parameters. Unfortunately, recent works show that the reality of the privacy preserving and security in almost well-known decentralized key policy ABE (KP-ABE) schemes are doubtful. How to construct a decentralized KP-ABE with the privacy-preserving and user collusion avoidance is still a challenging problem. Most recently, Y. Rahulamathavam et al. proposed a decentralized KP ABE scheme to try avoiding user collusion and preserving the user's privacy. However, we exploit the vulnerability of their scheme in this paper at first and present a collusion attack on their decentralized KP-ABE scheme. The attack shows the user collusion cannot be avoided. Subsequently, a new privacy-preserving decentralized KP-ABE is proposed. The proposed scheme avoids the linear attacks at present and achieves the user collusion avoidance. We also show that the security of the proposed scheme is reduced to decisional bilinear Diffie-Hellman assumption. Finally, numerical experiments demonstrate the efficiency and validity of the proposed scheme.