The ciphertext-policy（CP） attribute-based encryption（ABE）（CP-ABE） emergings as a promising technology for allowing users to conveniently access data in cloud computing. Unfortunately, it suffers from several drawbacks such as decryption overhead, user revocation and privacy preserving. The authors proposed a new efficient and privacy-preserving attribute-based broadcast encryption（BE）（ABBE） named EP-ABBE, that can reduce the decryption computation overhead by partial decryption, and protect user privacy by obfuscating access policy of ciphertext and user＇s attributes. Based on EP-ABBE, a secure and flexible personal data sharing scheme in cloud computing was presented, in which the data owner can enjoy the flexibly of encrypting personal data using a specified access policy together with an implicit user index set. With the proposed scheme, efficient user revocation is achieved by dropping revoked user＇s index from the user index set, which is with very low computation cost. Moreover, the privacy of user can well be protected in the scheme. The security and performance analysis show that the scheme is secure, efficient and privacy-preserving.
The online social networks（OSNs） offer attractive means for social interactions and data sharing, as well as raise a number of security and privacy issues. Although current solutions propose to encrypt data before sharing, the access control of encrypted data has become a challenging task. Moreover, multiple owners may enforce different access policy to the same data because of their different privacy concerns. A digital rights management（DRM） scheme is proposed for encrypted data in OSNs. In order to protect users＇ sensitive data, the scheme allows users outsource encrypted data to the OSNs service provider for sharing and customize the access policy of their data based on ciphertext-policy attribute-based encryption. Furthermore, the scheme presents a multiparty access control model based on identity-based broadcast encryption and ciphertext-policy attribute-based proxy re-encryption, which enables multiple owners, such as tagged users who appear in a single data, customize the access policy collaboratively, and also allows the disseminators update the access policy if their attributes satisfy the existing access policy. Security analysis and comparison indicate that the proposed scheme is secure and efficient.
Cloud computing provides a convenient way of content trading and sharing. In this paper, we propose a secure and privacy-preserving digital rights management （DRM） scheme using homomorphic encryption in cloud computing. We present an efficient digital rights management framework in cloud computing, which allows content provider to outsource encrypted contents to centralized content server and allows user to consume contents with the license issued by license server. Further, we provide a secure content key distribution scheme based on additive homomorphic probabilistic public key encryption and proxy re-encryption. The provided scheme prevents malicious employees of license server from issuing the license to unauthorized user. In addition, we achieve privacy preserving by allowing users to stay anonymous towards the key server and service provider. The analysis and comparison results indicate that the proposed scheme has high efficiency and security.
Anonymous proxy signature scheme can provide the privacy protection for the proxy signer. Recently, Yu et al. proposed an anonymous proxy signature, which can be viewed as the organic combination of proxy signature and ring signature. However, the efficiency is low. In this paper, we propose an efficient and secure proxy signature with the properties of anonymity and traceability, and it is provably secure in the random oracle model. Compared with Yu et al.＇s scheme, the scheme has higher efficiency.
