With the rapid development of information technology and intelligence, there are more and more usage scenarios of graph data. Path queries have always been a hot topic of research for scholars. There are already many mature methods and ideas in the study of the path query on the plaintext graph. For the path query on graph data in the case of cloud outsourcing, it is necessary to consider both the construction of query algorithms and the protection of privacy information. The processing of graph privacy information through encryption, and then outsourcing to the cloud platform, is a common measure. The semantic‐based path query supporting multikeyword search is an extended path query method, which can improve the query function. For users, it is very troublesome to access and process the encrypted graph data. In this article, we propose a protecting‐privacy semantic‐based multikeyword path query scheme on the ciphertext graph (PSMP). Firstly, based on the principle of searchable encryption and vector operation, a secure index is constructed, and then the cloud server uses the secure index to implement path queries. This article demonstrates its security through formal analysis and verifies its effectiveness through experimental comparison and analysis. The work of this article has a certain promoting effect on the query processing and analysis of ciphertext graph data.

Efficiency, security, and flexibility are difficult to balance in a full policy hiding CP-ABE scheme. This paper creatively converts the privacy matching problem of access policy and a user’s private key to the privacy three-party set computation problem. Then the new privacy set computation problem is resolved by a message driven key generation method. Additionally, the ROBDD (Reduced Ordered Binary Decision Diagrams) is utilized to rich access structure expression and convert access policies into feasible path sets. Each feasible path is composed of attributes and these attributes are bound to the ciphertext using CP-ABE. Based on the innovative ideas mentioned above, we present a Lighten Fine-grained Access Control scheme supporting Full Policy Hidden (LFAC-FPH) that integrates data confidentiality protection, access policy rich expression but complete hiding, fine-grained access control, and lightweight terminal computing. Our scheme has three advantages: 1) High Efficiency. The proposed scheme can achieve fast privacy matching of access policies during user decryption. 2) Full Policy Hiding. The access policy bound by an owner on the ciphertext does not leak any information. Moreover, a user cannot know attributes they do not own. 3) High Flexibility. The decryption process does not require online from owners or KGC, and system attributes can be added at any time.

Proxy re-encryption (PRE) provides a promising solution for applications requiring efficient and secure ciphertext conversion, such as secure cloud data sharing. While the one with the function of ciphertext evolution is more desirable for some long-term schemes involving key update. Recently, Yao et al. constructed an identity-based conditional proxy re-encryption scheme simultaneously supporting authorization and ciphertext evolution. However, its delegated ciphertext can be re-authorized, which may cause the authorization to exceed the original delegator’s expectation. In contrast, the single-hop PRE authorization scheme may be more appropriate for systems requiring better control over authorization. In this paper, an identity-based proxy re-encryption scheme with single-hop conditional delegation and multi-hop ciphertext evolution (IBPRE-SHCD-MHCE) is proposed. Also, its description, construction, and security analysis are given. The analysis and experimental comparison results show that the proposed scheme has improved the computational efficiency and storage consumption compared with the two underlying schemes.

The arrival of cloud computing age makes data outsourcing an important and convenient application. More and more individuals and organizations outsource large amounts of graph data to the cloud computing platform (CCP) for the sake of saving cost. As the server on CCP is not completely honest and trustworthy, the outsourcing graph data are usually encrypted before they are sent to CCP. The optimal route finding on graph data is a popular operation which is frequently used in many fields. The optimal route finding with support for semantic search has stronger query capabilities, and a consumer can use similar words of graph vertices as query terms to implement optimal route finding. Due to encrypting the outsourcing graph data before they are sent to CCP, it is not easy for data customers to manipulate and further use the encrypted graph data. In this paper, we present a solution to execute privacy‐guarding optimal route finding with support for semantic search on the encrypted graph in the cloud computing scenario (PORF). We designed a scheme by building secure query index to implement optimal route finding with support for semantic search based on searchable encryption idea and stemmer mechanism. We give formal security analysis for our scheme. We also analyze the efficiency of our scheme through the experimental evaluation.

Abstract Recently, cloud computing has drawn much attention from research and industrial communities. With adoption of cloud computing, data providers can reap huge economic benefits by outsourcing their data to cloud. Because of serious privacy concerns, sensitive data should be encrypted before being outsourced. In order to share the encrypted and outsourced data, data providers need to distribute different keys to legal users. Thus, in the scenario of multiple data providers, a legal user may receive lots of keys from different providers and suffer from heavy burden from key management. In this paper, we proposed an identity‐based key management scheme, which can let a legal user only maintain a single root key regardless of the number of data providers. Based on the root key, a legal user can derive different resource keys to decrypt ciphertexts from different data providers. With the help of outsourcing decryption technique, a legal user could reduce the decryption overhead by outsourcing some decryption work to cloud. We proofed the correctness and analyzed the security of the proposed scheme, further implemented the proposed scheme, and conducted extensive experiments. The results demonstrate the efficiency and practicality of our scheme. Copyright © 2016 John Wiley & Sons, Ltd.