Despite that existing data sharing systems in online social networks (OSNs) propose to encrypt data before sharing, the multiparty access control of encrypted data has become a challenging issue. In this paper, we propose a secure data sharing scheme in OSNs based on ciphertext-policy attribute-based proxy re-encryption and secret sharing. In order to protect users' sensitive data, our scheme allows users to customize access policies of their data and then outsource encrypted data to the OSNs service provider. Our scheme presents a multiparty access control model, which enables the disseminator to update the access policy of ciphertext if their attributes satisfy the existing access policy. Further, we present a partial decryption construction in which the computation overhead of user is largely reduced by delegating most of the decryption operations to the OSNs service provider. We also provide checkability on the results returned from the OSNs service provider to guarantee the correctness of partial decrypted ciphertext. Moreover, our scheme presents an efficient attribute revocation method that achieves both forward and backward secrecy. The security and performance analysis results indicate that the proposed scheme is secure and effcient in OSNs.

Improving security and efciency for encrypted data sharing in online social networks

Recently, motivated by incorporating the advantages of social networks (SNs) and mobile cloud computing (MCC), the integration of SNs and MCC receives a lot of attention from both academia and industry, since the SNs could be utilized to share the rich cloud resources and services as well as the cloud can be taken to host or enhance SNs. However, one very critical and unexplored issue when integrating SNs and MCC is evaluating the importance of users to obtain the potential influential users. In this paper, focusing on exploring the user importance evaluation issue during the integration of SNs and MCC, we propose a RFTRS scheme, which innovatively considers the Reputation, Fractal, and Topological importance in SNs as well as the Request and Storage importance in MCC to evaluate user importance. The detailed design about RFTRS is presented. A further case study is also conducted to compare the user evaluation results identified by RFTRS and other popular traditional user importance evaluation approaches in SNs. They show that new user evaluation approaches (e.g., RFTRS) when integrating SNs and MCC are needed.

An evaluation of user importance when integrating social networks and mobile cloud computing

Privacy-Preserving Data Mining (PPDM) allows one to discover hidden patterns from many sources of databases while maintaining the privacy of data. Since its inception in two pioneering work by Agrawal [AS00] and Lindell [LP00], PPDM has attracted much attention from the research community. There have been a variety of secure protocols from association rule mining to classification to clustering. There are two major approaches in PPDM: randomization and secure multi-party computation. The former is based on statistical properties to add noise to the original values to hide sensitive data. The latter makes use of encryption techniques to prevent adversaries from seeing original data. Our proposed methods in this thesis follow the second approach. We first introduce an efficient privacy-preserving protocol to compute scalar product for multiple parties called CSSP. The protocol is designed using caching techniques thanks to homomorphic multiplicative cryptosystems. When applying to association rule mining problems, CSSP outperforms existing work in term of running time while maintaining the same level of security. Since data is always updated, there is a need for protocols to adapt with the changes. With this purpose, we propose an incremental privacy preserving data mining protocol for association rule mining that allows parties to perform mining tasks on updated data instead of entire data. The protocol, called INCRE, scans old databases at most once, and therefore reducing computation overheads. We also conduct experiments to show the efficiency of the protocol over the existing methods.

/pdf/speeding-up-privacy-preserving-data-mining-techniques-egoz1wuwkf.pdf

Speeding up privacy preserving data mining techniques

Encrypted data sharing with multi-owner based on digital rights management in online social networks

Although current online social networks (OSNs) schemes propose to encrypt data before sharing, the enforcement of access policies over encrypted data has become a challenging task, and the OSNs currently do not provide any mechanism to allow users to update access policies. In this paper, we propose a ciphertext sharing scheme in cloudbased OSNs, which allows the users to outsource encrypted data to the OSNs service provider for sharing. In order to meet the authorization requirement, we present a multiparty access control model based on ciphertext-policy attribute-based proxy reencryption, which enables the access control of encrypted data associated with multiple users. On the basis of ciphertext-policy attribute-based encryption, the owners can customize the access policy of their own data. Based on proxy re-encryption, the disseminators such as friends and group members can further customize the access policy of the owners’ data upon existing access policy. Besides, we achieve immediate user revocation based on secret sharing without issuing new attribute secret keys to unrevoked users. The security and performance analysis show that our proposed scheme is secure, efficient and practical.

/pdf/multiparty-access-control-of-ciphertext-sharing-in-cloud-7krs5gu320.pdf

Multiparty Access Control of Ciphertext Sharing in Cloud-Based Online Social Networks

In this paper, we propose a new framework for secure sharing data on cloud-based social networks. The framework satisfies the security based on the combination of symmetric and asymmetric cryptosystems. In addition, dynamic one-time used symmetric cryptographic keys and proxy re-encryption schemes are used in this framework to improve the security of cryptographic systems. By using this framework, the data is being shared between users in much more secure way.

Nguyen Manh Dien

Papers

A new framework for secure sharing data on cloud-based social networks