Online social networks (OSN) connect millions of Internet users and have played a principal role in changing the world into a new era of globalization, i.e. the online society. OSN websites, such as Facebook, Myspace, Twitter, Google+, and Flickr have become increasingly popular online applications for people to communicate information, share moments, and distribute ideas. As of 2016, the number of social network users reached 2.3 billion, which represents 68.3 percent of Internet users, and these figures are expected to increase in future years [1]. Most OSNs sites provide free storage for users to share their social content. In 2014, the data warehouse of Facebook, the largest social website, stored upwards of 300 PB of Hive data using a cloud system, with an incoming daily rate of about 600 TB user-generated content [2]. Social data is being produced faster than any organization has had to deal with before. To add to the challenge, the data is heterogeneous and produced in many formats, including plain text, document, image, video and so on. This flood of data is being generated from any number of * Corresponding author. E-mail address: L.Liu@derby.ac.uk (L. Liu). connected devices—from PCs, smart phones, tablets to streaming set-top boxes, gaming consoles, digital cameras and even fitness sensors. It is evident that we are entering into a social big data world that is urging the development of novel computing models and new types of architecture to cope with the sheer volume of data. Cloud Computing is a model for enabling ubiquitous, ondemand access to a shared pool of configurable computing resources that can be rapidly provisioned and released with minimal management effort [3]. After nearly ten years’ development, Cloud Computing is maturing and addressing barriers for big data problems. Therefore, OSN can be hosted on Cloud platforms to utilize scalable computing and storage services to process their data in either privately owned, or third-party data centers with lower infrastructure costs [4]. However, all the mainstream OSN providers have a cloud based infrastructure that is designed with a logically centralized architecture controlled by a single authority, i.e. the social network service provider. Though large websites use content distribution networks and distributed computing for performance reasons, there is still a central repository for user data. In this sense, all sensitive personal data is stored in the providers’ repository and so users are susceptible to loss of control over ownership of their privacy.