The goal of this special issue is to collate a selection of representative research articles that were primarily presented at the 8th International Conference on Network and System Security (NSS 2014). This annual conference brings together researchers and practitioners in the world from both academia and industry who are working on network and system security, in order to foster interaction between researchers and developers, promote an exchange of ideas, discuss future collaborations, and develop new research directions.The recent advances in technology result in an explosive growth of data available. Sources such as sensors, social networks, Internet of Things, and the Internet are generating 2.5 quintillion bytes of data every day. With the vision of extracting useful knowledge and the promise of data-driven decisionmaking, big data have been emerging as a hot topic in the research community. While the benefits of big data are clear, it also introduces technical difficulties because of its scale, complexity, and heterogeneity. This special issue presents many examples of how researchers, scholars, vendors, and practitioners are collaborating to address security and privacy research challenges.The scope of this special issue is broad and is representative of the multi-disciplinary nature of security and privacy. In addition to submissions that deal with security challenges, privacy issues, theoretical analysis, algorithms, protocols, and practical experience in the context of big data, this issue also includes articles that address practical challenges with handling large-scale data at the infrastructure level.Addressing the privacy and security concerns in big data is a central topic of this issue. Chen et al. To protect real-world data across various platforms, key management is an essential issue. Qin et al. [5] propose two lightweight group key distribution schemes to solve the problem of efficient subgroup and intergroup communication in vehicular ad hoc networks. Biometrics has been gaining popularity, due to the increasing concerns of identity fraud and the need for identity recognition. Zhou et al. [6] improve the performance of fingerprint indexing through the combination of local and global reconstructed features.In the era of big data, resources are located in a heterogeneous network environment. Fang et al.[7] address the problem of secure routing and resource allocation in cooperative cognitive radio networks based on game theory. Yang et al.[8] provide a new design on handover authentication in the wireless mesh network through an improved key predistribution.We encourage the readers to review [9,10] to gain insight into the latest innovations in the platform in the context of big data, such as fog computing [9], a new paradigm that extends cloud computing and services to the edge of the network, and private comparison in quantum cloud computing [10].We are grateful for the time and effort of the international reviewers. We deeply thank Professor Geoffrey C. Fox, the editor-in-chief, for pr...