Big data has become an important topic in science, engineering, medicine, healthcare, finance, business and ultimately society itself. Big data refers to the massive amount of digital information stored or transmitted in computer systems. Approximately, 2.5 quintillion bytes of data are created every day. Almost 90% of data in the world today are created in the last two years alone. Security and privacy issues becomes more critical due to large volumes and variety, due to data hosted in large-scale cloud infrastructures, diversity of data sources and formats, streaming nature of data acquisition and high volume inter-cloud migration. In large-scale cloud infrastructures, a diversity of software platforms provides more opportunities to attackers. Traditional security mechanisms, which are usually invented for securing small-scale data, are inadequate. With a rapid growth of big data applications, it has become critical to introduce new security technology to accommodate the need of big data applications. The objective of this special issue is to capture the latest advances in this research field.