The boom of the internet and the explosion of new technologies have brought with them new challenges and thus new connotations of privacy. Clearly, when people deal with e-government and e-business, they do not only need the right to be let alone, but also to be let in secret. Not only do they need freedom of movement, but also to be assured of the secrecy of their information. Solove [6] has critiqued traditional definitions of privacy and argued that they do not address privacy issues created by new online technologies. Austin [7] also asserts: “[w]e do need to sharpen and deepen our understanding of traditional concerns regarding privacy in order to respond to these new situations”.

The relationship between privacy and the use of SNS is subtle. Generally, people would like personal information to be known by a small circle of close friends and family, and not by total strangers. In some instances, people choose to reveal particular personal information to strangers, but choose not to share it with people who know them well [8], [3]. In either case, users’ information disclosure can be helpful to other users, companies and third parties. Private information is particularly valuable when the information of many people in a group is gathered on SNS [9] and aggregated.

There are two main methods of information gathering: (i) an information leak based on privacy disclosure; and (ii) an information leak based on attack techniques. Privacy disclosure refers to those information users who voluntarily publish their personal information online. This data may be contained in profiles and information exchanged between one or more people. Attack techniques steal private information that users wish to keep secret.