9. Authorship Analysis

Following the tragic events of September 11, 2001, researchers have been called upon to assume a larger role in the preservation of public safety and national security. One of the major challenges facing the intelligence and security community is monitoring of online communication mediums that are commonly used by terrorist groups. In this chapter, we addressed the online anonymity problem by successfully applying authorship analysis to English and Arabic extremist group web forum messages. The performance impact of different feature categories and techniques was evaluated across both languages. In order to facilitate enhanced writing style identification, a comprehensive list of online authorship features was incorporated. Additionally, an Arabic language model was created by adopting specific features and techniques to deal with the challenging linguistic characteristics of Arabic, including an elongation filter and a root clustering algorithm. A series of experiments were conducted to evaluate the efficacy of our models with results indicating a high level of success. Finally, a comparison of the English and Arabic language models and messages was made to aid the research community’s understanding of the dynamics of these group’s authorship tendencies.