Biblio

At the present time, there has been a rapid increase in the variety and popularity of messaging systems such as social network messaging, text messages, email and Twitter, with users frequently exchanging messages across various platforms. Unfortunately, in amongst the legitimate messages, there is a host of illegitimate and inappropriate content - with cyber stalking, trolling and computerassisted crime all taking place. Therefore, there is a need to identify individuals using messaging systems. Stylometry is the study of linguistic features in a text which consists of verifying an author based on his writing style that consists of checking whether a target text was written or not by a specific individual author. Whilst much research has taken place within authorship verification, studies have focused upon singular platforms, often had limited datasets and restricted methodologies that have meant it is difficult to appreciate the real-world value of the approach. This paper seeks to overcome these limitations through providing an analysis of authorship verification across four common messaging systems. This approach enables a direct comparison of recognition performance and provides a basis for analyzing the feature vectors across platforms to better understand what aspects each capitalize upon in order to achieve good classification. The experiments also include an investigation into the feature vector creation, utilizing population and user-based techniques to compare and contrast performance. The experiment involved 50 participants across four common platforms with a total 13,617; 106,359; 4,539; and 6,540 samples for Twitter, SMS, Facebook, and Email achieving an Equal Error Rate (EER) of 20.16%, 7.97%, 25% and 13.11% respectively.

Insider misuse has become a major risk for many organizations. One of the most common forms of misuses is data leakage. Such threats have turned into a real challenge to overcome and mitigate. Whilst prevention is important, incidents will inevitably occur and as such attribution of the leakage is key to ensuring appropriate recourse. Although digital forensics capability has grown rapidly in the process of analyzing the digital evidences, a key barrier is often being able to associate the evidence back to an individual who leaked the data. Stolen credentials and the Trojan defense are two commonly cited arguments used to complicate the issue of attribution. Furthermore, the use of a digital certificate or user ID would only associate to the account not to the individual. This paper proposes a more proactive model whereby a user's biometric information is transparently captured (during normal interactions) and embedding within the digital objects they interact with (thereby providing a direct link between the last user using any document or object). An investigation into the possibility of embedding individuals' biometric signals into image files is presented, with a particular focus upon the ability to recover the biometric information under varying degrees of modification attack. The experimental results show that even when the watermarked object is significantly modified (e.g. only 25% of the image is available) it is still possible to recover those embedded biometric information.