By N. Poh, W. Albukhanajer, G. Qadir, A. Natour, S. Yahaya, and H. Wang
In a spirit of collaboration and industrial activities of the Department of Computing, the MSF research group (an active research group led by Prof Anthony TS Ho), has received an invitation to visit the MET Police lab. The Multimedia Security and Forensics (MSF) research activities include processing all forms of digital media such as from data hiding (Steganography and Steganalysis) and content verification (via watermarking) to tampering detection and authentication (via biometrics and CAPTCHA). Many of the techniques investigated are relevant to the MET police which focuses on digital forensics. They work with all sorts of digital data obtained from crime scenes such as CCTV footage, intercepted voice recordings, damaged mobile phone and other portable devices.
We may be all too familiar with the American TV series called CSI or Crime Scene Investigation but learning first-hand how investigation is actually done is quite a different experience. For instance, it may appear to be easy for a brilliant officer to spot an event in a movie, or that there is an AI software that ploughs through the data to come up with a piece of evidence which is then magically magnified to obtain a crystal clear image (Robocop did that!). In reality, one has to deploy all sorts of techniques to obtain a decent image frame from CCTV. For instance, it may be necessary to hack away standard driver software in order to download a raw video sequence so as to minimise compression artefacts. Then, images across frames need to be meticulously aligned to produce a super-resolved image. After that, it still remains a great challenge to understand the content.
The visit was very useful and rich in knowledge. It became clear that it is possible to hack into a damaged digital mobile device in order to obtain information. It takes determination and perseverance and great interest in the technical details — perhaps the qualities of a dedicated hacker — in order to recover data stored in the device.
All in all, the visit was extremely beneficial to our group. It reminds us that the techniques we develop can help fight or reduce crimes. Apart from performance, usability and robustness of a technique or a piece of software are also important considerations in practice.