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Probing into Digital Image Tampering
~ by Anthony FUNG, Council Member of ISFS

As Digital imaging is now common and affordable, there have been quite a few techniques proposed in combating the tampering of digital images. In 1994, scientists back in Jet propulsion Laboratory in Pasadena (NASA) has developed a solution based on public key. The digital camera computes a cryptographic hash of the image, and encrypts the hash using the private component of the key, which is built into the camera. The encrypted hash is then stored along with the digital image. Another complementary approach is to use digital time-stamping. If a forensic scientist wishes to ascertain that an image existed on or before a certain date, then a hash function of the image is submitted to a digital time-sharing service for validation. As of today, I have not observed such service provided in the community. (Full content in pdf)

Bootable CD
~ by FUNG Wai Wa, Council Member of ISFS

While IBM-PC was first introduced in early 1980's, there was no hard-disk attached to the machine: PC at that time was booted up with a floppy disk (not the 3.5" floppy disk that we are using today, but the 5.25" bigger floppy disks). In mid-1980s, the price of hard-disks had reached to a level that most people can afford. Since then, hard-disk has become an indispensable component for a microcomputer system. With high-disks, bigger applications can be supported. More memory- and disk-hungry applications are created, and a major trend started: movement from command-line applications to GUI-based applications. (Full content in pdf)