Internet Forensics

Document Forgery

One advantage of using PDF files for document transfer is that they can be digitally signed and even encrypted. Signatures are overkill for most applications, but in the case of an especially sensitive document, they offer an important safeguard, preventing a malicious third party from changing the document after it has been released. This technology has been around for a number of years, but it’s not as widely used as it could be. I predict this will change over time as more cases emerge where electronic documents have been modified or forged in order to commit fraud or to embarrass, discredit, or blackmail people.

Two dramatic examples of forgery came to light during the 2004 U.S. presidential election. The fact that sophisticated forgeries were created with the sole intent of influencing public opinion is very disturbing and does not bode well for future election campaigns.

CBS News aired a story in September 2004 concerning President Bush’s service in the Texas Air National Guard in 1972. The report was based on documents that turned out to be forgeries. Even though the materials they were given were in the form of physical pieces of paper that appeared to date from that era, their electronic origin was revealed by careful analysis of the scanned documents. What gave them away was the presence of superscripts in several places. For example:

Bush wasn’t here during rating period and I don’t have any feedback from 187^th in Alabama.

Electric typewriters in ...