Netizens with extreme privacy needs got a new tool for their cyber utility belts recently with the release of an application that lets users hide secret messages in virtually any executable computer program, without changing the program's size or affecting its operation.

The tool is called "Hydan," an old English word for the act of hiding something, and it's part of a research project by Columbia University computer science masters student Rakan El-Khalil, who showed off the program to a small group of open-source programmers and hackers gathered at the second annual CodeCon conference in San Francisco on Sunday.

Hydan is a novel development in the field of steganography -- the science of burying secret messages in seemingly innocuous content. Popular stego programs operate on image and music files, where a secret missive can be hidden without altering the content enough to be perceived by human senses. But because they contain instructions for a computer's processor, executable files are less forgiving of tampering. Improperly changing a single bit of executable code can render an application completely unusable.

[ Read more ]