Even the communication cognoscenti were unaware of the meaning and importance of steganography until recently when the term made headlines, thanks to Al Qaeda. It is a marvel how this ancient branch of knowledge has been exploited for running a network of terror and a fail-proof system of covert communications.

The word steganography is derived from the Greek word steganos, which means secret or concealed, and graphy, which means writing or drawing. State of art steganography is anchored on digitized imagery and sound. It works on the principle that such files contain bits and bytes that can be altered without affecting their function, quality or meaning. These alterations are not easily discernable by human sensory system and this is true of a 16-bit sound or 24-bit imagery. This knowledge was effectively put to use by bin Laden’s outfit to send photographs, maps and sketches of targets with orders and instructions to the operatives spread over thirty countries around the globe. What could be better than to hide imagery in pornography and what could be a more suitable medium than the Internet? Besides pornographic sites, other popular sites for posting terrorist instructions are sports and technology chat rooms, and bulletin boards.          

There is no dearth of knowledge – historical, popular, or technical, on the Internet. Volumes can be downloaded if one has the desire and inclination to learn. Bin Laden has shown the world the merits of virtual learning. It is widely known that steganography is more abused than used. It is like watermarking, which has become a must for copywriting, particularly in the case of music. In the commercial world, the main driving force for steganography is protecting copyright, especially when audio, video and text have become digital, facilitating the making of near-perfect illicit copies of music, book or software. There is a sudden spurt of defence-related applications also. 

Equally significant is the usage of steganalysis, which is the art of discovering and rendering steganos useless. WetStone’s “Detection and Recovery Toolkit” which is being developed for the USAF by the Air Force Research Laboratory in New York is a case in point. They are working on evolving a set of statistical tests capable of detecting covert messages in files and transmissions. The laboratory is also engaged in development of blind stegano-detection for algorithms.    

Steganodress primarily shows up on hacker, hawala (money laundering), drug trafficking and terrorist websites. But there are cases of it appearing on commercial and news sites too, e.g. Amazon, eBay, Dow Jones, and Technology News. Although a matter of conjecture, bin Laden’s broadcasts over al Jazeera may contain “hidden messages”, “killer codes” or “anonymizers”, indicative of the prolific terminology that the art and science of steganography has spawned. These broadcasts have raised a storm of indignant protests, “Can media be a megaphone for anyone inciting murder and mayhem?” (Raja Menon in Economic Times Plainspeak, November 18, 2001 )   

Steganography is similar to cryptography, but not entirely. The former goes much beyond encryption by hiding a secret message within an ordinary message. An encrypted message is inserted into an innocuous file, like an image, by using a special algorithm. This obviates scanning and interception of the data. A code is needed to identify the secret message. There are several ways to communicate it e.g. timestamp on the message, an uncommon word in the subject or a phrase in the header. They call it a “dead drop.” 

Many products are available online. S-Tools is one of the freeware spread-steganography variety which combines both crypto and stegano attributes. The encryption is done using one of the symmetric algorithms, e.g. Data Encryption Standard (DES), Triple DES or International Data Encryption Algorithm (IDEA). The all-nettools site describes the working with S-Tools. It states, “You just drag the carrier file into the programme window, then you drag the file you want to hide, choose an algorithm and a password, and here we go!”