Cryptography, Cryptology, and Steganography – Term Definition

According to historical records, classified message exchanges date back to several centuries B.C.  Specifically to the Ancient Greek civilization; it is documented, for instance, during the Greco-Persian wars. The entire goal back then was to prevent by any means an unauthorized person, often the enemy, from viewing the message contents.  True science working with message encoding did not come into existence until the arrival of encoding machines, especially computer technology, and, for practical reasons, it was soon divided into several independent subject fields. In order to understand commonly used terms in these fields, let us give you a more detailed description of each field. First of all, one more term:

Message. At present day, a message is usually defined as any binar sequence, thus a series of zeros and ones. One possible message example includes chains in which each set of eight binary numbers is assigned a specific alphanumeric character (letter, numeral), e.g. as in files produced by text editors. They are not, however, the only possible messages; a message in the cryptology sense can be an email, photograph, video or even an executable application.

Steganography is therefore a field that focuses on ingenious message concealing without encoding its contents. The best known example of applied steganography today is entering bits (ones or zeros) in file areas including an image where the image change (e.g. from zero to one) is invisible or barely visible to the naked eye (e.g. a change in one point’s shade by 1:16777216).

Cryptography is a field that does its “own” encoding, i.e. explores methods to convert the original message contents (and the so-called key, the meaning of which we will explain in more detail in future articles) into different (again, within the general binary plane) contents. At the same time, it strives to make decoding the original contents from the new contents without the knowledge of the applied method or key as difficult as possible.

Cryptology is on the other hand cryptography’s “eternal rival”. It explores methods needed to break the encoded message as fast as possible, i.e. to decode its original contents.  Cryptology looks for mathematical “tricks” that exploit certain mathematical weaknesses of the used cryptograhic method, however, applied cryptology additionally uses a vast number of other, non-mathematical methods. These may include technical tricks (e.g. monitoring which circuit sections heat up more than the others, and thus deducing the contents of the encoded message being sent) or psychological tricks (e.g. various forms of popular “phishing”).

We will conclude with an anecdote: It has been suggested that some free servers specializing in “delicate” matters are run (and funded) for undercover communication purposes, based on steganographic message concealing within individual images, by organizations like Al-Qaeda or other countries’ intelligence services . Naturally, it is difficult to verify such claims due to the fact that all involved cover up any information on this topic.