Steganography under various media

Steganography comes from the Greek and literally mean, "Covered or secret writing". Although related to cryptography, they are not the same/Steganography's intent is to hide the existence of the message, while cryptography scrambles a message so that it cannot be understood.

Steganography is one of various data hiding techniques, which aims at transmitting a message on a channel where some other kind of information is already being transmitted. The goal of Steganography is to hide messages inside other “harmless” messages in a way that does not allow any “enemy” to even detect that there is a second secret message present/The only missing information for the “enemy” is the short easily exchangeable random number sequence, the secret key, without the secret key, the “enemy” should not have the slightest chance of even becoming suspicious that on an observed communication channel, hidden communication might take place.

In the field of steganography, some terminology has developed, The adjectives Cover, Embedded And stego were defined at the Information Hiding Workshop held in Cambridge, England. The term “cover” ’is used to describe the original, innocent message, data, audio, still, video and so on. When referring to audio signal Steganography, the cover signal is sometimes called the “host” signal.

The following formula provides a very generic description of the pieces of the steganographic process: cover_medium + hidden_data + stego_key = stego_me.