The Latest Trends in Steganography.

Steganography, the art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient suspects the existence of the message. It is based on invisible communication in which the secret message is shared wither any other by hiding in the cover file. Herodotus’s histories describes the earliest type of steganography& states, “The slave’s head was shaved and then a Tattoo was inscribed on the scalp. When the slave’s hair had grown back over the hidden tattoo, the slave was sent to the receiver. The recipient once again shaved the slave’s head and retrieved the message”. The word steganography is derived from the Greek words “stegos” meaning “cover” and “grafia” meaning “writing” defining it as “covered writing”

All steganography techniques use Cover-Object and Stego-Object. Cover-object refers to the object used as the carrier to embed the message into it. In the above example the slave’s head (without tattoo) is the cover object. In modern context Images, file systems, audio, video, HTML pages, word documents and email-spam can be used as cover objects. Almost all digital file formats can be used for steganography, but the formats that are more suitable are those with a high degree of redundancy. Redundancy can be defined as the bits of an object that provide accuracy far greater than necessary for the object’s use and display. The redundant bits of an object are those bits that can be altered without the alteration being detected easily. Image and audio files especially comply with this requirement.

Hiding information in text is historically the most important method of steganography. An obvious method was to hide a secret message in every nth letter of every word of a text message. It is only since the beginning of the Internet and all the different digital file formats that is has decreased in importance. Text steganography using digital files is not used very often since text files have a very small amount of redundant data. Given the proliferation of digital images, especially on the Internet, and given the large amount of redundant bits present in the digital representation of an image, images are the most popular cover objects for steganography. To hide information in audio files similar techniques are used as for image files. One different technique unique to audio steganography is masking, which exploits the properties of the human ear to hide information unnoticeably. A faint, but audible, sound becomes inaudible in the presence of another louder audible sound. This property creates a channel in which to hide information. Steganography is widely used in Defense, Intelligence and other departments where a secret message is transmitted or exchanged so there is a great scope for steganography in current & future job market.