04-08-2012, 04:06 PM
Steganography-An efficient data hiding technique
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ABSTRACT
Steganography is the art of hiding the fact that communication is taking place, by hiding information in other information. Many different carrier file formats can be used, but digital images are the most popular because of their frequency on the Internet. For hiding secret information in images, there exists a large variety of steganographic techniques some are more complex than others and all of them have respective strong and weak points. Different applications have different requirements of the steganography technique used.
For example, some applications may require absolute invisibility of the secret information, while others require a larger secret message to be hidden. This paper intends to give an overview of image steganography, its uses and techniques. It also attempts to identify the requirements of a good steganographic algorithm and briefly reflects on which steganographic techniques are more suitable for which applications.
Steganography is the technique of hiding confidential information within any media. Steganography is often confused with cryptography because the two are similar in the way that they both are used to protect confidential information. The difference between the two is in the appearance in the processed output; the output of steganography operation is not apparently visible but in cryptography the output is scrambled so that it can draw attention. Steganlysis is process to detect of presence of steganography. In this article we have tried to elucidate the different approaches towards implementation of steganography using ’multimedia file.
INTRODUCTION
Since the rise of the Internet one of the most important factors of information technology and communication has been the security of information. Cryptography was created as a technique for securing the secrecy of communication and many different methods have been developed to encrypt and decrypt data in order to keep the message secret. Unfortunately it is sometimes not enough to keep the contents of a message secret, it may also be necessary to keep the existence of the message secret. The technique used to implement this, is called steganography.
Though security is nothing new, the way that security has become a part of our daily lives today is unprecedented. From pass codes that we use to enter our own highly secure homes, to retina-scanning technology that identifies us as we enter our office buildings, to scanners in airports, we have made security technology as much a part of our daily lives as the telephone or automobile.We are also surrounded by a world of secret communication, where people of all types are transmitting information as innocent as an encrypted credit card number to an online store and as insidious as a terrorist plot to hijackers. The schemes that make secret communication possible are not new. Julius Caesar used cryptography to encode political directives. Steganography (commonly referred to as stego), the art of hidden writing, has also been used for generations. But the intersection of these schemes with the pervasive use of the Internet, highspeed computer and transmission technology, and our current world political climate makes this a unique moment in history for covert communication.
History
The earliest recordings of Steganography were by the Greek historian Herodotus in his chronicles known as "Histories" and date back to around 440 BC. Herodotus recorded two stories of Steganographic techniques during this time in Greece. The first stated that King
Darius of Susa shaved the head of one of his prisoners and wrote a secret message on his scalp.
When the prisoner’s hair grew back, he was sent to the Kings son in law Aristogoras in Miletus undetected. The second story also came from Herodotus, which claims that a soldier named Demeratus needed to send a message to Sparta that Xerxes intended to invade Greece. Back then, the writing medium was text written on wax-covered tablets. Demeratus removed the wax from the tablet, wrote the secret message on the underlying wood, recovered the tablet with wax to make it appear as a blank tablet and finally sent the document without being detected.Romans used invisible inks, which were based on natural substances such as fruit juices and milk. This was accomplished by heating the hidden text, thus revealing its contents.
Invisible inks have become much more advanced and are still in limited use today.
During the 15th and 16th centuries, many writers including Johannes Trithemius (author of
Steganographia) and Gaspari Schotti (author or Steganographica) wrote on Steganagraphic
techniques such as coding techniques for text, invisible inks, and incorporating hidden messages in music.
The Ancient Steganography
The word Steganography is originally made up of two Greek words which mean “Covered Writing”. It hasbeen used in various forms for thousands of years. In the5th century BC Histaiacus shaved a slave’s head, tattooed a message on his skull and was dispatched with
the message after his hair grew back [1, 2, 3, 4]. In Saudi Arabia at the king Abdulaziz City of Science and Technology, a project was initiated to translate into English some ancient Arabic manuscriptson secret writing which are believed to have been written 1200 years ago. Some of these manuscripts were found in Turkey and Germany . 500 years ago, the Italian
mathematician Jérôme Cardan reinvented a Chinese ancient method of secret writing, its scenario goes as follows: A paper mask with holes is shared among two parties, this mask is placed over a blank paper and the sender writes his secret message through the holes then takes the mask off and fills the blanks so that the letter appears as an innocuous text. In more recent history, the Nazis invented several Steganographic methods during WWII such as
Microdots, invisible ink and null ciphers.
As an example of the latter a message sent by a Nazi spy that read: “Apparently neutral protest is thoroughly discounted and ignored. Isman hard hit. Blockade issue affects pretext for embargo on by-products, ejecting suets and vegetable oils.. Using the 2nd letter from each word the secret message reveals: .Pershing sails from NY June 1.