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Friday, 2 February 2018

Stego Hider

Stego Hider

Steganography is the art  of hiding information. There are a large number of Steganographic methods used in different applications. It is extensively used in Digital Water marking, communication within closed community with additional degrees of security. An attempt is being made to implement a new technique , entitled “Steganographic Application Tool”, for image encoding in steganography. It provides more security for data transfer on Internet and other networks. Our intention is to hide the existence of the message; While Cryptography scrambles a message so that it can not be understood.
Using Steganography a secret message can be transmitted without the fact of the transmission being discovered. This hiding of data can be done in three different media such as text, image and audio files. Though there are variety of image formats to implement the algorithms used in this system, we use the JPEG format to embed the Plain text as it contains the compressed image format. In this technique, firstly the pixels values (RGB values) of the image in which the plain text is to be embedded are extracted. The bits of the plain text into the two LSB bits of the RGB values in the image. The transparency bits of the pixels are not disturbed. The fact that we are embedding the plain text into the two LSB bits enables the recipient to get the original image without any distortions. In order to provide more security, we are first encrypting the message using DES algorithm and then cipher text as the input to our technique and the same message will be extracted and decrypted at the receiver end.
Steganography is really interesting subject and the applications using Steganography are increasing day-by-day. A number of algorithms were developed and implemented to achieve Steganography in images and audio. Many new algorithms are coming and each of them uses a unique method of making life of a Steg-Analyst more miserable everyday.
Introduction to Steganography:
Steganography deals with information hiding, as opposed to encryption. The word Steganography or Stego as it is often referred to in the IT community, literally means, "covered writing" which is derived from the Greek language. Steganography is defined as the art and science of communicating in a way which hides the existence of the communication.
The objective of steganography is to send a message through some innocuous carrier to a receiver while preventing anyone else from knowing that a message is being sent at all. Computer based steganography allows changes to be made to what are known as digital carriers such as images or sounds. The changes represent the hidden message, but result if successful in no discernible change to the carrier.
Cryptography and steganography are different. Cryptographic techniques can be used to scramble a message so that if it is discovered it cannot be read. If a cryptographic message is discovered it is generally known to be a piece of hidden information (anyone intercepting it will be suspicious) but it is scrambled so that it is difficult or impossible to understand and de-code. Steganography hides the very existence of a message so that if successful it generally attracts no suspicion at all.
Using steganography, information can be hidden in carriers such as images, audio files, text files, videos and data transmissions. When the message is hidden in the carrier a stego-carrier is formed for example a stego-image. Hopefully it will be perceived to be as close as possible to the original carrier or cover image by the human senses. Images are the most widespread carrier medium. They are used for steganography in the following way. The message may firstly be encrypted. The sender (or embedder) embeds the secret message to be sent into a graphic file (the cover image or the carrier). This results in the production of what is called a stego-image. The stego-image is then transmitted to the recipient. The recipient (or extractor) extracts the message from the carrier image. The message can only be extracted if there is a shared secret between the sender and the recipient. The figure below shows the steganographic system. 
Our earliest records of steganography were recorded by the Greek historian Herodotus and date to Greek time.  When the Greek tyrant Histiaeus was held as a prisoner by king Darius in Susa  during the 5th century BC, he had to send a secret message to his son-in-law Aristagoras in Miletus. Histiaeus shaved the head of a slave and tattooed a message on his scalp.  When the slave’s hair had grown long enough he was dispatched to Miletus.
Another story from ancient Greece also comes to us via Herodotus.  The writing medium of the time was text, written on wax-covered tablets.  Demeratus, a Greek, needed to notify Sparta that Xerxes intended to invade Greece.  To avoid  capture, he scraped the wax off of the tablets and wrote the message on the underlying wood.  Then he covered the tablets with wax again.  The tablets appeared to be blank and unused so they passed inspection.
Invisible inks have always been a popular method of steganography.  Ancient Romans used to write between lines using invisible inks based on readily available substances such as fruit juices, urine and milk.  When heated, the invisible inks would darken, and become legible.  Invisible inks were used as recently as World War II.            
An early researcher in steganography and cryptography was Johannes Trithemius (1462-1526), a German monk.   His first work on steganography, Steganographia, described systems of magic and prophecy, but also contained a complex system of cryptography.  It was only published post humously, as Trithemius had feared the reaction of the authorities if it was published.  The earliest actual book on steganography was a four hundred page work written by Gaspari Schotti in 1665 and called Steganographica.  Although most of the ideas came from Trithemius, it was a start.  
Steganography in Text
Steganography in Images
  • Some Guidelines to Image Steganography
  • Least significant bit insertion:
Steganography in Audio
  • Digital Representation
  • Transmission medium
Processor                                Pentium 4
Primary Memory                    64/256/512 MB
Secondary Memory                40 GB
Floppy Disc                             3-1/2 inch
Monitor                                   Any monitor
Operating System                       Windows XP
Language                                 J2SE 1.5.0
Runtime Environment              JDK

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