Stenography

Stenography



Introduction

Although the use steganography began many centuries ago, this field recently became an important area of interest for individuals, corporations, and governments because of technology. People are constantly transferring important information online due to the increased connection caused by computers and the Internet. This concept is the backbone of steganography today. Steganography is the art of hiding information in a cover document or file. Therefore, today, steganography is usually accomplished by electronic encryption, which is the encoding of information that can only be decoded by the person possessing the correct electronic key. A cover document contains this hidden encoded information, and usually the transfer of this secret information is very secure. This paper will explain the technical processes behind steganography as well as emphasize the benefits and drawbacks of using this technology through the viewpoints of different interest groups.

The Task Of Hiding Information

Steganography now is accomplished in the digital world using mathematical algorithms to encrypt data. First, one scrambles the information using an algorithm. This algorithm creates a key later used to transform the encrypted data back to its original form so that the receiver can understand it. For example, we could use the multiplication of two 50-digit prime numbers to create a 100-digid product, which becomes the key (Daniel). There are public and private keys. Private key cryptography uses the same key for both the encryption and decryption process. Therefore, the sender and receiver of the secret information have the same key. Public key cryptology uses both a public and private key. The sender uses the public key, which may be published in directories. The private key is necessary for the receiver to decrypt the message (Petitcolas).

One may hide information in a variety of files. Steganography replaces unused parts of data with the secret information. It is possible to hide information in text, for example, in the spaces between words. This type of information hiding is more successful than steganography that consists of hidden information in infrequent spelling errors and in words replaced by synonyms. One of the main requirements for hiding information in digital sounds and images is redundant, repetitive information. Steganography uses this part of the sound or image to hide the secret information. One unique example of hiding information is the embedding of a mobile telephone conversation into an Integrated Services Digital Network (ISDN) video conferencing system. It is possible to do so without seriously changing the quality of the video, and with the correct key, one could decode the conversation (Petitcolas).

The easiest way to hide information is to replace the least significant bit (LSB) of every element with one bit of the secret message. For example, when a picture is the desired cover document, each pixel of the picture contains 24 bits of information, which, to the computer, consists of 0s and 1s. To insert the secret information, one can change these 0s and 1s to bits of secret information (Castelluccio). The most useful way to insert these bits is do to do so in ...