Information hiding

As the name suggests, Information Hiding is an art of hiding data and communication inside other data and communication. Information hiding is somewhat similar to cryptography. On the other hand it seems to be stronger than it. Cryptography hides content of communication; information hiding hides even the presence of communication. Information hiding means communication of information by hiding in and retrieving from any digital media. The digital media can be an image, an audio, a video or simply a plain text file. Information hiding contain four sub-disciplines

a) Covert Channelsb) Steganographyc) Anonymityd) Copyright marking

a) Steganography: - Steganography means, literally, covered writing. Steganography is the art and science of hiding information such that its presence cannot be detected. Steganography is the hiding of secret message within an ordinary message and its extraction at destination point. The main goal of steganography is to communicate securely in a completely undetectable manner. Steganography techniques may be roughly classified into linguistic steganography and technical steganography.

b) Watermarking: - Watermarking is a branch of information hiding which is used to hide additional information in digital media like image, audio, video, or text. A digital watermark is defined as a visible or invisible identification code that is permanently embedded in the data, to transmit hidden data. It remains present in the data even after the decryption process. It usually provides copyright protection of intellectual property. The watermark is later used to identify the de facto copyright owner of the object.c) Anonymity: - Anonymity is finding ways to hide the meta content of messages, i.e., the sender and the recipients of a message. There are different varieties depending on who is anonimyzed: the sender, the receiver or both. Web applications have focused on receiver anonymity whereas email users are concerned with sender anonymity.

d) Covert channels: - it is defined as the communication paths that were neither designed nor intended to transfer information at all. These channels are typically used by untrustworthy programs to leak information to their owner while performing a service for another program.

Application of Information Hiding: -

Information hiding is an area of great interest due to its applications in copyright protection of images, data, passport control, CDs, DVDs, videos and so on.