19-02-2013, 11:39 AM
STEGANOGRAPHY - The art of hidden information
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ABSTRACT:
Ever since the problem of spying come into existence, there has always exists the necessity of sending confidential messages between two organizations.
STEGANOGRAPHY deals with sending secret message by embedding them into another message. Now, it is gaining new popularity with the current industry demands for digital watermarking and fingerprinting of audio and video.
To human eyes, data usually contains known forms like images, e-mail, sounds and text. Most Internet data naturally includes gratuitous headers, too.
Take a moment to read the previous paragraph. If you think it is a vague and awkward, then we have succeeded in using a very simple form of steganography. By taking the first letter of the every word of the previous paragraph we will discover a message that says: The duck flies at mid-night. In this paper, we aim to present a general introduction to steganography, or
Data-hiding, as it is sometimes just known. We then turn to data-hiding in four different media: that of text, images, audio and video signals. Each offers different challenges, and solutions to those challenges. This paper aims to outline a general introduction to steganography - what it is, and where it comes from and various data hiding techniques.
The following concept of stenography is under our project and is practically implemented by us.
INTRODUCTION:
Steganography, from the Greek, means covered or secret writing, and is a long-practiced form of hiding information. The image, or watermark, that would appear on bank notes when they were held up to the light is an example of steganography, the art of secret writing. For example, that picture of your cat could conceal the plans for your company's latest technical innovation.
''“The goal of steganography is to hide messages inside other harmless messages in a way that does not allow any enemy to even detect that there is a second secret message present.
Steganography
The method of hiding one piece of information within another is called Steganography. The meaning of this Greek term is 'covered writing'.
Masking and Filtering
They hide info in a way similar to watermarks on actual paper and are sometimes used as digital watermarks. Masking images entails changing the luminance of the masked area. The smaller the luminance change, the less of a chance that it can be detected. Stego-images that are masked will keep a higher fidelity than LSB through compression, cropping and some image processing. The reason that a stego image encoded with masking degrades less under JPEG compression is that the secret message is hiding in the significant areas of the picture.
Redundant Pattern Encoding
Patchwork and other similar tools do redundant pattern encoding, which is a sort of spread spectrum technique. It works by scattering the message throughout the picture. This makes the image more resistant to cropping and rotation. Smaller secret images work better to increase the redundancy embedded in the cover image, and thus make it easier to recover if the stego-image is manipulated.
Encrypt and Scatter
The encrypt and scatter technique tries to emulate white noise. White Noise Storm is one such program that employs spread spectrum and frequency hopping. It does this by scattering the message throughout an image on eight channels within a random number that is generated by the previous window size and data channel. The channels then swap rotate, and interlace amongst each other. Each channel represents one bit and as a result there are many unaffected bits in each channel. This technique is a lot harder to extract a message out of than an LSB scheme because to decode you must first detect that a hidden image exists and extract the bit pattern from the file
Detection
Even though stego-images can rarely be spotted by the naked eye, they usually leave behind some type of fingerprint or statistical hint that they have been modified. It is those discrepancies which an analysis tool may be able to detect. The simplest technique is to measure the entropy of redundant data and check if its statistical properties have deviated from the data collected from the original image.
CONCLUSION:
We are at a point in the learning curve in the evolution of this technology where steganography is poised to take off in a really big way. With more and more users logging into the World Wide Web and data being exchanged in a huge proportion the validity and security of this data becomes a very important issue. Though it is not realized a huge chunk of the world economy can be subverted using interception of messages. In this paper we are not dealing with such heavyweight issues I intend to form a basic platform for further research into the matter. It is through a number of these small techniques only that we can finally build the powerful algorithms to avoid disasters like the 9/11 where concealed data played a crucial role. Steganography is here to stay