07-06-2012, 12:32 PM
Image Steganography Schemes For Image Authentication And Verification
Steganography_in_Images.ppt (Size: 1.25 MB / Downloads: 76)
STEGANOGRAPHY DEFINED
The word steganography is derived from the Greek words “stegos” meaning “cover” and “grafia” meaning “writing” defining it as “covered writing.
There exist two types of materials in steganography: message and carrier. Message is the secret data that should be hidden and carrier is the material that takes the message in it.
TEXT STEGANOGRAPHY
Text steganography can be achieved by altering the text formatting, or by altering certain characteristics of textual elements.
These criteria, reliable decoding and minimum visible change, are somewhat conflicting; herein lies the challenge in designing document marking techniques.
The three coding techniques proposed to illustrate different approaches are:
Line-shift coding
Word-shift coding
Feature coding
IMAGE STEGANOGRAPHY
To hide information, straight message insertion may encode every bit of information in the image or selectively embed the message in “noisy” areas that draw less attention—those areas where there is a great deal of natural colour variation.
The message may also be scattered randomly throughout the image. A number of ways exist to hide information in digital media.
LSB INSERTION
Least significant bit (LSB) insertion is a common and
simple approach to embed information in an image file.
In this method the LSB of a byte is replaced with an M’s bit.
This technique works well for image, audio and video steganography.
To the human eye, the resulting image will look identical to the cover object.
