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Steganography is a technique used to hide the message in vessel data by embedding it. The Vessel Data which is visible is known as external information and the data which is embedded is called as internal information. The external information is not much useful to the data owner.
The techniques used in Steganography makes hard to detect hidden message within an image file. By this technique we are not only sending a message but also we are hiding the message. Steganography system is designed to encode and decode a secret file embedded in image file with a random Least Significant Bit(LSB) insertion technique. By using this technique the secret data are spread out among the image data in a random manner with the help of a secret key. The key generates pseudorandom numbers and identifies where and in which order hidden message is laid out. The advantage of using this method is that it includes cryptography. In cryptography, diffusion is applied to secret message.
The information communicated comes in number of forms and is used in various number of applications. In large number of these applications, it is desired that the communication has to be done in secrete. Such secret communication ranges from the obvious cases of bank transfers, corporate communications, and credit card purchases,and large percentage of everyday e-mail. Steganography is an ancient art of embedding a message in such a way that no one,except the sender and the recipient,suspects the existence of the message. Most of the newer applications use Steganography as a watermark, to protect a copy right on information. The forms of Steganography vary, but unsurprisingly, innocuous spam messages are turning up more often containing embedded text. A new transform domain technique for embedding the secret information in the integer wavelet which is transformed on a cover image is implemented here.
A technique which is used to scramble a secrete or a confidential message in order to make it unreadable for a third party is known as the Cryptography.Now-a-days its commonly used in the internet communications.cryptography can hide the content of the message but it cant hide the location of the secrete message.This is how the attackers can target even an encrypted message.Water marking is the another information of hiding the digital data or a picture or musical sound.The main purpose of this watermarkinginformation is to protect the copyright or the ownership of the data.In this technique the robustness of the embedded evidence,that can be very small, is the most important.The external information which is visible is the valuable information in the watermarking technique.
steganography is a technique which is used to make the confidential information imperceptible to the human eyes by embedding the message in some dummy data such as the digital image or a speech sound.There is a research topic about the steganography known as the steganalysis.The main objective of this steganalysis is to find out the stego file among the given files.It is a technique which is used to detect the suspicious image or sound file which is embedded with the crime related information.So,we need to make a "sniffer-dog-program" to break the steganography.However,it is too difficult to make a program that really works.
All the traditional steganography techniques have very limited information-hiding capacity.They can hide only 10% (or less) of the data amounts of the vessel.This is because the principle of those techniques which were either to replace a special part of the frequency components of the vessel image, or to replace all the least significant bits which are present in a multivalued image with the secrete information.In the new steganography which we are using uses an image as the vesel data, and we need to embed the secrete information in to the bit planes of the vessel.The percentage of information hiding capacity of a true color image is around 50.All the "noise-like" regions in the bit planes of the vessel image can be replaced with the secret data without deteriorating the quality of the image,which is known as "BPCS-Steganography", which stands for Bit-Plane Complexity Segmentation Steganography.
The word Steganography is of Greek origin and means “covered, or hidden writing”. Its ancient origins can be traced back to 440BC.
Steganography is a technique which is used now a days to make confidential information imperceptible to the human eyes by embedding it in to some innocent looking "vessel" data or a "dummy" data such as a digital image or a speech sound.In a multi bit data structure a typical vessel is defined as a color image having Red,Green and blue components in it.By using a special extracting program and a key the embedded information can be extracted,the technique of steganography is totally different from "file deception" or "file camouflage" techniques.
A technique to hide the secrete data in a computer file which almost looks like a steganography is known as a "file deception" or "file camouflage".But actually, it is defined as a trick which is used to disguise a secret-data-added file as a normal file.This can be done as most of the computer file formats have some "don't-care portion" in one file.For instance if we take some file formats as jpeg,mpeg3 or some word file these looks like the original image,sound or document respectively on the computer.Some of them could have misunderstood that such a trick is a type of Steganography.However,such files can have an extra lengthy file sizes, and they can be easily detected by most of the computer engineers.So, by this we can understand that the file deception is totally different from that of the steganographic techinque which we are discussing here.
Many of the "Steganography software" which is in the market today is based on the file decepetion.If we find a steganography program that increases the output file size just by the amount we have embedded, then the program is obviously a file deception.If there is some secrete data then we should encrypt in such a way that it is not readable for the third party.A solution to Keep secrete information very safe is known as Data Encryption.It is totally based on scrambling the data by using some type of the secrete key.
However,encrypting the data will draw more attention of the people who have not encrypted the data.So, it is very to the owner to know whether the data is encrypted or not.By, this we can know that the encrypting is not enough. There is another solution which is known steganography.
There are two types of data in steganography, one is the secret data that is very valuable and the other is a type of media data "vessel" or "carrier" or "dummy" data.Vessel data is essential, but it is not so valuable.It is defined as the data in which the valuable data is "embedded". The data which is already embedded in the vessel data is called "stego data".By using the stego data we can extract the secret or the valuable data. For embedding and extracting the data we need a special program and a key.
A typical vessel is an image data with Red, Green, and Blue color components present in it in a 24 bits pixel structure. The illustration below shows a general scheme of Steganography.
Steganography is a technique which is used to hide secret data by embedding it in some innocent looking media data like Mona lisa in the above picture.The data which is embedded is very safe because Steganography hides both the content and the location of the secret information.In the media data there are many different methods to embed the data.It is highly impossible to detect which method is used for embedding the data.Steganography can co-operate with cryptography in the sense that it can embed the encrypted secret data and make it much safer.
The most important point in the steganography technique is that the stego data does not have any evidence that some extra data is embedded there.In other way, the vessel data and the stego data must be very similar.The user of the steganography should discard the original vessel data after embedding,so that no one can compare the stego and the original data.
It is also important that the capacity for embedding the data is large.As it is larger it is better.Of all the currently available steganography methods the BPCS method is the best.