Introduction About Steganography Computer Science Essay

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The purpose of the author to choose this topic is to make people realize about its presence and the usefulness of this technique and how much the risk if people used this to do criminality things.

Steganography is the term for tehnique to write hidden or secret messages, This term formed from combination of two Greek words which are Steganos and Graphein. Steganos means "hidden / protected" and Graphein means "writing" by combined these two meaning of the words, Steganography means protected writing or hidden writing. Main concept of Steganography is that the message to be sent is cannot be detected without using special technique. Even the people who are not aimed as the messages' recepient don't suspect that there are hidden messages on it.

2. History of Steganography

The first recorded time of using steganography was in 440Bc that two examples was mentioned by an ancient Greek historian " Herodotus" in the Histories of Herodotus.

Demaratus warned Greece about the upcoming attack by writing it directly on wooden wax tablet before applying beeswax surface. Wax tablets commonly used at that time of writing reusable surface, sometimes it used for abbreviations. Another example is an ancient Histiaeus, that mention another technique which shaved the head of someone and tattooing a hidden or secret message such as map on it. The grown hair would conceal the message, the aim of it is to lead to resistance to the Persians.

The first recorded use of term was in 1499 by Johannes Trithemius, he used the term "Steganography" as the title of his book which named as "Steganographia". A treatise on cryptography and steganography disguised as a book on magic. In general, the message will be appear as a something else: pictures, articles, shopping lists, or some other text and classic,

the message might be hidden between the lines of invisible ink in a personal letter.

3. Overview

3.1. The differences of Steganography and Cryptography

The differences between steganography and cryptography is in cryptography,

Once the message has been encrypted, people couldn't decode the message in to plain text without understanding the encryption algorithm / technique. In steganography, the message is very difficult to decode because most of the people couldn't detect the message, even they didn't know it there is a hidden message on it. Steganography and Cryptography can be combined and can use it together at the same time means it's already in the combined form. There are some computer programs to encrypt the message using cryptography technique and encrypt image into hidden image using steganography technique.

3.2. Advantage and Disadvantage of Steganography

The advantage of steganography over cryptography alone is that the hidden messages don't stand out and it can be passed in harmless content such as image. No matter how unbreakable of the message and will lead to the suspicions where the encryption is illegal. While cryptography protecting the hidden messages, steganography and cryptography are used together to ensure security of the covered message.

The disadvantage of steganography is hard to hide the long documents and there is a protection factor like the secrets are not protected by steganography and anything else. So if no one sees it, it can be safe otherwise it can be dangerous.

4. Digital Steganography Techniques

4.1. Least Significant Bit Steganography

Least Significant Bit or LSB is the simplest approach of hiding data within an image file or we can called it as Digital Steganography and there are many people used this technique, the hidden data that represented in binary form and overwrite it into LSB of each bytes. The amount of changes will be minimalized and indistinguishable to the human eye. It's much easier the hide the information into high resolution picture quality, GIF format and 8bit BMP files.

4.2. Chaffing and winnowing

Chaffing and winnowing is a digital cryptographic technique to sending data over channels that not secure without an encryption technique.

This technique name was derived from agriculture: the wheat that has been harvested and threshed is mixed with fibrous inedible husk. Husks and seeds are then separated by winnowing, and the chaff is discarded. This technique was developed by Ron Rivest. The steganography and encryption cannot be classified in either category.

This technique is terrific when compared to the common data encryption method because it allows the sender to deny the responsibilities of their encrypted messages. When using this technique, the sender can transmit the message in text form. Although both sender and receiver shared the secret key, they only used it for authentication.

However, third party may make special message and send it through confidential communications made ​​simultaneously by a third party and every special messages will be sent through the same channel.

4.3. Audio Steganography

The most common audio format to use in steganography is MP3 format and it's also the most common format that people use for their music files.

Therefore, there is also great for hiding information into a format that is more prominent, the more hidden data that might be easily forgotten. The technique that will be used in here is similar to the

The technique used is similar to the frequency of transformation discussed earlier. Basically the that to be hidden is store as in MP3 file format during the compression phase.

As in Layer 3 audio files compression process, the missing data selectively based on the user's bit rate has been determined. Hidden data is encoded in the parity bit of this information. The effective technique is we need to uncompressed the MP3 file and read the parity bit of the process. Because it leaves the mark on the distortion of music files.

4.4. Video Steganography

For video steganography, voice and image combination techniques can be used for it. Because the fact that the video is the combination of images/pictures and sound.

So Audio and Image steganography technique can be used to hide the data, because video file has a great size and the space to add a lot of data is more bigger and

So the technique can be applied in these two areas to hide data. Because the video file size, scope to add more data is much greater and therefore the possibilities of hidden data is detected are quite low.

5. Steganography Detection

Although many of the perfectly legitimate use of steganography, this can be misused by certain groups. Potential exists for terrorist groups to communicate using this technique to hide their messages and survive the rumor that Al Qaeda has been using it to communicate. Also of concern is that this technique can be used by pedophiles to hide the pornographic images in a seemingly harmless material.

Consequently the need to detect stenographic data has become an important issue for law enforcement agencies. Trying to detect the use of steganography is called steganalysis and can be either passive, where the existence of hidden data is detected, or active, in which an attempt is made to retrieve the hidden data.

Detection is similar to a watermark check. However, whereas before detection will be used when the mark is expected and may involve using the original files, in this case the original file is not available and there is no sign of that expected. Instead the file should be checked for the presence of hidden data in various formats. Because a large amount of hiding techniques, to detect all of them are feasible and indeed detect the presence of any kind can be time consuming.

6. Current Steganography Application (in which area (s) Steg play an important role.)

6.1. Data protection changes

Actually, the data embedded in programs most vulnerable steganography. However, this vulnerability will open a new direction towards a change in the information-protection systems such as Certificate "Digital Document Systems." This most recent example is that "no authentication required bureaus." If it is implemented, people can send "their digital certificate data" for every place in the world via the internet. No one can forge, alter, or modify the certificate data. If forged, altered, or destroyed, it can easily be detected by the extraction program.

6.2. Media Database systems

Hidden in the implementation of security in the region is not important, but a unified two types of data is the most important. Data media (pictures photos, movies, music, etc.), some associated with other information. Photo images, for example, may follow.

(A) Title of the picture and some kind of information

(B) the date and time of photograph

(C) camera and photographer information

Previously, it was a note next to each picture in the album. Recently, used in almost all digital cameras. They are cheap, easy to use, and quick to shoot. They finally make people feel reluctant to work on annotating each picture. Now, most houses are stuck with large amounts of PC file photo. In this situation it is very difficult to find a specific shot in a pile of pictures. An album software "images" may help a little. You can sort the pictures and make a few word descriptions for each photo. If you want to find a particular image, you can create keywords to search the target image. However, the explanation of the data in the software is not united with the target image. Each description has a link to pictures only. Therefore, if you transfer the software image into different albums, all explanations of missing data

This problem is technically referred to as metadata (eg, explanation of the data) in the media database system (photo album software) are separated from the media data (image data) in a database management system (DBMS). Steganography can solve this problem because steganography program brings together the two types of data into a single operation by embedding. Thus, metadata can easily be transferred from one system to another without restriction. Specifically, you can embed all your good / bad memories (of you look around trip) at each snap shot from a digital photograph. You can send embedded pictures to your friends to take your memory on / her PC or you can remain silent on your own PC to enjoy the memory of ten years after the excavation.

6.3. Confidential communications and store confidential data

Secure communication and storage of confidential data in the embedded data security is very important in this regard. Historically, steganography has been exposed in this regard. Steganography provided to us:

(A) Potential to hide the existence of secret data

(B) Violence to detect the (hidden, embedded) data

(C) Strengthening the confidentiality of data encrypted

In practice, when you use a particular steganography, you must first select the data match the size of ships embedding data. Ships must not dangerous. Then, you put your confidential data using the embedding program (which is one component of steganography software) together with several keys. When extracting, you (or your party) using the dig program (other components) to recover data embedded with the same key ("key the same" in terms of cryptographic). In this case you need the negotiation "key" before you start the communication.

Stego attach a file to an e-mail message is a simple example application in this area. But you and your party must do "shipping-and-take" action can be taken by third parties. So, e-mail is not a method of communication is strictly confidential.

There is a simple method that does not have-key negotiation. We have a model Anonymous Covert Mailing System."

There are several other methods of communication that uses the Internet Webpage. In this method, you do not need to send anything to your party, and no one can detect your communication.

6.4. Access control systems for digital content distribution

Today, digital content is getting more and more generally distributed by the Internet than ever before. For example, the music company releases new album on their webpage for free or charge. However, in this case, all the contents evenly distributed to people who access the page. So, regular web distribution scheme is not suitable for a "case-by-case" and "selective" distribution. Of course, this is always possible to attach digital content to the e-mail and send messages to subscribers. But it will take a lot of time and labor costs.

If you have some valuable content, you think its okay to provide others if they really need it, and if possible to upload content like on the Web in some ways a secret. And if you can remove the key "special access" to take selective content, you'll be very happy about it. Stenographic scheme may help to create such a system.

7. The Usage of Combined Cryptography-Steganography

From description above, we all already know that steganography is not the same as cryptography. So, when these 2 methods are combined, it will result very powerful encryption method. Since data hiding techniques have been widely used to transmission of hiding secret message for long time. Ensuring the data security is a huge challenge for all computer users that want to secure their data from others. By combining these methods, the data encryption that can be done by a software and then embed the cipher text in an image or any other media with the help of stegano key. The combination of these two methods will tweak the security's robustness of the data embedded.

8. Summary

Steganography has been made ​​use of hidden data is interesting and effective way. This method can be used to reveal the devious tactics and the first step is used to recognize the existence of these methods.

There are many good reasons to use such this method to hide the data including watermarks or more secure way of storage center such as passwords or Core processes.

In any case, the technology is easy to use and difficult to detect. The more you understand the features and functions, the more ahead you will be in the game

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