steganography and example
Steganography
Steganography is the art and science of writing hidden messages, or hide in a way that besides the sender and the recipient, no one knows or realizes that there is a secret message. In contrast, cryptography disguise the meaning of a message, but does not conceal that there is a message. The word steganography (steganography) is derived from the Greek Steganos, which means "hidden or disguised," and graphein, "write".
Now, the term steganography includes the concealment of digital data in computer files. For example, the sender begins with regular image file, then set the color of each pixel to the-100 to adjust a letter in the alphabet (the change is so subtle that no one knew if he did not really notice).
In general, steganographic message appears with other way, such as pictures, articles, shopping lists, or other messages. The message of this writing is the writing that surrounds or covers. For example, a message can be hidden by using invisible ink between the visible lines.
Steganographic technique involves a lot of communication methods to hide secret messages (text or images) in the other files that contain text, images, audio even without showing the characteristics of tangible or visible changes in the quality and structure of the original file. These methods include invisible ink, microdots, arrangement of words, digital signatures, hidden paths and wide spectrum of communication. The purpose of steganography is to hide or conceal the existence of a hidden message or an information. In practice most thinly settled by making changes to other digital data whose content would not attract attention from potential attackers, as an example of an image that looks harmless. These changes depend on the key (the same in cryptography) and the message to be hidden. The person receiving the images can then be concluded undisclosed information by replacing the correct key into the algorithm used.
In this way steganographic method is very useful if used in a way because a lot of computer steganography digital file format that can be used as media to hide the message. Format commonly used include:
Image formats: bitmap (bmp), GIF, PCX, jpeg, etc..
* Audio formats: wav, voc, mp3, etc..
* Other formats: text files, html, pdf, etc..
Excess steganography than cryptography is his message did not attract anyone's attention. Coded messages in cryptography that is not hidden, though not solved, will lead to suspicions. Often, steganography and cryptography are used simultaneously to ensure the security of the secret message.
A steganographic message (plaintext), usually is first encrypted by some traditional sense, which produces ciphertext. Then, covertext modified in some way that contains the ciphertext, which produces stegotext. For example, the size of font, size spacing, typeface, or other covertext characteristics can be manipulated to carry a hidden message, only the recipient (who must know the technique used) can open the message and decrypt it.
* 1 Steganography Method
o 1.1 Least Significant Bit Insertion (LSB)
o Algorithms and Transformation 1.2
o 1.3 Redundant Encoding Pattern
o 1.4 Spread Spectrum method
* 2 steganalysis and Stegosystem
Most steganography algorithms using a combination of field types of techniques to perform a task in cloaking a secret message in an envelope file. A steganography program needed to do the following things (whether implicit or explicit through an estimated via a calculation), find the excess bits in a veil of files that can be used to cloak a secret message in it, select some of them for use in data envelop and cloaking the data in pre-selected bits. There are four types of Steganography methods, namely:
Insertion Least Significant Bit (LSB)
The method used to hide messages in digital media is different. For example in the image file messages can be hidden by using a low bit or paste it on the rightmost bit (LSB) of pixel data composing the file. As we know for 24-bit bitmap file, each pixel (dot) in the image containing an array of three colors red, green and blue (RGB), each prepared by a number of 8 bits (bytes) from 0 to 255 or the binary format 00000000 through 11111111. Thus, at each pixel 24-bit bitmap file you can insert the 3 bits of data. Deficiency of LSB Invertion: Can be concluded from the example of 8 bit pixel, using LSB Insertion can drastically change the constituent colors of the pixels. This can be significantly different from the cover image into a stego image, so it was showing signs of steganography. Color variation is less clear with 24-bit image, however the file is very large. Between 8 bit and 24 bit image processing vulnerability in the image, such as cropping (failure) and compression (compression). The advantage of the LSB Insertion: The greatest advantage of the LSB algorithm is fast and easy. And also the algorithm has a steganography software that supports the work of the principal elements of the LSB color palette manipulation (painting).
Algorithms and Transformation
Compression algorithm is a method of steganography to hide data in mathematical functions. Two of these functions is the Discrete Cosine Transformation (DCT) and Wavelet Transformation. DCT and Wavelet function is to transform data from one place (domain) to a (domain) to another. DCT function is to transform data from a spatial (spatial domain) to the frequency (frequency domain).
Redundant Pattern Encoding
is drawing a small message on most images. The advantage of this method is that it can survive the cropping (failure), the loss is not to draw larger messages.
Spread Spectrum method
Spread Spectrum Steganography scattered as an encrypted message (encrypted) through the picture (unlike in the LSB). To read a message, the recipient requires the crypto-key algorithm and stego-key. This method is also still vulnerable to the destruction or damage from the compression and the image (picture).
Steganalysis and Stegosystem
Such as cryptography and cryptanalysis, steganalysis is defined as an art and science of detecting hidden information. For the purpose of steganography is to conceal the existence of a secret message, a successful attack on a steganographic system consists of detecting that a file that is believed to contain hidden data. As in cryptanalysis is assumed that the steganographic system has been known by the attacker and therefore the security of steganographic system depends only on the fact that the secret key is unknown by the attacker.
Stegosystem here contains about attacks-attacks carried out against a system of steganography, an important distinction must be made between the attack-passive attack where the attacker can simply cut and attack-attack data on which the attacker can also manipulate the data. In the figure below shows a diagram to explain the stego system. The circles indicate the places that potential attackers have access to one or more of these places due to attack-attack different types, and also serves to perform an active attack. If the circle is not filled, the attacker can only perform a passive attack that is blocking the data cut.
Attack-attack following the model of stegosistem enable this:
* Only-Stego-Attack (Attack only Stego). Attackers have prevented the stego data and to analyze it.
* Stego-Attack (Attack Stego). The sender has used repeatedly to cover the same hidden data. Attackers have stego files that come from the cover of the same file. In each of these stego files, a different message is hidden.
* Cover-Stego-Attack (Attack sheath Stego). Attackers have prevented the stego file and know the cover of which files are used to produce this stego file. This provides an advantage over the stego-only attack to the attacker.
* Manipulating the stego data (stego data Manipulate). The attacker has the ability to manipulate the stego data. If the attacker only wants to determine a hidden message in this stego file, usually it does not provide a profit but have the ability to manipulate data in stego which means that the attacker was able to move a secret message in the stego data (if any).
* Manipulating the cover data (Manipulate data disguised). Attackers can manipulate the data hidden and hinder the stego data. This can make the task of determining whether the stego data contains a secret message is easier for the attacker.
example:
Steganography - hiding messages
Quantcast
Steganography is a way to write a hidden message. Hidden message is inserted in a text.
Text created in such a way that other people who read are not aware of the existence of these hidden messages.
steganography examples:
Paras face
beauty, kindness
lively and laugh your laughter
rankle
only you ...
Your name is etched in my mind
Yoko,
Is there still a place in your heart?
This heart pain Yoko
pain pierced my soul
But remember,
always my love for you
Do not you ever forget
my love,
There is only you, Yoko ...
Anyone know the contents of the message hidden in these love poems?
Steganografinya rules are:
For each stanza contains one word. Ignore punctuation such as periods and question marks.
To take the first letters of each verse in the first row, the last letter on the next line, then for
The next line again take the first letter and last letter to the next line. So, the formula for each
baitnya is the early-late-late-early (looping).
Now that would have been able to read hidden messages. What is it?
yup, the message is: SELECT NUMBER SEVEN. (The answer I gave a blue color)
There are many ways to make steganography. Able to take the first letter of each word in a sentence, or
the last letter of each word in a sentence. Or a more complicated way is by using the image
and sound.
Another way is to write hidden messages using cryptography. The difference, cryptography change the overall message into numbers or letters that have been converted according to the formula that made. So the message really benartidak can be read by others because it could not read the sentence,
Steganography: 4. Example Application
Content
For those who have not understood what exactly that steganography can be seen in my previous article http://andreastjong.wordpress.com/2008/09/18/steganografi-1pendahuluan/.
Before we begin this example there are several things that must be prepared beforehand. First of all is a steganography software (used Hide4PGP aka H4PGP20W), you can download at http://www.heinz-repp.onlinehome.de/H4PGP20W.ZIP. Relax because this software is free. Then the data must also be prepared to hide and the media to be used, in this example I use a gif image file format (test.gif) with dimensions of 200 × 230, size 111kb, while for the media to be inserted I will use an audio file formats dengn wav (stego.wav)
Steps you must do to menyisisipkan data:
1. Download H4PGP20W.zip
2. extract in one folder (eg C:)
3. Place the file you want inserted and the media to be inserted into that directory (stego.wav and test.gif)
4. open a command prompt
5. Go to the directory where you'd mengekstrakt H4PGP20W
6. Type the following command "Hide4PGP stego.wav test.gif"
7. Congratulations because you've managed to stego.wav melanyisipkan test.gif files (you can download the file delete test.gif if you want)
Steps you must do to extract data
:
1. open a command prompt
2. Go to the directory where you'd mengekstrakt H4PGP20W
3. Type the following command "Hide4PGP-x stego.wav test.gif"
4. Please check in that directory, is there a file called test.gif
Creating a simple steganographic application with vb.net - With source code
Preliminary
Our goal is to build a simple application that can send and receive encrypted messages embedded in Rich Text Format: *. DOC, *. RTF, EMAIL / MessageBody /, etc. The user has the ability to choose a fake text he wanted and the program should be able to say whether or not this fake text will be in accordance with the original text.
Users can set a different password for each message sent. This will enable managers to send two groups of two different messages with two different passwords by using the same false text. Thus, you will be able to send messages encrypted and hidden in the source code wherever you choose! Just look at the EXE to see for themselves.
How does it work?
We're not going to change the text itself, but we will change the attributes of the text invisible. These attributes are many and impossible for the web server to keep track of them all. There are many methods and tracking Steganographic they will waste a large amount of processing for an uncertain outcome. Be aware that steganography is more effective than encryption when used in a way that benar.Penghapusan all attributes is not an option, so we will choose the size and color. This figure would underscore my point:
Mode size changes
In this mode, we will change the size of the characters in the fake text according to selected font size and differential factors. We will use 2 sizes, X1 and X2. X1 is selected font size and X2 is selected font size coupled with differential factor. Bit 0 is represented by the characters that the size of X1. Bit 1 is represented by the characters that the size of X2.
Look! Not all support each font size you select, so the program will suggest you to decrypt your messages before you send it to ensure that the fonts that support you (X2) size. The recipient must have the same font you used installed in the machine. This may not be a problem for you because there are a variety of font families in common between the Windows OS versions. Recipients must also know who selected the font size you use for decryption. After we hide the real message in a false message, the remaining characters will be sized fake messages such as X1.
Color change mode
This is the preferred mode to use, because it is very stable and safe. In this mode, we will change the color of characters in the fake text selected in accordance with the color and color programs are calculated. We will use 2 colors, X1 and X2. X1 and X2 selected color is the color of the program is calculated. The program will seek to find the closest color that is impossible to recognize the difference with the naked eye. Bit 0 is represented by the characters whose color X1. Bit 1 is represented by the characters whose color X2. The recipient must know which color you have chosen for decryption. After we hide the real message in the message false, false messages remaining characters will be colored like the X1.
When do we stop?
We will not use certain characters from the plain text alphabet. That is, when we will get a certain character, we will stop the generation of output messages. In this way we prohibit users from using the character, so do not underestimate any characters input. Here is an example.
Examples
Imagine using the "/" as the 'End Of Message' sign, but some users may want to send a message like this:
/ \ \ \ / \ \ \ \ / \ / \ \ \ \ \ \ / \ /
"Now," you ask, "What is this?" This is a message encrypted with (/, \) stands for the bits (0,1). So, this is the bit stream is encrypted. If you decrypt it, you'll have a bit. Then if you change it to bytes, they can be anything: photos, text, word documents, sound, etc. Here, we encrypted steganographic decrypted some text - in a fake message that looks - to have a steganographic encrypted text, that is not visible / \ / \ / / ... This is a steganography doubled. We can add a new layer of steganography when the output byte is a Word or RTF file. To a large Word or RTF file, this is more than likely due to storage size divided by 8. It's not too bad, as a plain text book with 800 pages can have the required size.
As you may have noticed, we need to store additional information for the size. We will use 4 bytes to store size. This means 4 * 8 bits or 32 bits, ie the first 32 characters in the text false. We will take any 2 digit number and store it in a size 1 byte. Here you can see that the first 32 characters in the fake text is very important, even if they do not look like a space character.
How to use it?
There Paste and Delete button for each text box, in addition to Import and Export buttons to output text box. First, copy the text of any useless and use the Paste button near the text box to paste a fake. Write the real message in the text box real message. This program will tell you about bogus text necessary capacity. Do not use small text big fake real message, as this will increase processing time.
Try to cut text from a false message to have the optimum capacity, ie the smallest capacity that is greater than the required capacity. This is shown in the upper text box nyata.Selanjutnya messages, select the mode you enter the password you want. If you use size mode, verifying that the difference in font size for the output message is not visible. If not, change the font size and try again until you see that the difference is not visible. You can use the space bar trick also, as mentioned later. Then export the output messages to a RTF file using the Export button. That's it! Now you can attach it to your email and send it anywhere.
Using the code
I have outlined the main procedures that will unhide the text in the text. Code comments for each step.