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ADAPTATION OF TEXT STEGANOGRAPHIC ALGORITHMS FOR HTML

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ADAPTATION OF TEXT STEGANOGRAPHIC ALGORITHMS FOR HTML Powered By Docstoc
					ADAPTATION OF TEXT STEGANOGRAPHIC ALGORITHMS FOR HTML
Stanislav Sergeevich Baril’nik Igor Vladilenovich Minin Oleg Vladilenovich Minin
Nowadays the Internet is a highly developed communication system. Every day the number of the users of the Internet increases for thousands of people. This system is open for everybody: either a law-abiding and decent person or a quite opposite one. This leads to such problems of the defense of information as copyright and transmission of hidden messages via World Wide Web through open communication channels. This article covers methods, which can help to solve these problems with usage of text steganographic algorithms. Usually, been based on peculiarities of HTMLlanguage, the information of authorship is indicated on an appropriate page in three main ways:  directly in the text, usually at the foot of the page;  in the form of the commentaries in the document;  via tag <Meta>. But all these indications of authorship can be easily modified and afterwards it is rather problematic to prove the copyright for this or that document. Apart from lawful ways it is expedient to use information ways of defense. Algorithmic mechanisms (mainly, steganographic and cryptographic), little by little, will allow to secure access to and transmission of works and supplement lawful protection provided by law and/or contract effective technological defense. They are aimed at resisting threats with the help of technique itself. This phase was well depicted by Charles Clark in his famous phrase, “The answer for the machine is contained in the machine” – it means that critical situation with offense against the rights of authors and publishers in the internet can be solved only with the help of new communication systems. Use of special stealthographic technologies which enable placing within web-document (HTML-

codes) “invisible” for unauthorized person messages will help to solve this problem at least partly. [3] Most of well-known today programs like Steganos for Windows help to hide information in different types of files. Let’s have a look at principle of work of such a program on a model of text file. Bits of hidden information are introduced in a form of unprintable symbols. Such symbols are a “gap” and a “horizontal tabulation”. Thus, we can present bits in the form of symbols: “1” – “gap”, “0” – “horizontal tabulation”. Each byte of hidden information is transformed into a succession of these symbols where each symbol corresponds with a bit of hidden byte. For example: Hidden byte – 0х43 = 0100 0011 => « || | | | | | |», where | | is «Gap», | | is «Horizontal tabulation». Then this succession is placed at the end of the line and becomes “invisible”. In this way you can hide one byte of information in a line but it is easily detected. For this it is enough to mark the text or make the text-editor mark unprintable signs (¶). Most of programs which enable to hide information in the text work on the same principle. In picture 1 one can see the result of the work of program Steganos for windows. Text-editor in the mode of representation of unprintable symbols (¶ – switching this mode in Microsoft word). « · » is a “gap”, «→» is “horizontal tabulation”, « ¶ » is a line-shift. Thus, editor shows “visibility” of hidden information.

Picture 1. The result of the work of the program Steganos for Windows

Analysis of the algorithm of “Steganos for Windows”-program work allows to improve some of its characteristics. Let HTML-file be a container. For increasing concealment of information we will insert received succession not at the end of each line, but only at the end of lines which end with a tag (<html>, </titled>, </body>, <br>, <td> and so on). This permits not to represent hidden gaps and horizontal tabulations on the page. Below, in picture 2, one can see the result of such an algorithm in the same text editor in the

mode of representing unprintable signs. In the picture one can see that hidden information is represented only after tags.

Picture 4. The result of the work of the algorithm in Hex (16th) editor.

Picture 2. The result of improved algorithm.

You can use this peculiarity for author’s notes or numerical watermarks in protection against copying [3]. Such an algorithm (in described below program) is named Mode 1. Besides, the program allows disclosing hidden bytes on this algorithm and putting them into a separate file. However, one should see a page in a form of a text-file with markers of line-shifts. Here one can find hidden information and delete it. To remove this defect we offer the following algorithm of work. Let’s make use of the peculiarity of line-shift. In Windows for line-shift two symbols are used: 0x0D, 0x0A. In modern UNIX operational systems one symbol is enough for that: 0x0A. Most of texteditors can understand and correctly represent both formats of line-shift. Using this peculiarity one can hide bits of hidden information. «0»- 0x0A, «1»0x0D 0x0A, i.e. presence of 0x0D is «1». Thus, in every line of a text one can hide one bit and can disclose it only when looking through file in Hex (16th) form, moreover, one can not always disclose it because the presence or absence of 0x0D symbol doesn’t provoke any suspicion, especially, such as unnecessary gaps and horizontal tabulators at the end of the line. In pictures 3 and 4 there is shown the result of such an algorithm in text and hex editors.

While working with html-file one can hide a bit not at the end of the line, but only after tags. So, if one uses this mode for authorship protection it will be more difficult to find and remove hidden bits than when working with the previous algorithm (unprintable symbols at the end of lines with tags). This algorithm can be used for secretive transmission of information. If a criminal knows that information is transmitted and guesses that it is hidden in such a way (0x0D at the end of the line, as at the end of different lines there will be different endings), then, with the aim of masking hidden bit of information of their visual analysis in Hex-editor, one can put down at the end of each line of the text different endings (by casual), and read only necessary endings (in this case, only lines ending with a tag). So, it will be difficult to read such bits if you don’t know the mask. In pictures 5 and 6 there is shown the difference between files with casual endings of lines and with fixed notes (0x0D, 0x0A).

Picture 5. File-result with putting down different endings by casual

Picture 3. The result of the work of the algorithm in text editor. Picture 6. file –result without putting down different endings by casual.

Besides, the program allows disclosing hidden bytes on this algorithm and putting them into a separate file. Such an algorithm in the program covered below is called Mode 2. Comparative analysis of modes of operation Each mode has its advantages and disadvantages. The first mode and Program Steganos for Windows possesses less degree of concealing than the second one, because it is much easier to detect gaps and horizontal tabulations at the end of the line than different line-shifts (переходы строк). So, the information hidden by algorithm of the second mode is more protected from disclosing. However, as for the number of hidden information then the second mode is worse. For example, to hide the line, “Author: Barilnik Stanislav (c) Novosibirsk March 2007 Program Steganography. All the rights are reserved” which contains 105 symbols; it will require 105 lines in the first mode. In program Steganos for Windows this meaning will take about 20 lines more, as this supplement hides only files and doesn’t work with separate lines. So, at first the hidden line has to be saved into a file and only after this it can be hidden. At first, Steganos for Windows hides characteristics of the file (title, attributes, etc.) and then its content, i.e. hidden line. Shown below program works with lines, i.e. it hides only hidden lines. Consequently, the size of the container in the first mode and for Program Steganos for Windows will be about 7-10 Kb. In the second mode, the size of the container should be much bigger as only one bit can be hidden in one line in this mode. So, to hide the same line it will require a container 8 times bigger, i.e. 50-80 Kb. Modern Web-sites in the Internet have a quite big size (50-150 Kb), which is enough to hide information in the second mode. So, this algorithm can be used for copyright protection and transmission of hidden information via open channels of the Internet. Below, in pictures 7 and 8 there are shown block-schemes of the algorithms of the first and second modes.

Picture 7. Block-scheme of the algorithm of the work of the program in Mode 1

Picture 8. Block-scheme of the algorithm of the work of the program in Mode 2

Description of the program The supplement is written in a programming language “Java”. The choice of the language is conditioned by the fact that its programs are crossplatformed. It means that supplements are not tied up to the particular operational system. They work so good in Windows as well as in UNIX systems, and, besides, in any other platform where virtual Java machine is fixed. This language is protected from the overfilled buffer, i.e. it is unlikely that during the work the supplement will hover or will lead to a mistake of memory. One of the peculiarities of this language is that it doesn’t have any basic unsigned type, i.e. such a variable quantity as byte (type which takes one byte in memory is mainly used in work with files) has maximum meaning 128 (0x80), left range (0x81-0xFF) is used for negative numbers. But it doesn’t influence on this program as it works in the 16th system, i.e. a symbol from the table of ASCII codes is used for every 16th meaning of the byte. The program has a simple and intuitively clear interface, it works in a dialog-mode, and so it shouldn’t cause any difficulties in usage. Interface of the program Changing modes is done from the menu by pushing “mode”: Default mode is Mode 2. Piloting the program is done through two windows. One is for hiding information and the other is for disclosing it.

Picture 10. window for piloting disclosing the data

To the right of these windows there is a panel(board) which shows the web-site where the program hides the information. Conclusions These articles dealt on the principles of hiding information in HTML-files. Two new algorithms for hiding information were suggested. Their characteristics were analyzed and main fields of their usage were defined. Список литературы. 1. Belyaev A., «Steganographic: hidden information», access mode: http://mimicria.narod.ru/HTML/Stego/Html/sou rces.html, free. 2. Kartashov D.V., Chijuhin G.N., «Text steganographic», access mode: http://www.pniei.penza.ru/conf/tom4/005/c1.ht m, free. 3. N. E. Gerasimov, I. V. Minin, O. V. Minin, STEALTHOGRAPHIC PROTECTION OF INTELLECTUAL PROPERTY IN WWW DOCUMENTS // Scientific symposium TECHNOMAT & INFOTEL 2007, BULGARIA 4. Tekin V., «Text steganographic», - World of PC, № 11, 2004.

Picture 9. Window for piloting hiding the data


				
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Description: My first work about Text steganographics in Web