Figure1 – The flowchart of jargon method
Автор: В.. Сидорчук, Н.Е. Губенко, Д.С. Сипаков
сточник: 9-я Международная студенческая научно-техническая конференция, Астрахань, 15–19 апреля 2019 года [Электронный ресурс] : материалы / Астрахан. гос. техн. ун-т. – Астрахань : зд-во АГТУ, 2019.
Steganography is often defined as the science and art of information concealment in a so-called container, the transferring of which from one person to another does not arouse suspicion. Unlike cryptography, whose aim is to protect the message itself, the main purpose of stenography is to protect the very fact that contains a hidden message.
Modern stenographic tools mainly work in information environments that have greater redundancy. If you take into account the information which contains large amounts of noise data (such as sounds or images), the written text contains a small amount of redundant information that can be used to hide certain data.
The methods of linguistic stenography are hidden implantation of coded arbitrary information into the texts, relying on linguistic resources. These methods have been known since medieval times. With the development of computer and information technologies, the medieval methods of linguistic stenography were revived at a new level and make it possible, in some cases, to hide the fact of secret correspondence not only from the “athematic censor”, which monitors telecommunications networks, but also from the human himself.
The first method is the jargon method. The use of jargon in the text may confuse unauthorized reader. While implementing this method, a database with inserted words and corresponding jargons which will replace the words is created.
This method is simple to implement, and while using it, there is no suspicion about the presence of hidden information in case of saving the text in a readable form. However, this method has drawbacks: the words database is limited to the list of words used by the participants in correspondence; the recipient must also know the used jargons; in case of unsuccessful use of jargon, the intruder can understand the hidden meaning of the message.
Figure1 – The flowchart of jargon method
The second method is semagramm. The semagramm is a way to hide information through signs or symbols. For example, placing objects on the table in a certain sequence, a certain sequence of numbers, etc. for an outsider won’t be seen.
Figure 2 – The flowchart of semagram method
Also, there are text semogramms. Text semogramms are messages hidden inside the text. To send any message, you can use capital letters, spaces between letters or words, features of underscore, etc.
Among the advantages of this method it is worth noting that its implementation is simple and invisible to unauthorized reader.
The disadvantage of this method is the fact that because of its simple implementation, an intruder can quite easily get the hidden information.
The third method is hidden coding. Hidden coding is considered a special case of linguistic steganography. It is also more difficult to implement, but it provides high data secrecy. This method uses a special function that encrypts and decrypts the message for transmission. The method uses a “container” in which the hidden message is placed (see Figure 3). After receiving the hidden message, it is retrieved from the “container” by special algorithm.
Figure3 – Classic flowchart of hidden coding method
This method has strong decryption resistance, but high implementation complexity.
The fourth method is open coding. It means the following: the hidden message is placed into the text so that it does not catch the eye of the outsider. When it is necessary to analyze, computers and people demonstrate different methods of recognition and perceiving stenographic messages. This method is simple to implement, but easy to give away hidden data.
The last method is phonetics. This method can be used if you know exactly which language the filter is programmed. This filter searches for words in that language which is mainly used by people in the country. Of course, it is impossible to say with certainty how exactly the filter is programmed. But to get closer to understanding, you can use phonetically similar words. This method is most suitable if you use an alphabet different from the one adopted in your country (for example, Latin instead of Cyrillic).
This method is simple to implement, but the information is not actually hidden and an intruder can easily get hidden information.
Thus, having examined each method, a comparison table which takes into account the following criteria for analyzing the methods: implementation complexity, decryption complexity, difficulty in determining the presence of a hidden message was compiled. Each method is scored from 1 to 3.
Table 1 –The comparison of stenography methods
During the research, various methods of linguistic steganography were analyzed, and a comparative table was constructed with the above methods. They were compared in terms of implementation complexity, decryption complexity, and difficulty in determining the presence of a message. After analyzing Table 1 it has been turned out that the method of hidden coding and the method of semagrams are the most effective in the implementation.
1. Большаков .А., А.Ф. Гельбух. Раздельное представление словосочетаний для существительных единствен-ного и множественного числа. // Труды Международного Семинара по вычислительной лингвистике и ее приложениям. Диалог’96. Пущино, 1996.– с. 42–44.
2. FrontLine International foundation for the protection of human rights defenders [Электронный ресурс] / L.Trappeniers [et al.] // Computer. – Электрон. дан. - 2013. - Vol.46, No 2. – P. 24-25. – Режим доступа: https://equalit.ie/esecman/russian/chapter2_7.html
3. Мельчук, . А. Опыт теории лингвистических моделей «Смысл U Текст». Семантика, синтаксис. М.: Наука. – 1974. – 314 с.
4. Стеганография [Электронный ресурс] //Академик, 2018: [сайт] – URL: https://dic.academic.ru/... – агл. с экрана.
5. Электронная библиотека студента [Электронный ресурс.] // Библиофонд, 2018: [сайт] – URL: https://www.bibliofond.ru/...