Steganography. Стеганография

Almaty University of Power Engineering and Telecommunications

Chair of Foreign Languages

Semester work №1

Steganography

Made by:

students of РЕТ-16-4 group

Matsutsa E.E.

Rakhimova A.A.

Checked by:

Yerzhanova J.B

Almaty, 2019

Content

Introduction        3

1. Text………………………………………………………………………………….4

Steganography        4

Translation……………………………………………………………………………..6

2. Tasks………………………………………………………………………………..8

2.1 Dictionary        8

2.2 Questions        8

3. Lexical and grammatical exercises        9

3.1 Glossary        9

3.2 International words:        10

3.3 Determine the part of speech by suffix:        10

Annotation        11

List of references        13

Introduction

The relevance of a problem of information security constantly grows and stimulates search of new methods of information security. Modern computer technologies, progress in area of global computer networks and means of multimedia are provided by a possibility of development and realization of the new methods intended for ensuring computer information security. Computer technologies have given a new impulse to development and improvement of the new direction in the field of information security - a computer steganografiya.

Steganografiya – is a science about the hidden information transfer by preservation in secret of the fact of transfer. Historically this direction has appeared the first, but then has been in many respects forced out by cryptography. Unlike cryptography which hides contents of the confidential message the steganografiya hides his existence. Тайнопись it is carried out in the most various ways. Common feature of these ways is that the hidden message is built in some the harmless, not drawing attention object. Then this object is openly transported to the addressee. At cryptography existence of the encoded message in itself draws attention of opponents, at a steganografiya existence of the hidden communication remains imperceptible.

There are two main directions in a computer steganografiya: connected with digital processing of signals and not connected. In the latter case messages can be built in headings of files, headings of packages of data. This direction has limited application in connection with relative ease of opening and/or destruction of the hidden information. The majority of the current researches in the field of a steganografiya are anyway connected with digital processing of signals. It allows to say about a digital steganografiya.

Steganografiya is an effective program and technical method of concealment of data and protection them from unauthorized access. But nevertheless it is only one of ways of information security. Effective use of a steganografiya together with other methods of information security will ensure multilevel safety.

Steganography

When people think about Information Security the first word that generally comes mind is "Hacking", but there are many disciplines in security and one of them is called "Steganography", an offshoot of encryption and "data hiding".

The word "steganography" can be divided in two parts: stegano + graphy. "Stegano" comes from the Greek word "steganos" meaning "covered" and "graphy" which comes from the Greek word "graphein" meaning "writing:". Thus, steganography literally means "covered writing".

Steganography is an ancient art of covering messages in a secret way such that only the sender and receiver know the presence of the message. This allows one party to communicate with another party without the third party being aware that communication is occurring. Usually, the data is concealed inside an innocuous cover so that even if a third party discovers the cover, there are no suspicions about the data hiding inside the cover.

There is something really important about steganography: There must not be any easily perceived change in the file that is hiding the message.

Basic Steganographic Model. A basic steganographic model is shown in Figure 1. First we need to understand the three blocks in the left of the image:

Cover File, 'X': This is the file that we will use for hiding the information.

Message, 'M': This is the secret information that we want to hide into 'X'.

Stego-Key, 'K': Some steganographic methods need to use specific keys, or data, for hiding and recovering 'M' from 'X'.

Once we have this information, we can apply the steganographic method, 'f(X,M,K)'. The output after applying the method is called "Stego-File", denoted with 'Z'.

For recovering the message, we will apply the inverse process using the same Stego-Key used for hiding the message.

[pic 1]

Figure 1. Basic Steganographic Model

The Least Significant Bit (LSB) method is a really common and famous steganographic method in which the secret information is hidden in the least significant bits of the image.  There are 2 different LSB steganographic methods: LSB Replacement and LSB Matching.  In LSB Replacement, all we need to do is to change the least significant bit with one bit of the secret message which we want to hide. It is really easy to detect if this method has been used because the algorithm complexity is almost null. In LSB Matching, we will also modify the LSB with one of the bits of the secret message but it uses some probabilistic and tstatistic operations for spreading the hidden information across the entire the cover file without modifying all the bits that contain part of the secret message.

Characteristics of Steganographic Techniques

In steganography, the message to be hidden inside the cover–media must consider the following features.

Hiding Capacity: This feature deals with the size of information that can be hidden inside the cover file. A larger hiding capacity allows use of a small cover and thus reduces the band-width required to transmit the stego–media. For example, if we have an RGB image with a size of 200 x 200 pixels, that means that we have 120,000 color values to be used as cover values for the secret message (200:width x 200:height x 3:R,G,B), then if we use only one bit per color channel for hiding the message we have a hiding capacity of 120,000 bits or 15,000 bytes, if we use 2 bits per color channel for hiding the message we have 30,000 bytes, but if we use only one color channel and one bit per pixel, the hiding capacity will be 40000 bits or 5000 bytes.